Intermolecular Forces

Intermolecular Forces are the attractive forces between 2 molecules. Intramolecular Forces are the bonding forces within a molecule. 

Intermolecular vs. Intramolecular Forces

Concept: Understanding the difference between intermolecular and intramolecular forces 

3m
Video Transcript

We are going to say when we are looking at any type of molecular substance, we have to realize that there were two types of forces at work.
So if we take a look at water, you are going to discover that there are two major forces. We’re going to say that the first major force is called intramolecular force. Intra means that the force operates within the molecule. So inside of water, the force is an intramolecular force. Intramolecular forces influence the chemical properties of water.
Remember, if we were drawing water, oxygen goes in the center. It has 6 valence electrons because it’s in group 6A. Hydrogens are on the outside because they never go in the center. They have only one valence electron because they are in group 1A and they only make one bond. So water would look like that. So let me draw it down here actually. So remember, we’d say that the forces operating inside the water are intramolecular forces.
Now, other than intramolecular forces, we have intermolecular forces. Now, intermolecular forces are the forces between different molecules. So here we have water and it can interact with the compound we are just going to say is B, compound B. Their interaction is an intermolecular force interaction. And we are going to say, intermolecular forces don’t influence the chemical properties of a compound, they influence the physical properties.
What do I mean by physical properties? I mean like boiling point, something called vapor pressure, freezing point, melting point. These are the kinds of properties that intermolecular forces interact and influence. We’ll see those later on but just realize the difference between intra and inter. intra is within; inter is between, between different compounds.
We are going to say that there are five major types of intermolecular forces that you should be aware of. And here we are going to go from the strongest intermolecular to the weakest intermolecular. 

Intermolecular forces influence the physical properties of compounds, whereas intramolecular forces influence the chemical properties of compounds. 

Concept: The First and Strongest Intermolecular Force

5m
Video Transcript

First intermolecular force is the force that exists between an ion and a polar compound, so this is called ion-dipole. Now, an example of ion-dipole is we could have NaCl, remember this is sodium chloride, it’s ionic, and we throw it into water. Now, ionic compounds are polar compounds. And they’re highly polar because, remember, we’ve talked about this before, we say if your difference in electronegativity is 0.4 or greater, you are going to be polar. If it’s greater than 1.7 and higher, you’re going to be ionic. So the difference in their electronegative numbers is very high, so it’s going to be a polar type of compound. All ionic compounds are polar.
And we’re going to learn that water, which is called the universal solvent, it’s called universal because it’s highly polar, so it dissolves a lot of polar things. So polar ionic compound, polar solvent, which is water, polar and polar will interact. So the polar water is going to split this up into its ions. Na is group 1A so it’s going to be Na+ aqueous plus Cl- aqueous . Remember Cl is in group 7A, so it’s -1. Now, what does aqueous mean? All aqueous means is that the water is actually wrapping itself around the ions. This is the ion-dipole interaction.
Now if we wanted to see what it looks like, let’s say we took the sodium ion, now aqueous again means that the water is surrounding it, but which parts of the water are surrounding it? We should realize that oxygen is very electronegative. This compound here is polar if we follow the rules. Because it’s polar, we are going to say that one end is partially positive; the other end is partially negative. Oxygen has a larger electron negative number so this end will be partially negative. The hydrogens are less electronegative, so they are going to be partially positive.
Sodium is positively charged, and remember which side of the water is going to be attracted with it? Opposites attract. So the negative portion of the water will be attracted to it, the partially negative portions. It’s not going to be one molecule surrounding the ion, it’s going to be multiple water molecules surrounding it because we are in solution, it’s in a bucket of water. There’s hundreds and hundreds of water molecules all around, so they all try to surround the ion.
So it’s the interaction between the ion, the positive ion, and the partially negative end of the water molecule. This little dash green line means that it’s not a full bond, it’s just an interaction. They are communicating with each other; they’re partially attracted to each other.
Intermolecular forces are not bonding forces. Remember, we are going to say that intramolecular forces are bonding forces; intermolecular forces are not bonding forces. They are not bonding; they are just attracted to one another. So these little green lines are just an attraction for the positive ion to the partially negative oxygen.
And if we drew chlorine, we’d show that the partially positive ends, the hydrogens, will be attracted to the negative chlorine. That will be our ion-dipole interaction.
So here is an example of ion-dipole and we are going to say basically, fundamentally, we have ion-dipole anytime we have an ionic compound dissolving in a polar liquid, like water. Water is polar based on the rules that we learned.

This intermolecular force deals with the attraction between an ion and a polar compound

Concept: The Second Intermolecular Force

3m
Video Transcript

Now, the next one is easier for us to grasp. This next force is the force that exists anytime H is connected to F, O, N. not fun exactly but F, O, N - fluorine, oxygen, nitrogen. So anytime H is connected to those 3 elements, it’s going to be hydrogen bonding.
So what are some examples of hydrogen bonding? Well, let’s think of some. Water is an example of hydrogen bonding because H is connected directly to oxygen. HF, H is directly connected to fluorine. NH3, H is connected directly to nitrogen. So these three examples would also be hydrogen bonding. And, again, hydrogen bonding is not a real bond; it’s just an interaction.
So a good example is we could have water forming an interaction with another water if we wanted, or even NH3. That dotted red line is not a real bond it’s just an attraction that the molecules have for one another. That would be hydrogen bonding.
Now hydrogen bonding is an extremely important force because water has hydrogen bonding. Water has a very high heat capacity, specific heat capacity. That means that it takes a lot of energy to break water into its molecules. And the reason it takes so much energy to break it up is because water has hydrogen bonding. Hydrogen bonding makes the molecules stronger because all of these attractive forces after first to be broken up before we can start to boil water.
So if you ever wanted why water takes so much time to boil? It’s because of these intermolecular forces. All the water molecules are partially connected to each other, partially attracted to each other. So as a result, it’s going to take a lot of energy to break those partial attractions first before we can begin to vaporize the water.

This intermolecular forces exists anytime hydrogen is directly connected to fluorine, oxygen or nitrogen

Concept: The Third Intermolecular Force

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Video Transcript

Now, the force exists when we have two polar covalent compounds attracted to one another. We are going to say here that this is called dipole-dipole. Now, the word dipole means polar, so dipole-dipole means polar-polar. So the name is kind of telling us the reaction. It’s telling us we have a polar A attracted to a polar B. So dipole means polar, so dipole-dipole, again, means polar-polar.
So if we think about it, we can just think of a polar compound, maybe one that we drew earlier. One that we drew earlier would be SiBr4 2-, we know this compound was polar when we drew it. And let say it’s attracted to itself or maybe even attracted to something else that’s polar, PH3. So their attraction to one another, because they are both polar, will be dipole-dipole.

Concept: The Fourth Intermolecular Force

2m
Video Transcript

The fourth intermolecular force exists anytime we have a nonpolar covalent compound having a partial interaction with a polar covalent compound. Now this is called dipole/induced-dipole. Now, we said that the word dipole means polar. Now, the word induced-dipole means nonpolar. So dipole/induced-dipole means polar interacting with non-polar. That’s all that means.
So a good example here, something’s that polar and nonpolar interacting, we could have let’s say, water, which we know is polar, interacting with CCl4. Carbon is in the center there. It’s surrounded by the same chlorines all the way around, so it’s a nonpolar compound. It has no lone pairs, so we are using row 1 to determine if it’s polar or nonpolar. Based on the rules for row 1, this compound will be nonpolar. So this compound is nonpolar; this compound is polar. And the interaction that they have with one another is dipole/induced-dipole. 

This intermolecular force deals with the attraction between a polar and nonpolar covalent compound

Concept: The Fifth Intermolecular Force

6m
Video Transcript

We’re going to need some room to do this last one, so I’m going to remove myself from the image, guys, so we have more room to work with. So actually, I’m coming back. So actually I’m going to stand in the image guys so that we can work on this.
So the last force is the force that exists when two nonpolar covalent compounds are interacting. So we have two non-polars. Now, this last force goes by a ton of different names. One name that we usually give to it is called London-dispersion forces, that’s one name that it can have. Another name for it is van der Waals force. And then a third name that it could have is induced dipole-induced dipole.
So just remember, this last force can be called any one of these three. The main name is London-dispersion but it can also be called one of the other two. We are going to say that this force exists anytime we have nonpolar compounds. So we could have CCl4 interacting with CH4.
And there’s a few things we need to know about his last force. One, that this force is the weakest force. Also, we need to realize that every compound, no matter what it is, has this force. This is a force that’s present in all compounds.
So water, water's main intermolecular force, strong intermolecular force, would be hydrogen bonding but it also has London-dispersion. Because London-dispersion is weaker, when we scan water we will see that the vast majority of its force comes from H-bonding and a very, very small percentage of its force comes from London-dispersion. So again remember, all compounds fundamentally have London-dispersion forces.
And what we should realize here when it comes to London-dispersion forces, we are going to say that compounds with London-dispersion as their only force, we are going to say that the more they weigh, the greater their London-dispersion will be. So these two compounds are both nonpolar, so they both, fundamentally, have London-dispersion as their only force.
CCl4 London-dispersion will be greater than CH4 because CCl4 weighs more. The more you weigh, the greater your London- dispersion. We are going to say the more you weigh, the more polarizable you are.
Because when it comes to London- dispersion, the way it works is, let’s say that this blob here represents a compound and its main force is London-dispersion. Now how can two things have an interaction to each other if they are both nonpolar? The way it works is polarizability.
What’s going to happen is electrons are going to spontaneously align themselves on one end of the compound. So electrons, for a split second, will move to the left side. They just randomly do that. They are all going to move at the left side. So if all the electrons move to the left side, this side is going to become negative, partially negative. If all the electrons are leaving the right side, this side going to become partially positive.
Then what happens here is polarizability. So the compound that’s nonpolar, usually, for a split second, can become polar. It then comes near a compound that’s strictly nonpolar. So CCl4 comes near CH4. Because this guy here becomes polar for an instant. It’s going to make this compound become polar for an instant as well. This partially positive end here is going to attract electrons. So it’s going to cause the electrons to shift in compound B to this side so they’re close to the partially positive charge. Then moving to the left will cause this side over here to become partially positive.
Now this happens for only an instant. And then the molecule returns back to being nonpolar. But that instant that this happens, that’s when we get this interaction between nonpolar compounds. It happens for just a moment, but in that moment, that’s where we have the London-dispersion happening. And remember, all compounds have London-dispersion. Compounds that are nonpolar have it as their main and only force.
So remember these are your major types of intermolecular forces that your professor will expect you to know, and a majority of them comes from fundamentally knowing how to draw.
Ion-dipole, you don’t really need to know how to draw because ion-dipole exists anytime we have an ionic compound. So if we have an ionic compound and its dissolving in a polar solvent, like water, it’s going to be ion-dipole. H-bonding, we kind of don’t need to really know how to draw either because if H is connected to F, O or N, it’s automatically H-bonding.
It’s when we get to dipole-dipole and London-dispersion where it’s important we know how to draw because you have to learn how to draw this compounds to be able to determine, is it a polar covalent compound or is it a nonpolar covalent. That is where it becomes essential to know what kind of structure we have and go over the rules for polarity. 

This intermolecular force is found in all compounds, but it's the main intermolecular force of nonpolar covalent compounds

Example: Based on the given compounds, answer each of the following questions:

CH3CH3,       KBr,        C6H5OH,           CaS,             Ne

a. Which compound will have the lowest boiling point?

 

b. Which compound will have the highest surface tension.

 

c. Which compound will have the highest vapor pressure. 

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Problem: The predominant intermolecular force in C6H5NH2 is:

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Problem: The predominant intermolecular force in HBr is:

3m

Problem: The predominant intermolecular force in ZnBr2 with H2O is:

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Problem: The predominant intermolecular force in Ne with H2O is:

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Solubility & Intermolecular Forces

Solubility deals with the dissolving of a solute in a solvent in order to create a solution

Concept: Understanding the Theory of "Likes" dissolve "Likes"

3m
Video Transcript

Why was it so important that we identify a compound as polar or nonpolar? Because we're going to say that compounds with the same intermolecular force, or polarity, will dissolve into each other to form a solution. Now we're going to say that if you have a polar and a polar, they're going to mix together well. If you have a non-polar and a polar, their polarities are different, so they won't be able to dissolve into each other to form a solution.
We're going to say according to the theory of likes dissolve likes, basically, the two compounds have to have the same intermolecular force. If they have the same intermolecular force, they have the same polarity. But they could also have different intermolecular forces.
Let's say one compound had hydrogen bonding and the other one had dipole-dipole, that's okay because hydrogen bonding and dipole-dipole are both polar forces. Because they're both still polar, they'll be able to dissolve with one another. But let's say one had dipole-dipole and the other one had London-dispersion. Dipole-dipole is polar. London-dispersion is non-polar. Because of their differences in polarity, they will not mix.
Also, we're going to say that there's a difference between a mixture and a solution. We're going to say mixtures, we've talked about this so many weeks ago, mixtures come in two types. We have homogeneous or heterogeneous. We're going to say homogeneous mixtures mix together. They dissolve into each other. We're going to say that heterogeneous mixtures do not mix.
Oil and water is a good example that we've talked about. They won't mix because why? Oils are non-polar solvents. They're non-polar. Water, on the other hand, is polar. As a result, polar and non-polar do not mix. That's why oil and water don't mix together at all. Mixtures come in these two types.
A solution, all solutions, are just homogeneous mixtures. Remember the difference. Mixtures come in two types. They can either be homogeneous, where they mix together, or heterogeneous, where they don't. All solutions are just homogeneous mixtures. In a solution, we can dissolve both things into each other, so they do mix.

In order for a solvent to dissolve a solute both components have similar polarities. 

Example: Identify the intermolecular forces present in both the solute and the solvent, and predict whether a solution will form between the two. 

CCl4 and P4

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Example: Identify the intermolecular forces present in both the solute and the solvent, and predict whether a solution will form between the two. 

CH3OH and C6H6

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Example: Identify the intermolecular forces present in both the solute and the solvent, and predict whether a solution will form between the two. 

C6H5CH2NH2 and HF

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Example: Identify the intermolecular forces present in both the solute and the solvent, and predict whether a solution will form between the two. 

IF4­ -   and NH3

5m

Problem: Which of the following statements is/are true?

a) Methane will dissolve completely in acetone, CH3COCH3.

b) Hydrofluoric acid (HF) will form a heterogeneous mixture with tetrachloride, CCl4.

c) Pentane will form a homogeneous mixture with CBr4.

d) Methanethiol (CH3SH) is miscible in fluoromethane (CH3F).

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Intermolecular Forces Additional Practice Problems

Select the molecule with the strongest dispersion force with itself.

a. N2

b. O2

c. Br2

d. F

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The strongest interaction between C3H8 and CH3OH is

a. dispersion forces 

b. dipole-dipole forces

c. dipole-induced dipole forces

d. hydrogen bonds 

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Select the single best answer. 

What is the strongest interparticle force in a sample of SO 2

(A) ionic bonding forces 

(B) dipole-dipole forces 

(C) dispersion forces 

(D) ion-induced dipole forces 

(E) dipole-induced dipole forces 

(F) hydrogen bonding forces 

(G) ion-dipole forces

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For each pair below, which of the two has the higher boiling point and state your reason why? 

(a) helium or argon? 

(b) ethanol or acetone?

(c) pentane or heptane?

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What intermolecular force(s) is/are present in solid SO 3 ?
1. London dispersion
2. dipole-dipole
3. hydrogen bonding

a. 1 only

b. 2 only

c. 3 only

d. 1 and 2

e. 1 and 3 

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Which of the following substances has the highest boiling point?

He I2 O2 H O2 He I2 H

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What type of interaction occurs between atoms in a nonbonding atomic solid.

a. covalent bonding

b. weak dispersion forces

c. polar bonding

d. ionic bonding  

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Rank the four compounds shown below in order of increasing boiling point.

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Which of the following molecules can hydrogen bond? 

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Which molecule or molecules can form hydrogen bonds with water? Select all that apply.

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What is the strongest type of intermolecular force between solute and solvent in each solution?

(a) CsCl(s) in H2O(l)

(c) CH3OH (l) in CC14(l)

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What is the relationship between solvation and hydration?

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Gluconic acid is a derivative of glucose used in cleaners and in the dairy and brewing industries. Caproic acid is a carboxylic acid used in the flavoring industry. Although both are six-carbon acids (see structures below), gluconic acid is soluble in water and nearly insoluble in hexane, whereas caproic acid has the opposite solubility behavior. Explain.

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Which member of each pair is more soluble in water? Why?

(a) CH3CH2OCH2CH3(l) or CH3CH2OCH3(g)

(b) CH2Cl2(l) or CC14(l)

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Which member of each pair is more soluble in diethyl ether? Why?

(a) NaCl(s) or HCI(g)

(c) MgBr2(s) or CH3CH2MgBr(s)

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What is the strongest type of intermolecular force between solute and solvent in each solution?

(a) C6H14(l) in C8H18(l)

(b) H2C=O(g) in CH3OH(l)

(c) Br2(l) in CC14(l)

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What is the strongest type of intermolecular force between solute and solvent in each solution?

(a) CH3OCH3(g) in H2O(l)

(b) Ne(g) in H2O(l)

(c)N2(g) in C4Hl0(g)

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What is the strongest type of intermolecular force between solute and solvent in each solution?

(a) Cu(s) in Ag(s)

(b) CH3Cl(g) in CH3OCH3(g)

(c) CH3CH3(g) in CH3CH2CH2NH2(l)

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Which gives the more concentrated solution, stearic acid [CH3(CH2)16COOH] in (a) H2O or (b) CCl4? Explain.

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Which gives the more concentrated solution, (a) KNO3 in H2O or (b) KNO3 in carbon tetrachloride (CCl4)? Explain.

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Acetic acid is miscible with water. Would you expect carboxylic acids with general formula CH3(CH2)nCOOH to become more or less water soluble as n increases? Explain.

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What types of intermolecular forces give rise to hydration shells in an aqueous solution of sodium chloride?

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What is the strongest interparticle force in each substance?

a. CH3OH

b. CCl4

c. Cl2

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Polar molecules exhibit dipole-dipole forces. Do they also exhibit dispersion forces? Explain.

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Intermolecular forces are depicted in the scenes below:

 

(a) Name the type of force being depicted in each scene.

(b) Rank the forces in order of increasing strength.

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Oxygen and selenium are members of Group 6A(16). Water forms H bonds, but H2Se does not. Explain.

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Why are covalent bonds typically much stronger than intermolecular forces?

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Three solids are represented below. What is the predominant type of intramolecular bonding in each?

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Which of the following will be the most soluble in water?

a. CH3CH2CH2CH2CH2CH2OH 
b. CH3CH2CH2OH
c. CH3CH2CH2CH2OH
d.  CH3CH2CH2CH2CH2OH

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Water and toluene are not miscible. Which of the following is most likely the formula of toluene?

a. C6H5CH3
b. C6H12O6
c. CH3OH
d. CH3COOH

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Consider the formation of the three solutions shown in the table.

a. Rank the solutions A, B, and C from the most exothermic to the most endothermic.
b. Rank the enthalpy of solution from most exothermic to most endothermic. To rank items as equivalent, overlap them.
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Spontaneous dissolving under standard-state conditions at 25oC occurs with a mix of

a. CH2Cl2 & H2O
b. KNO3 & CH2Cl2
c. acetone & H2O
d. CH2Cl2 & NaCl

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Spontaneous dissolving under standard-state conditions at 25oC occurs with a mix of:

a. KNO3 & n-butanol
b. I2 & CH2Cl2
c. CaCO3 & hexane
d. acetone & KNO3
 

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Choose the molecule or compound that exhibits dipole-dipole forces as its strongest intermolecular force.

a. NH3

b. CF4

c. SO2

d. BCl3

e. H2

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Ammonia's unusually high melting point is the result of

a. dipole-dipole forces.

b. London dispersion forces.

c. hydrogen bonding.

d. covalent bonding.

e. ionic bonding.

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What is the strongest type of intermolecular force present in CHF 3?

a. dispersion

b. dipole-dipole

c. hydrogen bonding

d. ion-dipole

e. none of the above

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What is the strongest type of intermolecular force present in NH 2CH3?

a. dispersion

b. dipole-dipole

c. hydrogen bonding

d. ion-dipole

e. none of the above

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Choose the molecule that exhibits London (dispersion) forces as its strongest intermolecular force.

a. Cl2

b. CO

c. HF

d. NaCl

e. All of these have intermolecular forces stronger than dispersion

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Choose the molecule that exhibits dipole-dipole forces as its strongest intermolecular force.

a. H2

b. SO2

c. NH3

d. CF4

e. BCl3

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What intermolecular forces are present in each of the substances?

a. CH4

b. C3H8

c. CH3F

d. HF

e. C6H5OH 

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In the molecule below, how many atoms could make hydrogen bonds with water?

a. 5

b. 7

c. 9

d. 10

e. 12

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Which type(s) of bonding is (are) found within hydrocarbon molecules?

a. Hydrogen Bonding

b. Covalent Bonding

c. Van der Waals

d. Metallic

e. Ionic

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Rank the following molecules in order from most soluble in water to least soluble in water.

methane: CH4, hexanol: C6H13OH, table salt: NaCl, propane:C3H8
 

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What is the strongest type of intermolecular force between solute and solvent in the following solution?

CH3OCH3(g) in H2O(l)

a) ion-dipole

b) H bond

c) dipole-dipole

d) ion-induced dipole

e) dipole-induced dipole

f) dispersion

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What is the strongest intermolecular force in SO 2?

a) dipole-dipole

b) london dispersion

c) ionic

d) hydrogen bonding

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Determine the kinds of intermolecular forces that are present in the follwoing element or compound: SiH4

a) Dispersion forces

b) Dipole-dipole forces

c) Hydrogen bonding

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Determine the kinds of intermolecular forces that is/are present in Kr.

a) dispersion forces

b) dipole-dopole forces  

c) hydrogen bonding  

d) dispersion forces & dipole-dipole forces

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Determine the kinds of intermolecular forces (from below) that are present in the compound H2S.

a) dispersion forces

b) dipole–dipole forces

c) dispersion forces and dipole–dipole forces

d) hydrogen bonding

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Rank the following types of intermolecular forces in general order of decreasing strength (strongest to weakest).

London dispersion, ion-dipole, hydrogen bonding, dipole-dipole

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Classify each property as associated with a liquid that has strong or weak intermolecular forces.

high viscosity, low boiling point, low viscosity, high boiling point, high surface tension, low surface tension, low vapor pressure, high vapor pressure

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Identify which of the following are correct conditions for forming a hydrogen bond:

a) A hydrogen bond is equivalent to a covalent bond.

b) The CH4 molecule exhibits hydrogen bonding.

c) A hydrogen bond is possible with only certain hydrogen-containing compounds.

d) Hydrogen bonding occurs when a hydrogen atom is covalently bonded to an N, O or F atom.

e) A hydrogen atom acquires a partial positive charge when it is covalently bonded to an F atom.

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Identify which of the following molecules can exhibit hydrogen bonding as a pure liquid.

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Rank these compounds by their expected solubility in hexane C6H14.

C2H5OH, H2O, C2H6

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Rank these compounds by their expected solubility in hexane, C6H14.

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Identify the predominant type of intermolecular force in each of the following compounds. Drag each item to the appropriate bin.

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Which interactions and processes contribute to the dissolution of ionic compounds in water? Check all that apply.

A) Hydration
B) Affinity of oxygen towards cations
C) Ion–dipole interactions
D) Hydrogen bonding
E) Affinity of hydrogen towards anions
F) Dipole–dipole interactions

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For each solute, identify the better solvent: water or carbon tetrachloride. 

KF, NH3, C6H14, I2

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For each solute, identify the better solvent: water or carbon tetrachloride.

C6H6, I2, Na2S, CH3OH

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Identify the intermolecular forces present in each of these substances.

HF, CO, H2, and HCl.

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Identify the intermolecular forces present in each of these substances.

NH3, CO, CO2, CH3Cl

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Identify the intermolecular forces present in each of these substances:

HCl, He, CO, HF

Match these to the correct groups below.

1. Hydrogen bonding, dipole-dipole and dispersion
2. Dipole-dipole and dispersion only
3. Dispersion only

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List all the intermolecular forces present in pure acetone.

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Which of the following intermolecular forces of attraction is the strongest?

a. hydrogen bonding

b. dipole-dipole forces

c. dispersion forces

d. London forces

e. dipole-induced dipole forces

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What happens to these physical properties as the strength of intermolecular forces increases?

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Rank these compounds by their expected solubility in Hexane C 6H14. Rank from most soluble to lease soluble.

i) C3H8

ii) CH3OH

iii) H2O

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Identify which of the following molecules can exhibit hydrogen bonding as a pure liquid.

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For each solute, identify the better solvent: water or carbon tetrachloride.
C6H6, I2, Na2S, CH3OH

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Which of the following substances have polar interactions (dipole-dipole forces) between molecules? F2, Cl2, ClF, NF3

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Identify the intermolecular forces present in each of these substances.

NH3

CO

CO2

CH3Cl

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Which of the following molecules can form intermolecular hydrogen bonds as a pure liquid?

a. I, II, and III

b. II and IV

c. I and III

d. All molecules form hydrogen bond interactions

e. None of the molecules form hydrogen bond interactions

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Which compound below is likely the most soluble in water?

A. CH3CH2CH2CH2OH

B. CH3CH2CH2CH2F

C. CH3CH2CH2CH2Cl

D. CH3CH2CH2CH2CH3

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Which of the following can form intermolecular hydrogen bonds in the pure liquid?

A. 1 only

B. 2 only

C. 3 only

D. 2 and 3 only

E. 1 and 2 only

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For each solute listed below, identify the better solvent for solution formation: water or carbon tetrachloride

How many of these solutes will be miscible with water?

a. 2

b. 3

c. 4

d. 5

e. 6

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Which one of the following is most soluble in hexane (C 6H14)?

A. CH3OH

B. CH3CH2CH2OH

C. CH3CH2OH

D. CH3CH2CH2CH2OH

E. CH3CH2CH2CH2CH2OH

Watch Solution

Acetic acid (CH3COOH) forms a molecular solid. What type of forces hold it in a solid configuration?

I) London forces
II) dipole-dipole
III) hydrogen bonding

A. II only

B. I, II, and III

C. II and III only

D. I only

E. I and II only

F. II only

Watch Solution

Identify the dominant intermolecular force in the following species, respectively: RbCl, C6H6 (benzene), HI, Fe2O3, CH2NH.

a) ionic forces
b) hydrogen bonding
c) dipole-dipole
d) instantaneous dipoles

A. c, b, d, c, c

B. a, c, c, d, c

C. a, b, c, b, a

D. a, d, c, a, b

E. a, b, d, a, c

F. b, d, c, d, d

G. c, d, a, a, b

Watch Solution

Which figure best describes the hydrogen bonding between two water molecules?

Watch Solution

Methane (CH4) forms a molecular solid. What type of forces hold it in a solid configuration?

I) London forces
II) dipole-dipole forces
III) hydrogen bonding

1. I only

2. II only

3. I, II, and III

4. I and II only

5. II and III only

6. III only

Watch Solution

In which of these compounds would you find ONLY dispersion forces existing between the molecules?

I. CCl4;

II. NH3;

III. CO2;

IV. HBr.

1. II and III only
2. I and III only 
3. III and IV only
4. I and IV only
5. II only
6. III only
7. IV only
8. I and II only
9. II and IV only
10. I only

Watch Solution

Fill in the blank for the questions given below. 

 

Boiling Point increases with __________ intermolecular forces.

 

Vapor pressure __________ with weaker intermolecular forces.

 

For an exothermic reaction the higher the temperature the ________ molecules are dissolved in water. 

 

Watch Solution

 Define hydrogen bonding and indicate the hydrogen bonding interactions in water. 

Watch Solution

Predict what will happen when pure dimethyl ether (CH3OCH3) as a solute is mixed with pure methylamine (CH3NH2) as a solvent
i. the solute will dissolve in the solvent and a solution will form
ii. a solution will not form and two compounds will form separate layers.

because of the following reasoning.
iii. both solute and solvent only have London dispersion forces so these will be the strongest intermolecular forces in solution.
iv. Since both solute and solvent do not form hydrogen bonds, dipole dipole interaction will be the strongest intermolecular forces promoting solution formation.
v. both solute and solvent from hydrogen bonds so they will also form hydrogen bonds in solution.
vi. Since, only the solvent from hydrogen bonds, there will be no hydrogen bonds formed in solution and dipole dipole interaction will be the strongest intermolecular force promoting solution formation.
vii. Even though only the solvent forms hydrogen bonds there will still be hydrogen bonds formed in solution between the solute and the solvent.

A. ii and iii

B. i and iv

C. i and v

D. i and vi

E. i and vii

Watch Solution

Which of the following statements is/are correct?

i. Heptane (CH3CH2CH2CH2CH2CH2CH3) is soluble in water.
ii. Methylene fluoride (CH2F2 is soluble in butane (CH3CH2CH2CH3)
iii. Ammonia is soluble in n-propanol (CH3CH2CH2OH)

A. ii only

B. iii only

C. i and ii

D) ii and iii

E. i and iii

Watch Solution

What intermolecular attractive force is primarily responsible for the solubility of chlorine, Cl2, in water?

a. dipole - dipole
b. hydrogen bonding
c. dipole-induced dipole
d. ion-dipole
e. ion-induced dipole

Watch Solution

Which option contains substances that can exhibit only London dispersion forces, and no other intermolecular forces?

A) SF6        CH 4         Ne

B) H2O       CH 4         Ne

C) SF6        CH 4         NaCl

D) NaCl       H2O        CH 4

E) BaSO4    Ne          CH 4

Watch Solution

Give the major intermolecular force in seawater.

A) dipole-dipole

B) dispersion (London dispersion)

C) hydrogen bonding

D) ion-ion

E) ion-dipole

Watch Solution

Why is water an extraordinary substance?

A) Water has a low molar mass, yet it is a liquid at room temperature.

B) Water is the main solvent within living organisms.

C) Water has an exceptionally high specific heat capacity.

D) Water has strong hydrogen bonding.

E) All of the above.

Watch Solution

Identify the kinds of intermolecular forces that might arise between molecules of CH3OH.

1. None of these

2. dispersion forces, dipole-dipole

3. dipole-dipole

4. dispersion forces

5. hydrogen bonding

6. dispersion forces, dipole-dipole, hydrogen bonding

Watch Solution

True or false: Xe is more polarizable than Ne. _________

Watch Solution

At room temperature, nitrogen (N 2) and oxygen (O2) are both gases, but both will condense if the temperature is lowered enough. N2 condenses at 77K, and O2 condenses at 90K. Which of these molecules experiences weaker intermolecular forces? ___________

Watch Solution

For each of the following compounds, identify the strongest intermolecular force. In each of the compounds, carbon is the central atom.

CH4      __________________

CH3F    __________________

CH3OH __________________

 

Which compound would you expect to have the highest...

a. boiling point?                       ______________

b. molar heat of vaporization? ______________

c. viscosity?                             ______________

d. vapor pressure?                   ______________   

Watch Solution

Dispersion (London) forces result from

1. distortion of the electron cloud of an atom or molecule by the presence of nearby atoms or molecules.

2. the formation of a loose covalent linkage between a hydrogen atom connected to a very electronegative atom in one molecule and another very electronegative atom in a neighboring molecule.

3. the balance of attractive and repulsive forces between two polar molecules.

4. attraction between molecules in a liquid and molecules or atoms in a solid surface with which the liquid is in contact.

5. attractive forces between a molecule at the surface of a liquid and those beneath it which are not balanced by corresponding forces from above.

Watch Solution

The dominant forces between molecules (intermolecular forces) are ____ in origin.

1. electrostatic

2. electrodynamic

3. electromagnetic

4. gravitational

5. magnetic

Watch Solution

What is the strongest evidence for hydrogen bonding?

1. The boiling points of NH3, H2O, and HF are abnormally high compared with the rest of the hydrides in their respective periods.

2. Hydrogen is able to accept or donate electrons, so it is the most versatile atom in the periodic chart.

3. Hydrogen has an extremely low electronegativity.

4. Hydrogen can be considered either a metal or nonmetal.

Watch Solution

What types of intermolecular interactions does ammonia (NH 3) exhibit?

I) dispersion forces
II) dipole-dipole interaction
III) hydrogen bonding
IV) covalent bonding

1. I and II only

2. I, II, and III only

3. II and III only

4. II and IV only

5. I only

6. II only

Watch Solution

Which of the following can be expected to exhibit the strongest hydrogen bonding in the liquid state?

1. CH4

2. CH3COCH3

3. CH3OCH3

4. CH3OH

5. CH3CH3

Watch Solution

INTERMOLECULAR FORCES

Intermolecular forces (nonbonding forces) exist between molecules and influence the physical properties of the substance. The 5 most common intermolecular forces are:

1)  Ion-Dipole is the intermolecular force that exists between an ion and a polar compound. (Strongest)

Ex:   NaCl dissolved in H2O

 

2)  Hydrogen Bonding is the intermolecular force that exists when hydrogen is directly connected F, O, N. (2nd Strongest)

Ex:   NH3                                  H2O                  HF

 

3)  Dipole-Dipole is the intermolecular force that exists with polar covalent compounds. (3rd Strongest)

Ex: CHCl3               HCl                   HBr                  HI

 

4) Dipole/Induced-Dipole is the intermolecular force that exists when a nonpolar covalent compound interacts with a polar covalent compound. (4th Strongest)

Ex:       S8 (nonpolar solute) in  H2O (polar solvent)

 

 

5)  London Dispersion or Van der Waals Forces is the intermolecular force that exists with nonpolar covalent compounds. (Weakest)

 

 

Watch Solution

Determine the strongest intermolecular force present in each element of compound. 

a. HCl

b. Br2

c. PH3

d. NH

Watch Solution

Compared to CH4, NH3 has:

A.  stronger intermolecular forces, higher vapor pressure and higher boiling point.

B.  weaker intermolecular forces, higher vapor pressure and higher boiling point.

C.  stronger intermolecular forces, lower vapor pressure and lower boiling point.

D.  weaker intermolecular forces, lower vapor pressure and higher boiling point.

E.  stronger intermolecular forces, lower vapor pressure and higher boiling point.

Watch Solution

Which of the following molecules will show only intermolecular dispersion force?

Watch Solution

Soap has an ionic and a polar end. It works well to remove oil by

A) surrounding the oil with the nonpolar end, and the water interacts with the polar end.

B) surrounding the oil with the polar end, and the water interacts with the nonpolar end.

C) surrounding the oil and water with the nonpolar end.

D) surrounding the oil and water with the polar end.

Watch Solution

Which is expected to have the largest dispersion forces? 

A) C3H8

B) C12H26

C) F2

D) BeCl2

Watch Solution

What types of intermolecular forces exist between HI and H 2S?

A) dispersion forces and dipole-dipole

B) dipole-dipole and ion-dipole 

C) dispersion forces, dipole-dipole, and ion-dipole 

D) dispersion forces, hydrogen bonding, dipole-dipole, and ion-dipole 

E) dispersion forces, dipole-dipole, and ion-dipole

Watch Solution

Which one of the following substances will have hydrogen bonding as one of its intermolecular forces?

Watch Solution

List the following compounds in order of increasing strength of intermolecular forces.
Cl2         F 2          NH2CH2CH3

A. NH2CH2CH3 < Cl2 < F2

B. F2 < NH2CH2CH3 < Cl2

C. NH2CH2CH3 < F2 < Cl2

D. F2 < Cl2 < NH2CH2CH3

E. Cl2 < F2 < NH2CH2CH3

Watch Solution

Select the major force between the molecules in pure, liquid acetone.

A. ion-ion

B. ion-dipole

C. hydrogen bonding

D. dipole-dipole

E. dispersion

 

Watch Solution

What is the intermolecular force that exists between a calcium ion and water?

a. ion-dipole

b. Covalent bonding

c. London dispersion forces

d. ion-ion

e. dipole-dipole forces

Watch Solution

Give the major force between ethanol and water

A. dipole–dipole

B. dispersion

C. hydrogen–bonding

D. ion–dipole

E. ion–ion

Watch Solution

The predominant intermolecular force in BF3 is: 

  1. London Dispersion
  2. Hydrogen Bonding
  3. Ion-Dipole
  4. Dipole-Dipole
  5. Dipole-induced Dipole
Watch Solution

Rank the following solute‐solvent interactions in order of INCREASING strength of attraction.

I. K+ in H2O

II. CH3CH2NH2 in H2O

III. CO2 in CCl4

 

a) I < II < III

b) III < II < I

c) II < III < I

d) I < III < II

e) III < I < II

Watch Solution

Which of the following compounds exhibits hydrogen bonding?

A) CH3CH2NH2

B) C6H5OC6H5

C) CH3I

D) H2S

Watch Solution

Which of the following characteristics indicates the presence of  weak  intermolecular forces in a liquid?

a) a high critical temperature 

b) a low heat of vaporization

c) a high boiling point

d) a low vapor pressure

e) None of the above

Watch Solution

Intermolecular forces are:

            A.  between molecules and weaker than a chemical bond.

            B.  between two atoms within a molecule and weaker than a chemical bond.

            C.  between molecules and stronger than a chemical bond.

            D. between two atoms within a molecule and stronger than a chemical bond.

            E. between electrons within an atom and stronger than a chemical bond.

Watch Solution

Identify the principal intermolecular forces that exist between molecules in each of the following species:

a. C6H6

 

b. CH3Cl

 

d. CS2

 

e. CH3OH

 

f.  PF3

 

 

Watch Solution

For each of the following pairs of molecules, identify the dominate intermolecular force, and answer the associated question.

a. NH2CH2CH2CH3            N(CH 3)3

____________________   ____________________

Which of the above compounds is expected to have the highest viscosity?

 

b. CsF                                 ClF

____________________   ____________________

Which of the above compounds is expected to have the highest vapor pressure?

 

c. CO2                                SO   2

____________________  ____________________

Which of the above compounds is expected to have the highest boiling point?

 

When we looked at the series of compounds: H 2O, H2S, H2Se, H2Te, boiling point increased from H2S to H2Se to H2Te, but H2O had the highest boiling point of the four. Explain the trend and why H2O is an exception.

  

 

If, however, you look at the trend for the compounds: (H 3C)2O, (H3C)2S, (H3C)2Se, (H3C)2Te, then boiling point increases as you go down the periodic table and (H3C)2O is not an exception. Explain.

Watch Solution

Which of the following of each pair is expected to be more soluble in water?

CH3OH or CH3Br     SiO2 or H2CO3      C6H12 or C6H12O

a) CH3OH     SiO2       C6H12O6

b) CH3OH     H2CO3    C6H12O6

c) CH3Br       SiO2       C6H12

d) CH3Br       SiO2       C6H12O6

e) CH3OH     H2CO3    C6H12

Watch Solution

Choose the molecule or compound that exhibits dispersion forces as its strongest intermolecular force. 

A) CO

B) Cl2

C) HF

D) NaCl

E) All of these have intermolecular forces stronger than dispersion. 

Watch Solution

Place the following compounds in order of  increasing strength of intermolecular forces.

CO2      F2      NH 2CH3

 

A) F2  < NH 2CH 3 <  CO2

B) NH 2CH3  <  F2 <  CO2

C) CO2  < NH2CH3 <  F2

D) F2  <  CO2 <  NH2CH3

E) NH2CH3  <  CO2 <  F2

Watch Solution

The term “like dissolves like” is used to help explain why a solute dissolves in a given solvent. What property of the solvent and solute need to be alike for the solution to form?

a) The chemical composition.

b) The molecular weights.

c) The boiling points.

d) The lattice enthalpies.

e) The intermolecular bonds.

Watch Solution

Below are various rankings of intermolecular forces, which option correctly ranks the given forces from weakest to strongest?

a) dipole-dipole < ion-dipole < ion-induced dipole

b) dispersion < ion-induced dipole < dipole-induced dipole

c) dipole-dipole < hydrogen bonding < dipole-induced dipole

d) ion-induced dipole < dipole-dipole < hydrogen bonding

e) dipole-induced dipole < hydrogen bonding < ion-induced dipole

Watch Solution

What types of intermolecular forces exist between PH 3 and CO?

A. hydrogen bonding      

B. dispersion forces and hydrogen bonding      

C. dispersion forces

D. dipole-dipole and hydrogen bonding       

E. dispersion forces and dipole-dipole

Watch Solution

In general, intramolecular forces determine the __________ properties of a substance and intermolecular forces determine its __________ properties.

A. chemical, physical      

B. physical, chemical      

C. solution, intrinsic    

D. pressure, viscosity

Watch Solution

Which of the following compounds could not participate in hydrogen-bonding?

a) H2O

b) CH3NH2

c) CH3OH

d) CH3Cl

e) NH3

Watch Solution

London forces would be the strongest type of interaction between which of the following molecules in the gas phase?

a) NaCl

b) H2O

c) CaCl2

d) O2

e) HCl

Watch Solution

Water and ethyl alcohol (CH3CH2OH, the kind people drink) mix completely with one another. What are the strongest intermolecular forces that are responsible for attracting these molecules to each other in this solution?

a) ion-ion

b) induced dipole-induced dipole

c) dipole-induced dipole

d)  dipole-dipole

e) ion-dipole

Watch Solution

A solution of hydrochloric acid in water is often used to clean dirty toilets. What are the strongest intermolecular forces in this solution?

a) ion-ion

b) induced dipole-induced dipole

c) dipole-induced dipole

d) dipole-dipole

e ion-dipole

Watch Solution

"Sparkling water" is made by dissolving large amounts of carbon dioxide gas in ordinary water. What are the strongest types of intermolecular bonds between the carbon dioxide molecules and the water molecules in this mixture?

a) London forces

b) dipole-dipole forces

c) ion-dipole forces

d) dipole-induced dipole forces

e) ion-ion forces

Watch Solution

It is common to add Epson salts to bath water when one has been over exercising and has sore muscles. What is the primary intermolecular force that exists between magnesium sulfate, the primary in Epson salts, and the water in the bathtub?

a) dipole-dipole forces

b) ion-dipole forces

c) London forces

d) ion-ion forces

e) dipole-induced dipole forces

Watch Solution

What are the major attractive forces in an aliquot of pure carbon tetrachloride CCl 4?

a) dipole-induced dipole

b) dispersion

c) ion-ion

d) ion-dipole

e) dipole-dipole

Watch Solution

Which one of the following substances should exhibit hydrogen bonding in the liquid state?

            A)  PH3    B)  He    C)  H2S    D)  CH4    E)  CH3OH

Watch Solution

Which one of the following substances will have both dispersion forces and dipole-dipole forces?

            A)  Br2    B)  BCl3    C)  HCl    D)  H 2    E)  CO2

Watch Solution

Which of the responses includes all of the following that can form hydrogen bonds with water molecules?

(A) Na+      (B) CH 3COOH     (C) C2H6     (D) CH 3NH2

1) (A) and (B)

2) (A) and (C)

3) (B) and (C)

4) (B) and (D)

5) (C) and (D)

Watch Solution

On a relative basis, the weaker the intermolecular forces in a substance:

a) the greater its heat of vaporization

b) the more it deviates from ideal gas behavior.

c) the greater is its vapor pressure at a particular temperature

d) the higher is its melting point

e) none of these

Watch Solution

Which type of solid is held together only by hydrogen bonds?

A. molecular crystal

B. ionic crystal

C. network crystal

D. metallic crystal

E. several of the above

Watch Solution

The DOMINANT intermolecular force that causes gaseous HCl molecules to attract one another is

1. dipole-dipole

2. covalent

3. None of these is dominant.

4. Ionic

5. van der Waals

Watch Solution

A liquid in a test tube has a curved surface such that the edges touching the glass are higher than the surface at the center. This must mean that the cohesive forces are less than the adhesive forces.

 

1. False

2. True 

Watch Solution

Liquid hydrogen is used as one part of the booster fuel in the space shuttle. What type of forces exist between hydrogen molecules in liquid hydrogen?

1. a mixture of all these forces

2. dispersion forces

3. hydrogen bonding

4. dipole forces

Watch Solution

Which of the following exhibits hydrogen bonding?

1. H3COCH3

2. CH3NH2

3. CH3SH

4. CH3Cl

5. HCl

 

Watch Solution

The strongest intermolecular forces between LiF particles are

1. dipole-dipole forces

2. dispersion forces

3. hydrogen bonding 

4. ion-dipole interactions

Watch Solution

The strongest intermolecular forces between hydrogen sulfide (H 2S) molecules arise from 

1. dipole-dipole forces

2. dispersion forces

3. hydrogen bonding

4. ion-dipole interactions

5. disulfide linkages

Watch Solution

Which of the following has the strongest intermolecular forces?

1. F2

2. Ne

3. BrF

4. CO2

Watch Solution

In which of the following compounds will the molecules not form hydrogen bonds with each other?

 

Watch Solution

The major forces holding water molecules together in the liquid state are referred to as hydrogen bonds. These are really what kind of attractive forces?

a) dipole-induced dipole

b) dispersion

c) ion-ion

d) ion-dipole

e) dipole-dipole

Watch Solution

What are the major attractive forces between molecules in the “solution” in an average soda can which contains primarily water and dissolved carbon dioxide?

a) dipole-induced dipole

b) dispersion

c) ion-ion

d) ion-dipole

e) dipole-dipole

Watch Solution

What are the major attractive forces in an aliquot of pure carbon tetrachloride CCl 4?

a) dipole-induced dipole

b) dispersion

c) ion-ion

d) ion-dipole

e) dipole-dipole

Watch Solution

Which intermolecular force predominates in the condensation of water?

a. H-bonding 

b. Van der Waals

c. London

d. Ion-Ion

e. Dipole-ion

Watch Solution

Volatile liquids are described by all of the following except:

 

a. Volatile liquids are easily vaporized.

b. Volatile liquids have relatively high vapor pressures.

c. Volatile liquids have strong cohesive forces.

d. Volatile liquids have weak intermolecular forces.

e. All of these describe volatile liquids.

Watch Solution

As intermolecular forces get weaker, boiling point ____________, volatility ___________, surface tension ___________, vapor pressure ______________.

 

A. Increases, Decreases, Increases, Decreases

B. Increases, Increases, Decreases, Decreases

C. Decreases, Increases, Decreases, Increases

D. Decreases, Decreases, Increases, Increases

Watch Solution