Electrolytes

Electrolytes are compounds that can conduct electricity once they are dissolved in a solvent. 

Understanding Electrolytes

Concept: The Classification of Electrolytes

1m
Video Transcript

Electrolytes are basically the ions that are present in a solution after the compound dissolves in the solvent. Those ions will conduct electricity, so we're going to say whenever we add a solute into a solvent, three outcomes are possible.
The solute can completely dissolve and if it completely dissolves, then it's called a strong electrolyte. It breaks up into its ionic forms. The solute could partially dissolve and if it partially dissolves, that means some of it is going to maintain its molecular structure. Those are considered weak electrolytes. Then finally, the solute will not dissolve at all. When it doesn't dissolve at all, it's known as a non-electrolyte. Those are the three categories for electrolytes. 

Whenever you add a solute to a solvent there are three possible outcomes: the solute dissolves completely, dissolves partially or doesn't dissolve at all into ions. 

Concept: The Strong Electrolytes

6m
Video Transcript

If we take a look here, we can actually classify different types of compounds as either being strong electrolytes, weak electrolytes or non-electrolytes. Let's look at the strong electrolytes.
Our strong electrolytes belong into three categories. First things first, we have our strong acids. Strong acids are considered strong electrolytes. So they break up completely when they're dissolved in water. Examples here, we have HCl, we have a blank and then we have HI.
Now if you take a look at your periodic table, you'll notice that chlorine and iodine are both in the same group number. Both of them are in Group 7A. Take a look at your periodic table, what element is in between chlorine and iodine? It will be Br, so HBr is considered a strong acid as well.
HF is not considered a strong acid. It's actually considered a weak acid. It's because it possess hydrogen bonding. You'll learn about that later on. But just realize because of the hydrogen bonding it has present in it, HF is a considered a weak acid.
So HCl, HBr, HI so far, HNO3 is another strong acid, then the last three will be H2SO4, HClO4, and HClO3. Those are considered your seven major types of strong acids.
Now the second type of strong electrolyte we can have our strong bases. Now, we're going to say strong bases fit into two major types of categories up to this point. Later on, when we learn more in depth analysis on acids and bases, we're going to open up two more and more different types of acids and bases. For this point right now, this is all you really need to know when it comes to electrolytes.
For strong bases, Group 1A metals when they're combined with OH-, H-, O2- or NH2-, they will be strong bases and they'll be considered strong electrolytes. Remember what's the charge of Group 1A ions? They're all +1. So we combine each of these with one of these ions.
Na+ OH-, their charges just cancel out and you get NaOH. Here the charges just cancel out, you get CsH. The two from here is going to move down here. The one from here is going to move over here, so this would be K2O. Then, finally, you'd have LiNH2. So all of these are good examples of strong bases. Now, any one of these four ions could combine with any one of the Group 1A metals to create a strong base.
Now, the next one we have Group 2A metals. Here we're going to say Ca or lower when they're combined with these same four ions creates strong bases. But what do I exactly mean by calcium or lower? Group 2A on our periodic table has beryllium, magnesium and then, calcium you have, strontium and barium. I'm saying calcium and lower, so calcium, strontium, and barium, when they're with one of these guys they create a strong base. All of them are in Group 2A, so they're all +2.
If we combine some of them with some of these ions -- just remember the two from here will move down here, the two from here will move over here, the two from here will move over here. So, we get CaOH2, SrH2, Ba(NH2) 2. These are all common examples of strong bases from Group 2A.
Finally, we're going to say soluble ionic compounds are considered strong electrolytes. What do I mean in this section? Here, this is basically ionic compounds that follow the solubility rules. For example, we're going to say that Na is a Group 1A metal. Group 1A ions are soluble with whoever they're with. So I could have Na with NO3. This will break up into Na+ plus NO3-, breaks up fully into its ions, so it's a strong electrolyte. We could also have LiCl. Group 1A metal, Cl is soluble with everyone also except for certain metals.
So, our three categories for strong electrolytes are strong acids, strong bases and those that follow the rules for being soluble when we look at the solubility rules. 

Strong Electrolytes break up into ions completely and are grouped into 3 categories: Strong Acids, Strong Bases and Soluble Ionic Compounds

Concept: The Weak Electrolytes

2m
Video Transcript

Our weak electrolytes fall into two categories: weak acids and weak bases. Here we have HF, which is hydrofluoric acid, then we could have acetic acid, then you could have a nitrous acid.
Remember we've talked about naming acids already, so these names should not be new to you because we did go over certain examples when we've covered these very same weak acids and strong acids, weak bases, strong bases. Another example: carbonic acid and then phosphoric acid.
Now, for the weak bases, remember we said for Group 2A metals, calcium and lower, when they're with OH-, H-, NH2- or O2-, they form strong bases. But these guys up here, when they're connected to OH-, they're going to form weak bases, so that's how we came up with Be(OH) 2 and Mg(OH) 2. We also have NH3, ammonia, and then we have NH4OH, this is ammonium hydroxide. That's considered a weak base also. 

Weak Electrolytes partially break up into ions and are grouped into 2 categories: Weak Acids and Weak Bases

Concept: The Non-Electrolytes

2m
Video Transcript

Our non-electrolytes are just our molecular compounds, so our covalent compounds. They don't break up in solution. Remember covalent compounds are just non-metals with nonmetals.
Here, two good examples are glucose and fructose. If they end with -ose, they're considered covalent sugars: glucose, fructose, galactose, maltose. For those of you who are biology majors, you should remember this, so if you end with -ose, you’re covalent sugar and therefore you're a non-electrolyte.
We also have CH3OH, this is called methanol. If you end with the name -ol, -ol in the name, that means you're an alcohol. Alcohols are considered to be organic or molecular compounds. They're non-electrolytes too. So your teacher might say the name -ol at the end. Just remember that’s the same thing, same type of compound as methanol.
Finally, another non-electrolyte would be water. Water doesn't break down into other fragments. It just stays water. It's the one that does the dissolving. It itself does not dissolve into smaller pieces. 

Non-Electrolytes do NOT break up into ions at all and are commonly referred to as molecular compounds

Example: Each of the following reactions depicts a solute dissolving in water. Classify each solute as a strong electrolyte, a weak electrolyte or a non-electrolyte. 

a.  PbSO4 (s) → PbSO4 (aq) 

b.  HC2H3O2 (aq)  ⇌  H+ (aq) + C2H3O2 (aq)

c.  CaS (s) → Ca2+(aq) + S2- (aq)

d.  Hg (l) → Hg (aq)

5m

Based on different classifications of electrolytes we can expand to other compounds. 

Problem: Classify each of the following solutes as either a strong electrolyte, a weak electrolyte or a non-electrolyte.

a. Perbromic acid, HBrO4

b. Lithium chloride, LiCl

c. Formic Acid, HCO2H

d. Methylamine, CH3NH2

e. Zinc bromide, ZnBr2

f. Propanol, C3H8OH


6m

Electrolytes Additional Practice Problems

K2SO4 is a strong electrolyte. 

Determine the concentration of each of the individual ions in a 0.650 M K2SO4 solution. 

[K+] = 

[SO42-] = 

Watch Solution

Which compound is an electrolyte?

a. C6H12O6
b. C12H22O11
c. CH3CH2OH
d. CH3COOH
 

Watch Solution

Classify each of the following as a strong electrolyte or non electrolyte.

MgBr2, C12H22O11, Na2CO3, KOH

Watch Solution

Classify these compounds as strong electrolytes, weak electrolytes, or nonelectrolytes. 

HBr, H2CO3, FeCI2

Watch Solution

Classify these compounds as strong electrolytes, weak electrolytes, or nonelectrolytes.

AgClO3 

NH3 

Fe(OH)2 

NaOH

H2SO

HClO

HNO

HCl

Zn(NO3)2

Watch Solution

Classify these compounds as strong electrolytes, weak electrolytes, or nonelectrolytes.

HBr, FeCl2, H2CO3

Watch Solution

Classify these compounds as strong electrolytes, weak electrolytes, or nonelectrolytes.

H2SO4, (NH4)2S, HClO

Watch Solution

Which of the following statement(s) is/are correct?

   i. KBr, HI, and Mg(OH) 2 are strong electrolytes

   ii. NaH, CH 3COOH, and NH3 are weak electrolytes

   iii. C3H7OH, C6H11O6, and O2 are non-electrolytes

A) i only

B) ii only

C) iii only

D) i and ii

E) i and iii

Watch Solution

Which of the following water soluble compounds does not conduct an appreciable current in aqueous solution by means of ion movement ?

a. CH3COOH (acetic acid)

b. NaNO3

c. CH3CH2OH (ethyl alcohol)

d. KCl

e. HF

Watch Solution

Which of the following is not a weak electrolyte?

a. CH3COOH

b. HF

c. NH3

d. HNO3

e. all these are weak electrolytes

Watch Solution

Which of the following is a weak electrolyte?            

a) HBr           

b) KOH         

c) CH3OH                 

d) RbOH       

e) HF

Watch Solution

Which of the following compounds is a weak acid, or weak electrolyte?

a) HI

b) HCl

c) CH3CO2H

d) HClO4

e) HNO3

Watch Solution

Salts may be either strong or weak electrolytes. Which of the following is considered to be the salt?

a) HF

b) C12H22O11

c) AgBr

d) HC2H3O2

e) HBrO

Watch Solution

Which one of the following compounds is a nonelectrolyte when dissolved in water?

a) calcium chloride (CaCl2)

b) potassium hydroxide (KOH)

c) sodium acetate (NaCH3CO2)

d) acetic acid (CH3CO2H)

e) glucose (C6H12O6)

Watch Solution

What is the non-electrolyte among the set?

a) NaCl

b) CH3CH2CH2OH

c) LiOH

d) BaCl2

e) K2O2

Watch Solution

Which of the following is considered a STRONG electrolyte?

a) NH4NO3
b) C12H22O11
c) PbBr2
d) HC2H3O2
e) CH3SH

Watch Solution

Which of the following aqueous solutions would not conduct electricity at all?

a) HNO3

b) CaCl2

c) H2CO

d) KOH

e) H3PO4

Watch Solution

Which of the following compounds is a non-electrolyte?

A. NaCl

B. Na2CO3

C. KBr

D. C2H6O

E. HCl

Watch Solution

Which of the following statements is/are INCORRECT?

1. Water soluble ionic compounds, such as NaCl, are all strong electrolytes.

2. Some acids are strong acids while others are weak.  The acids HF and HNO2 are examples of strong acids.

3. Only Group 1 (1A) hydroxides are soluble in water.

 

a. 1 and 2 only

b. 2 and 3 only

c. 1 and 3 only

d. 1 only or 2 only or 3 only

e. 1, 2, and 3

 

Watch Solution

Identify each of the following substances as strong electrolyte, weak electrolyte, or nonelectrolyte:

A) Ba(NO3)2,

B) Ne,

C) NH3,

D) NaOH,

Watch Solution

Which of the following is a strong electrolyte?     

A) CH4           

B) NH4NO3    

C) H2O           

D) CH3OH                 

E) CCl4

Watch Solution

HCl, KOH,LiCl, and KI are ALL classified as      

A) nonelectrolytes.     

B) weak electrolytes.             

C) strong electrolytes.     

D) acids.

Watch Solution

Electrolyte Classifications

Watch Solution

The dissolution of a compound is given by the reaction below: 
Identify each of the following solutions as either electrolytic, weakly electrolytic or non-electrolytic. 

Watch Solution

Which of the following statements is/are correct? 

a)    Nitric acid is a weak electrolyte

b)    Strontium hydroxide is a strong electrolyte

c)    CH3CH2OH  is a weak electrolyte

d)    NaCl is a non-electrolyte

e)    Hydrobromic acid is a weak electrolyte

Watch Solution

Which of the following is considered a STRONG electrolyte?

a) NH4NO   b) C12H22O11        c) PbCl       d) HC2H3O       e) CH3OH

Watch Solution

Which of the following is  NOT a strong electrolyte?

a) LiOH        b) CaCl2        c) MgCO3        d) NaC2H3O2         e) Li2SO4

Watch Solution

Which of these compounds is a strong electrolyte?

A)  H2O

B)  O2                    

C)  H2SO4             

D)  C6H12O6 (glucose)     

E)  CH3COOH (acetic acid)

Watch Solution

HCl, HI, H2SO4, LiCl, and KI are all classified as      

A) nonelectrolytes     

B) weak electrolytes              

C) strong electrolytes             

D) strong acids

Watch Solution

Which of the following would be a strong electrolyte:

i. KCIO3
ii. HI
iii. HC2H3O2

A. i only
B. iii only
C. i and ii
D. i and iii
E. ii and iii

Watch Solution

Which of the following aqueous solutions would be a strong electrolyte:

a. HBrO

b. HF

c. NH3

d. C6H6O

e. HCI

Watch Solution

Which of the following solutions will have the highest electrical conductivity?

A) 0.045 M Al 2(SO4)3

B) 0.050 M (NH 4)2CO3

C) 0.10 M LiBr

D) 0.10 M NaI

E) 0.10 M KF

Watch Solution

Explain how a strong electrolyte, a weak electrolyte, and a nonelectrolyte differ.

Watch Solution

In a sugar solution, molecules dissolve as __ . 

A. individual ions

B. intact molecules

C. strong electrolytes

D. redox components

Watch Solution

Which of the following is a strong electrolyte?

A. Glucose (C12H22O11)

B. Acetic acid (HC2H3O2)

C. Methane (CH4)

D. Hydrochloric acid (HCl)

Watch Solution

Which of the following is a weak electrolyte in aqueous solution?

a) HF

b) NaF

c) HCl

d) KCl

Watch Solution

Partial ionization is associated with which of the following?

A. Strong acids

B. Nonelectrolytes

C. Weak acids

D. Strong electrolytes

Watch Solution

Which of the following is a strong electrolyte?

A. Glucose (C12H22O11)

B. Acetic acid (HC2H3O2

C. Methane (CH4

D. Hydrochloric acid (HCI) 

Watch Solution

Which of the following are strong electrolytes?

i) HBr

ii) HC2H3O2

iii) NH3

iv) KNO3

a) i, iv

b) i, iii, iv

c) i, ii, iii, iv

d) i, ii, iv

e) ii, iv

Watch Solution

Which of the following are not electrolytes:

a. Li2S

b. BaCl2

c. K2C2O4

d. C3H8O3

e. SrSO4

Watch Solution

Which of the following aqueous solutions is a nonelectrolyte? 

A. HF

B. NaClO

C. C12H22O11 

D. NH3

E. FeCl3

Watch Solution

Which of the following is both a weak acid and a weak electrolyte?

A. HF

B. NH3

C. CH3OH

D. HCl 

E. HNO3

Watch Solution

Which of the following is a weak electrolyte?

1. CaCl2(aq)          

2. HNO3(aq)         

3. C2H6O(aq)         

4. H3PO4(aq)

Watch Solution

Which of the following aqueous solutions is a nonelectrolyte?

A. HF

B. NaClO4

C. C12H22O11

D. NH3

E. FeCl3

Watch Solution

Three different substances, A2X, A2Y, and A2Z, were dissolved in water with the following results. (Water molecules are omitted for clarity.) Which is the strongest electrolyte, and which is the weakest?

Watch Solution

Which of the following is considered a STRONG electrolyte?

A. CH3SH

B. NH4NO3

C. C12H22O11

D. HC2H3O2

E. all of the above

Watch Solution

Choose the statement below that is TRUE.

A. A molecular compound that does not ionize in solution is considered a strong electrolyte.

B. A strong acid solution consists of only partially ionized acid molecules.

C. A weak acid solution consists of mostly non-ionized (or non-dissociated) acid molecules.

D. The term "weak electrolyte" means that the substance is inert.

E. The term "strong electrolyte" means that the substance is extremely reactive.

Watch Solution

Potassium phosphate, K3PO4, sodium iodide, Nal, magnesium chloride, MgCl 2, methanol, CH3OH, and ammonium chloride, NH4Cl, are soluble in water. Which would be the strongest electrolyte per mole of dissolved solute?

a) K3PO4

b) Nal

c) MgCl2

d) CH3OH

e) NH4Cl

Watch Solution

Which of the following is a soluble, strong base?

a. Sr(OH)2

b. NH2OH

c. Fe(OH)3

d. Cr(OH)3

e. Be(OH)2

Watch Solution