Arrhenius Acid and Base: Study with Video Lessons, Practice Problems & Examples

Acids and bases can be categorized using the Arrhenius definition, which states that an acid increases the concentration of H⁺ ions in an aqueous solution, while a base increases the concentration of OH^- ions. For example, HCl is an Arrhenius acid as it dissociates in water to produce H⁺ and Cl^-, and NaOH is an Arrhenius base as it produces Na⁺ and OH^-. This broad definition, however, does not account for acid-base behavior outside of aqueous solutions.

Arrhenius Acids & Bases Concept 1

Hey guys, in this new video, we're going to take a look at a particular type of acids and bases. Now, we know that there are 2 types of acids. There are binary acids and oxy acids. And we know how to identify bases. Now, just realize that there are going to be 3 types of categories for acids and bases. The first one being Arrhenius. Now we're going to say the most general definition for acids and bases was developed by Arrhenius near the end of the 19th century. We're going to say according to him, we're going to say that the H⁺ cation and the OH^- anion were the fundamental pieces that helped to identify acids and bases. But the thing with him is, his definition failed to describe what happens to acids and bases when we take them out of water. When we take them out of aqueous solutions, what happens? His definition failed to talk about that. Now, we're going to say according to his Arrhenius definition, it states that an acid is a compound that increases my concentration of H⁺ when dissolved in a solvent. The solvent being water. Because to him acids and bases only operated in aqueous environments. Water. So we're basically going to say an example of an Arrhenius acid is HCl. When it breaks down in water, it's going to give me H⁺ plus Cl^-. Now, because Arrhenius's definition for an acid applies to both strong and weak acids. Because if they can produce H⁺ then they're technically Arrhenius. Now, so the limitation here is that to him, if you didn't have an H involved, you couldn't be an acid. But we'll learn later that this is just the wrong way of looking at things. Okay? So, now that we know the definition for an acid, let's look at the definition for a base. We're going to say according to his definition, Arrhenius definition, a base is a compound that increases the concentration of OH^- when dissolved in a solvent. Now what we're going to say here is a good example we have is NaOH. When it dissolves in water, it gives me Na⁺ plus OH^-. If it didn't create any OH^- as a product then it couldn't be described as an Arrhenius base. Again, this definition is the broadest of the 3 definitions we're going to see. It was the earliest one developed that's why it's so broad. It's basically any compound with H positive or OH^-. We'll learn more and more definitions that are more precise to exactly what acids and bases are. Now that we've seen this, I want you guys to attempt to do these questions. You have to tell me, how do each of these compounds break up to give me my products? And based on the products, are they Arrhenius Bases, Arrhenius Acids, or maybe neither one? Good luck on the first one guys. And again, once you're done with it, come back. Click on the explanation button and watch a video of me explaining how to break it up and what exactly it is that we're breaking up.

Which ions are formed from the dissociation of the following compound?

• A. Sr(OH)₂ (s) → Sr²⁺ (aq) + 2 OH^-
• B. Sr(OH)₂ (s) → Sr²⁺ (aq) + OH^-
• C. Sr(OH)₂ (s) → 2 Sr⁺ (aq) + OH^-
• D. Sr(OH)₂ (s) → 2 Sr⁺ (aq) + 2 OH^-

Which ions are formed from the dissociation of the following compound?

• A.
• B.
• C.
• D. No reaction

Which ions are formed from the dissociation of the following compound?

• A.
• B.
• C.
• D.

Here’s what students ask on this topic:

What is the Arrhenius definition of an acid?

The Arrhenius definition of an acid states that an acid is a compound that increases the concentration of H⁺ ions in an aqueous solution. For example, hydrochloric acid (HCl) dissociates in water to produce H⁺ and Cl^- ions. This definition is limited to aqueous solutions and does not account for acid behavior in non-aqueous environments.

What is the Arrhenius definition of a base?

The Arrhenius definition of a base states that a base is a compound that increases the concentration of OH^- ions in an aqueous solution. For instance, sodium hydroxide (NaOH) dissociates in water to produce Na⁺ and OH^- ions. This definition is also limited to aqueous solutions and does not describe base behavior outside of water.

What are the limitations of the Arrhenius definition of acids and bases?

The main limitation of the Arrhenius definition is that it only applies to aqueous solutions. It does not account for acid-base behavior in non-aqueous environments. Additionally, it restricts acids to compounds that produce H⁺ ions and bases to those that produce OH^- ions, excluding other substances that can act as acids or bases under different definitions.

Can you provide an example of an Arrhenius acid and explain its dissociation in water?

An example of an Arrhenius acid is hydrochloric acid (HCl). When HCl is dissolved in water, it dissociates completely into H⁺ and Cl^- ions. The dissociation can be represented by the equation:

${\mathrm{HCl}}_{}(aq)\to H_{}+{\mathrm{Cl}}_{}-$

Can you provide an example of an Arrhenius base and explain its dissociation in water?

An example of an Arrhenius base is sodium hydroxide (NaOH). When NaOH is dissolved in water, it dissociates completely into Na⁺ and OH^- ions. The dissociation can be represented by the equation:

${\mathrm{NaOH}}_{}(aq)\to {\mathrm{Na}}_{}+{\mathrm{OH}}_{}-$

How does the Arrhenius definition differ from other acid-base definitions?

The Arrhenius definition is the most restrictive, as it only considers acids and bases in aqueous solutions. In contrast, the Brønsted-Lowry definition describes acids as proton donors and bases as proton acceptors, applicable in both aqueous and non-aqueous environments. The Lewis definition is even broader, defining acids as electron pair acceptors and bases as electron pair donors, encompassing a wider range of chemical reactions.