Chemistry: Acids and Bases Fundamentals

Which statement accurately defines a Lewis acid?

What is the correct expression for the equilibrium constant K in the context of proton transfer?

A strong acid is characterized by which of the following?

In the context of acid-base equilibria, what role does water generally play?

Which of the following compounds has the highest acidity based on pKa values?

What is true about conjugate acids and bases?

Which statement is incorrect regarding the relationship between pH and hydronium ion concentration?

What describes a polyprotic acid?

Which of the following statements about activities in dilute solutions is true?

How would you describe the primary function of a Brønsted base?

Acids and Bases

Acids donate protons (H+)
Bases accept protons (H+)
Brønsted-Lowry definition: acids donate, bases accept protons
Lewis acids and bases: broader definition - acids accept electron pairs, bases donate electron pairs

Protons in Water

Protons in water are highly solvated
Represented by the hydronium ion (H3O+)

Conjugates

When an acid loses a proton, it forms its conjugate base
When a base gains a proton, it forms its conjugate acid
Acids can be neutral, cationic, or anionic
Bases can be anionic, neutral, or cationic

General Equilibrium for Proton Transfer

An acid transferring a proton to a base in water can be represented by a general equilibrium equation
Equilibrium constant (K) is determined by the activities of the components

Activity and Concentration

Activities in dilute solutions can be approximated by concentrations
Water activity is considered constant in dilute solutions

Acidity of Aqueous Solutions

Depends on the concentration of hydronium ions (H3O+)
Sørensen defined pH: pH = -log10 [H3O+]
pX = -log10 X for many functions

Acid Dissociation in Water

The acidity constant (Ka) measures the strength of an acid
Ka is determined by the equilibrium constant for the dissociation in water

pKa

pKa = -log10 Ka
Measure of acid strength
High Ka = low pKa = strong acid
Low Ka = high pKa = weak acid

Polyprotic Acids

Have multiple ionizable protons
Can donate protons in steps, each with a different pKa value

Examples

Water (H2O) can act as an acid or a base
H3O+ is a strong acid
Acetic acid (CH3CO2H) is a weak acid
Ammonium ion (NH4+) is a weak acid

This quiz covers essential concepts related to acids and bases, including definitions and characteristics as per the Brønsted-Lowry and Lewis theories. It also explores the behavior of protons in water, the formation of conjugate pairs, and the principles of chemical equilibrium. Test your understanding of these fundamental chemistry topics!