Ch.4 - Chemical Quantities & Aqueous ReactionsWorksheetSee all chapters
All Chapters
Ch.1 - Intro to General Chemistry
Ch.2 - Atoms & Elements
Ch.3 - Chemical Reactions
BONUS: Lab Techniques and Procedures
BONUS: Mathematical Operations and Functions
Ch.4 - Chemical Quantities & Aqueous Reactions
Ch.5 - Gases
Ch.6 - Thermochemistry
Ch.7 - Quantum Mechanics
Ch.8 - Periodic Properties of the Elements
Ch.9 - Bonding & Molecular Structure
Ch.10 - Molecular Shapes & Valence Bond Theory
Ch.11 - Liquids, Solids & Intermolecular Forces
Ch.12 - Solutions
Ch.13 - Chemical Kinetics
Ch.14 - Chemical Equilibrium
Ch.15 - Acid and Base Equilibrium
Ch.16 - Aqueous Equilibrium
Ch. 17 - Chemical Thermodynamics
Ch.18 - Electrochemistry
Ch.19 - Nuclear Chemistry
Ch.20 - Organic Chemistry
Ch.22 - Chemistry of the Nonmetals
Ch.23 - Transition Metals and Coordination Compounds

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

Understanding Electrolytes

Concept #1: The Classification of Electrolytes


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 #2: The Strong Electrolytes


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 #3: The Weak Electrolytes


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 #4: The Non-Electrolytes


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 #1: 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)

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

Practice: 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