Chemical Systems at Equilibrium

Question 1

What is a dissociation reaction in chemistry?

Answer 1

A dissociation reaction in chemistry refers to the process in which a compound breaks down into smaller components, typically ions, when it is dissolved in a solvent or subjected to certain conditions like heat.

In the context of ionic compounds, dissociation usually happens when the compound dissolves in water, and it separates into its constituent ions.

Question 2

What was Arrhenius’ theory?

Answer 2

He proposed that ions form when salts dissolve in water. This is why all aqueous solutions of salts conduct electricity.

He also theorized that what is common to all acids is that they release hydrogen ions to the water. Because all acids provide a common ion to the water, they all should share some common properties despite differences in their formulas.

All bases have common properties because they all provide the same ion, the hydroxide ion when dissolved in water.

Question 3

What are acid-base neutralization reactions?

Answer 3

One of the most important properties of acids and bases is that they can destroy each other by a reaction called acid-base neutralization. If an aqueous acid and an aqueous base are combined in exactly the right proportions, the resulting solution has no effect on litmus.

Acid-base neutralization reactions generally produce water and a salt.

According to Arrhenius, acid-base neutralization is simply the combination of a hydrogen ion with a hydroxide ion to produce a water molecule, thereby removing these ions from the solution.

Question 4

What is a Brønsted-Lowry acid?

Answer 4

Any substance that gives up a hydrogen ion or in other words, is a proton donor.

Question 5

What is a Brønsted-Lowry base?

Answer 5

Any substance that can accept a hydrogen ion, or in other words, is a proton accepter.

Question 6

What are polyprotic acids?

Answer 6

Polyprotic acids are acids that are capable of donating more than one proton (H⁺) per molecule during the process of dissociation.

Question 7

What are conjugate acid-base pairs?

Answer 7

A conjugate acid-base pair consists of two substances that differ by only one proton (H⁺). In an acid-base reaction, an acid donates a proton to become its conjugate base, while a base accepts a proton to become its conjugate acid. These pairs are directly related through the transfer of a proton in the reaction.

Key Concepts:
Acid: An acid is a substance that donates a proton (H⁺) in a reaction.
Base: A base is a substance that accepts a proton (H⁺) in a reaction.
Conjugate Acid: The species that is formed when a base gains a proton.
Conjugate Base: The species that is formed when an acid loses a proton.

Question 8

Solutions in which hydronium ion concentration is greater than the hydroxide ion concentrate are?

Answer 8

Acidic.

Question 9

Solutions in which the hydroxide ion concentration is greater than the hydronium ion concentration are?

Answer 9

Basic.

Question 10

What is Kw?

Answer 10

In chemistry, refers to the ionization constant of water, also known as the water dissociation constant. It represents the equilibrium constant for the dissociation of water into its ions.
At 25°C (298 K), 𝐾𝑤 has a value of approximately:
1.0×10^−14

Question 11

The pH of pure water is?

Answer 11

7.
The pH scale ranges from 0 to 14. A pH of 7 is neutral as in the case of distilled water. A solution with a pH below 7 is acidic; the smaller the pH, the more acidic the solution. Any solution with a pH greater than 7 is considered basic; the higher the pH value, the more basic the solution.

Question 12

What is Ka?

Answer 12

In chemistry, refers to the acid dissociation constant. It is an equilibrium constant that quantifies the strength of an acid in a solution, specifically how well an acid dissociates (or ionizes) into its hydrogen ions (H⁺) and conjugate base.

Large Ka (greater than 1): Indicates that the acid dissociates almost completely in solution, meaning it is a strong acid.

Small Ka (less than 1): Indicates that the acid dissociates only partially, meaning it is a weak acid.

If Ka is very small (close to 0), the acid is almost undissociated in solution and thus very weak.

Question 13

What is a buffer?

Answer 13

A buffer solution resists changes in pH when small quantities of an acid or a base are added to it because a buffer solution contains both an acidic and a basic component. If any acid should be added to a buffer solution, the basic component would react with it. If any base should be added to a buffer solution, the acidic component would react with it.

Question 14

What do Keq numbers mean?

Answer 14

If greater than 1, more products are favoured.

If less than 1, more reactants are favoured.

If equal to 1, the concentrations of both reactants and products are similar.

Question 15

What does Keq mean?

Answer 15

Keq, or the equilibrium constant, is a value that expresses the ratio of the concentrations of products to reactants in a chemical reaction at equilibrium.

It’s a key concept in chemistry that helps determine the position of equilibrium and whether products or reactants are favored in a reaction.

Question 16

Keq cannot equal the states of?

Answer 16

Solid and liquid.

Species that exist in either the solid or liquid phase are not included in the equilibrium expression as their densities remain constant regardless of the amount. Since concentration is a measure of mass per volume, solids and liquids can be considered as constants and are omitted from the equilibrium law expression.

Question 17

What is Le Chatelier’s Principle?

Answer 17

According to Le Chatelier’s Principle, if a dynamic equilibrium is disturbed by changing the conditions (such as concentration, temperature, or pressure), the system will adjust itself to counteract that change and restore a new equilibrium.

Question 18

What is a reaction quotient (Q)?

Answer 18

The reaction quotient (Q) is a value that helps predict the direction in which a reaction will proceed to reach equilibrium. It is calculated using the same formula as the equilibrium constant (Keq), but with the current concentrations or partial pressures of the reactants and products, rather than those at equilibrium.

Question 19

How do you calculate equilibrium concentrations?

Answer 19

An I.C.E. table. I.C.E. being an acronym standing for Initial, Change, and Equilibrium.

Question 20

What is Ksp?

Answer 20

The solubility product constant (K_{sp}) is a specific type of equilibrium constant used to describe the solubility of sparingly soluble ionic compounds in water. It quantifies the extent to which a compound will dissolve to form ions in solution.

Question 21

Solubility changes with?

Answer 21

Although equilibrium concentrations remain constant, solubility changes with varying temperatures. For this reason, values are always reported with the temperature for that particular reaction.