Lecture Notes on Chemical Equilibrium and Acid-Base Chemistry

These flashcards cover key concepts regarding chemical equilibrium, acid-base reactions, pH calculations, and properties and definitions of acids and bases.

What is true concerning chemical equilibrium?

Forward and reverse reactions are occurring at the same rate; K is the ratio of [products] / [reactants] at equilibrium; Ratefwd = RateRev; K values vary greatly; Equilibrium can be disturbed by adding/removing reagents, changing pressure/volume, or adding/removing heat.

What is the value of ∆n for the reaction Cl2(g) + H2(g) ⇌ 2 HCl(g)?

0

What happens when C is removed from the reaction 2 A (g) + B (g) ⇌ 2C (g)?

The reaction shifts right to produce more C.

How does adding heat affect the reaction 2 A (g) + B (g) ⇌ 2C (g) with ∆Hrxn = -126 kJ/mol?

The reaction will shift left to absorb heat.

What is the pH scale used for?

To express the concentration of hydronium ions [H3O+] in a solution.

What does a pH value of 7 indicate?

The solution is neutral with [H3O+] = [OH-].

What is the formula to convert pH to [H3O+]?

[H3O+] = 10^-pH.

What defines a strong acid?

A strong acid completely dissociates into ions in water.

What is the relationship between Ka and pKa?

Lower pKa means higher Ka, indicating a stronger acid.

What is the definition of a Brønsted-Lowry acid?

A substance that donates H+ ions.

What is a conjugate acid-base pair?

Two substances that differ by one proton (H+).

What is the autoionization equation of water?

2 H2O(l) ⇌ H3O+(aq) + OH-(aq).

What is the formula for calculating the ion product constant of water, Kw?

Kw = [H3O+][OH-].

What is the pKa value?

A logarithmic way of expressing the acid dissociation constant Ka.

What is the dissociation constant Kb for a base?

A measure of the strength of a base; Kb = [BH+][OH-] / [B].

How does the strength of an acid affect its ability to donate a proton?

A stronger acid has a higher tendency to donate its proton.

Define polyprotic acids and their characteristics.

Acids that can donate more than one proton, where successive dissociations become increasingly difficult.

What is a weak acid?

An acid that only partially dissociates in solution.

What affects acid strength in oxoacids?

I. The electronegativity of the central atom. II. The number of oxygen atoms bonded to the central atom.

How does the presence of hydrated metal ions affect pH?

Some hydrated metal ions are weak acids and can lower the pH of the solution.

What happens to the pH of a solution from a salt with anion from a weak acid?

It produces a basic solution.

What is the dissociation reaction of nitrous acid (HNO2)?

HNO2 (aq) + H2O(l) ⇌ H3O+(aq) + NO2-(aq).