Electrolytes - Online Tutor, Practice Problems & Exam Prep

Electrolytes are substances that conduct electricity when they form ions in a solution or when melted. Strong electrolytes, such as strong acids (hydrochloric acid, hydrobromic acid, hydroiodic acid, chloric acid, bromic acid, nitric acid, perchloric acid, perbromic acid, periodic acid, and sulfuric acid), strong bases (compounds of Group 1A and 2A metals like lithium, sodium, potassium, rubidium, cesium, calcium, strontium, and barium with hydroxide, hydride, amide, or oxide ions), and soluble ionic compounds, dissociate completely into ions. Weak electrolytes, which include weak acids not classified as strong and weak bases such as beryllium hydroxide, magnesium hydroxide, ammonium hydroxide, and neutral amines, only partially ionize. Non-electrolytes, like water, sugars, and alcohols, do not ionize at all in solution. The solubility rules help determine the strength of an electrolyte based on the compound's ability to dissolve and ionize, which is crucial for understanding chemical reactions and properties.

Categories of the Electrolytes

Now electrolytes represent compounds that conduct electricity when entering their ionic forms when dissolved or melted. Now recall conductivity is a physical property that deals with the ability of electric current to flow through a material. Now we have strong electrolytes, weak electrolytes and non electrolytes. With strong electrolytes, we say they represent solutes that completely or totally dissolve into ions when placed in a solvent.

So for example, let's say we had AB solid here. If there were a strong electrolyte, it would break up 100% to give us a positive aqueous. When you are an ion in solution your aqueous plus B minus aqueous, we're going to say strong electrolytes are strong acids, strong bases and are soluble ionic compounds. Remember, we know our soluble ionic compounds from the solubility rules.

Now if we take a look here, let's look at our strong acids first. For strong acids, we classify them either as Halo acids, trioxide acids or Tetra oxide acids. So our Halo acids that are strong are hydrochloric acid, hydrobromic acid and hydroiodic acid. Here, if we look at the periodic table, we have our strong assets here. So we said that HCL is 1 HBR's one and HI is another.

Trioxides mean they possess 3 oxygens, so chloric acid is HClO3, HBrO3 and HNO3. So here notice that there's no HIO3. Hil 3 does not constitute a strong acid, so here HNO3 would be a strong one, and then here we'd have HClO3 and then we have HBrO3. And then here our Tetra oxides have 4 oxygens involved. So this would be HClO4 per bromic acid is HBrO4 per iota acid is HIO4, and then finally sulfuric acid which is H2SO4.

So placing them here on the periodic table, we see the way that our strong acids shape different sections of the periodic table. So keep in mind these are all the strong acids that exist. For those of you who carry on into later, stronger, or like more difficult chemistries, these strong acids will make an appearance again, so keep them in mind when asked to discuss questions dealing with strong assets.

Electrolytes Example 1

Here it says provide the equation when sulfuric acid dissolves in a solvent. Sulfuric acid is a strong acid, so if we're talking about its complete dissociation, we're going to say here H2SO4 and we're going to break it up into its ions. It possesses 2H+ aqueous ions plus SO42- aqueous ions sulfate ion.

So here we'd say sulfuric acid will produce 2H+ aqueous plus SO42-. When we get into later chapters on acid and based chemistry, we'll learn further that this acid actually doesn't lose both hydrogen's at the same time, H+ it actually loses them in stages.

But this early on in chemistry just realized that overall, if this were to completely break up into ions, it would break up into two H+ ions and 1 sulfate ion.

Electrolytes Concept 2

Here we're going to say when group 1A and 2A metals combined with the following anions, they form strong bases. So the anions include hydroxide ion which is OH-, hydride ion, which is H-, the amide ion which is NH2- and the oxide ion which is O2-. The group 1A and 2A metals include we're going to have here lithium, sodium, potassium, rubidium and cesium. And then in Group 2A we're going to have calcium, strontium and barium.

So it's just the ones that I've written in which will be the metals when they combine with these four negative ions will create a strong base. So here for hydroxide. So let's say I took lithium ion and hydroxide ion and then I took calcium ion and hydroxide ion. So remember with charges when the numbers are the same, they cancel out. So this would just be LiOH lithium hydroxide here the numbers are different, There's a 2 here and A1 here. So two would come here and one would come here. That two is for all of the calcium hydroxide. All of the hydroxide ions are to be Ca(OH)2 hydride.

So let's say I took Na+ and H-. Here the numbers are the same, so they just cancel out to give me NaH, which is sodium hydride. Here let's say we had Sr2+ and H-. Again, the numbers are different. When they're different, they crisscross. So 2 from here would come here and one from here would come here to give me strontium hydride. Then we have amide ion. So let's say we did potassium with NH2-. That would give me potassium amide here. If we have barium with the amide ion, the numbers are different. So two would come here and one would come here. So this would be barium amide, so Ba(NH2)2 and then we have oxide.

So let's say we did Cs+ and O2-. The numbers are different. So what happens? They crisscross, one comes here, 2 comes here. So this would be Cs2O cesium oxide. And then let's say we had Ca2+ and O2-. Here the numbers are the same, so they don't crisscross, they just cancel out. So calcium oxide. So here we're just looking at different combinations of the metals that I have from groups 1A and 2A in blue mixed with one of these negative ions. Doing that will form a strong base. Remember, as a result of being a strong base, you are a strong electrolyte.

Which of the following represents a strong base?

• A. Mg(OH)₂
• B. CH₄
• C. H₂
• D. CsH
• E. CaOH

Electrolytes Concept 3

Here we're going to say that weak electrolytes represent solutes that partially dissolve into ions when placed into solve it. So here we have AB solid. To show that it's a weak electrolyte, we use double sided arrows to show that not all of AB dissolves into ions. So he would get Aq+B-q.

Very little of these ions would actually be forming because again it's a weak electrolyte. We're going to say here that weak electrolytes are either weak acids or weak bases. Now for weak acids, if an acid is not strong, then it is automatically going to be weak.

So the strong acids that we examined earlier are the strong acids. You need to remember if you see an acid and it's not one of those that we discussed, by default it is a weak acid and therefore it is a weak electrolyte.

Electrolytes Example 2

Here it says which of the following represents a weak binary acid and therefore a weak electrolyte. So remember, a binary acid does not possess oxygen, so automatically all the ones with oxygen are out.

So we have HCL and HCN. So they both represent binary assets because of the lack of oxygen. But the one that's a weak electrolyte would have to be the one that is also a weak acid.

HCL is one of our strong acids, so it would be a strong electrolyte. So by default, HCN, which is hydrocyanic acid, would be our weak binary acid and therefore our weak electrolyte.

Electrolytes Concept 4

So now, weak bases. Recall these patterns for identification, so they're a bit different. So we're going to have to just memorize them here. We're going to say weak bases include from Group 2A, beryllium hydroxide and magnesium hydroxide. And then also we have ammonium hydroxide or neutral amines.

Now what exactly is going to mean? Well, an amine is a compound that contains only nitrogen and hydrogen. For example, ammonia is an amine which is NH3, and an amine could be a compound that contains carbon, nitrogen and hydrogen. So an example here would be methylamine which is CH3NH2. These are two examples of amines; they can have either just nitrogen and hydrogen or carbon, nitrogen and hydrogen.

Now for non-electrolytes, these don't break up at all when put into a solvent, so they consist of molecular/covalent compounds. So those are interchangeable that never dissolve into ions. So here we'd have AB solid and when I throw it into water, it becomes surrounded by the water, so we'd say AB aqueous.

Non-electrolytes include water, sugars, and alcohols. So sugars are compounds with a molecular formula of CnH2N2On. Glucose is an example of this because it's C6H12O6. Sucrose is also a sugar. It doesn't fit this formula exactly as nicely, but it's C12H22O11. So with sugars at this point, these are the two most common ones that you would see.

Alcohols, on the other hand, are covalent compounds with C&H connected to OH. So methanol is CH3 connected to OH and phenol is C6H5 connected to OH. So in both, they have carbon and hydrogen in the beginning and then they have the OH following it up. OK, so the new OH here at the end. So again, water, sugars, and alcohols constitute non-electrolytes. They don't break up at all within our solvent.

Which of the following represents a non-electrolyte? 

• A. (CH₃)₂NH₂
• B. NaOH
• C. HIO₃
• D. C₂H₅OH
• E. CsNH₂

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)

• A. a) non-electrolyte; b) strong electrolyte; c) strong electrolyte; d) non-electrolyte
• B. a) non-electrolyte; b) weak electrolyte; c) strong electrolyte; d) non-electrolyte
• C. a) non-electrolyte; b) weak electrolyte; c) weak electrolyte; d) non-electrolyte
• D. a) weak electrolyte; b) strong electrolyte; c) strong electrolyte; d) non-electrolyte

Which of the following statements is true?  

• A. Perbromic acid, HBrO₄, represents a weak electrolyte
• B. Lithium chloride, LiCl, represents a non-electrolyte
• C. Formic acid, HCO₂H, represents a strong electrolyte
• D. Zinc Bromide, ZnBr₂, represents a strong electrolyte
• E. Propanol, C₃H₈OH, represents a weak electrolyte

Here’s what students ask on this topic:

What are electrolytes?

Electrolytes are minerals that carry an electric charge when dissolved in bodily fluids such as blood, urine, and sweat. These charged particles are essential for a variety of physiological processes. They include minerals like sodium, potassium, calcium, magnesium, chloride, phosphate, and bicarbonate.

These minerals help to regulate nerve and muscle function, hydrate the body, balance blood acidity and pressure, and help rebuild damaged tissue. For example, sodium and potassium are crucial for conducting electrical impulses in the nerve cells and muscles, including the heart muscle, which is vital for maintaining a regular heartbeat.

Electrolytes are typically obtained through your diet and are found in various foods and beverages. It's important to maintain a proper balance of electrolytes; too much or too little of these can lead to either an excess or a deficiency, both of which can cause health issues. For instance, an imbalance can result in symptoms like muscle cramps, fatigue, nausea, and even more severe conditions like arrhythmias or disorders of the nervous system.

What are strong electrolytes?

Strong electrolytes are substances that completely dissociate into ions when they dissolve in water. This means that when a strong electrolyte is dissolved in water, it breaks apart into its constituent cations and anions, which are then uniformly distributed throughout the solution. Because of this complete dissociation, strong electrolytes are very good conductors of electricity in aqueous solution.

Examples of strong electrolytes include most salts, like sodium chloride (NaCl), strong acids such as hydrochloric acid (HCl), and strong bases like sodium hydroxide (NaOH). When these compounds are in solution, they are present entirely as ions, and there are no undissociated molecules of the compound left in the solution. This characteristic is what distinguishes strong electrolytes from weak electrolytes, which only partially dissociate in solution, resulting in a mixture of ions and undissociated molecules.

How can strong and weak electrolytes be identified?

Strong electrolytes are substances that completely dissociate into ions when dissolved in water, resulting in a solution that conducts electricity very well. Examples include most salts, strong acids like hydrochloric acid (HCl), and strong bases like sodium hydroxide (NaOH).

Weak electrolytes, on the other hand, only partially dissociate into ions in solution, which means they produce a relatively low concentration of ions and, consequently, conduct electricity poorly. Examples of weak electrolytes include weak acids like acetic acid (CH₃COOH) and weak bases like ammonia (NH₃).

To identify whether a substance is a strong or weak electrolyte, you can:

1. Check its chemical formula and categorize it as a strong acid, strong base, salt (typically strong electrolytes), or weak acid/base (typically weak electrolytes).
2. Measure the electrical conductivity of its aqueous solution; a high conductivity indicates a strong electrolyte, while low conductivity suggests a weak electrolyte.
3. Look for the degree of ionization or dissociation in chemical reference materials; near 100% dissociation indicates a strong electrolyte, while significantly less reflects a weak electrolyte.

What are weak electrolytes?

Weak electrolytes are substances that partially dissociate into ions when they dissolve in water. Unlike strong electrolytes, which completely break apart into ions, weak electrolytes only do so to a limited extent, resulting in a relatively low concentration of ions in solution. This partial ionization is a reversible process, meaning the ions can recombine to form the original compound.

Examples of weak electrolytes include weak acids, like acetic acid (found in vinegar), and weak bases, such as ammonia. When these substances dissolve in water, only a small percentage of the molecules ionize to produce hydrogen ions ($H^{+}$) or hydroxide ions (${\mathrm{OH}}^{-}$), respectively. The presence of these ions allows weak electrolytes to conduct electricity, but not as well as strong electrolytes, since the number of charge carriers in the solution is less.

The degree of ionization of a weak electrolyte is often represented by an equilibrium constant ($K_a$ for weak acids or $K_b$ for weak bases), which quantifies the extent to which the compound forms ions in solution. Understanding weak electrolytes is important in various fields, including chemistry, biology, and environmental science, as they play key roles in many biological processes and environmental systems.