Acids, Bases, and Equilibrium Study Guide – General Chemistry

Q1. Match descriptions to Acid, Base, or Both

Background

Topic: Properties of Acids and Bases

This question tests your understanding of the unique and shared properties of acids and bases, including their behavior in solution and their chemical characteristics.

Key Terms:

• Acid: Substance that donates protons (H+) or increases H+ concentration in solution.

• Base: Substance that accepts protons or increases OH- concentration in solution.

• Both: May share properties such as being electrolytes or reacting with indicators.

Step-by-Step Guidance

1. Review the definitions of acids and bases according to Arrhenius and Bronsted-Lowry theories.

2. Identify properties unique to acids (e.g., sour taste, react with metals, produce H+ ions).

3. Identify properties unique to bases (e.g., bitter taste, slippery feel, produce OH- ions).

4. List properties common to both (e.g., conduct electricity, change color of indicators).

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Q2. Recognize the ions produced when an acid or base ionizes in solution

Background

Topic: Ionization of Acids and Bases

This question tests your ability to identify the ions formed when acids and bases dissolve in water.

Key Terms:

• Acid ionization: Produces H+ (or H3O+) ions.

• Base ionization: Produces OH- ions.

Step-by-Step Guidance

1. Recall the Arrhenius definition: Acids increase H+ concentration, bases increase OH- concentration.

2. Write the general ionization equation for an acid: $\text{HA} + \text{H}_2\text{O} \rightarrow \text{H}_3\text{O}^+ + \text{A}^-$

3. Write the general ionization equation for a base: $\text{B} + \text{H}_2\text{O} \rightarrow \text{BH}^+ + \text{OH}^-$

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Q3. Classify chemicals as acids or bases based on their formulas

Background

Topic: Chemical Classification

This question tests your ability to identify acids and bases from their chemical formulas.

Key Terms:

• Acid: Often contains H at the beginning (e.g., HCl, H2SO4).

• Base: Often contains OH at the end (e.g., NaOH, KOH).

Step-by-Step Guidance

1. Look for formulas with H+ ions (acids) or OH- ions (bases).

2. Apply the Arrhenius definition to classify each formula.

3. Check for exceptions (e.g., NH3 is a base but does not contain OH).

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Q4. Apply the pH scale and calculate pH, pOH, and ion concentrations

Background

Topic: pH and pOH Calculations

This question tests your ability to use the pH scale and related formulas to find concentrations of H3O+ and OH-.

Key Formulas:

• $\text{pH} = -\log[\text{H}_3\text{O}^+]$

• $\text{pOH} = -\log[\text{OH}^-]$

• $\text{pH} + \text{pOH} = 14$

• $[\text{H}_3\text{O}^+][\text{OH}^-] = 1 \times 10^{-14}$

Step-by-Step Guidance

1. Identify the given value (pH, pOH, or ion concentration).

2. Use the appropriate formula to relate pH, pOH, and ion concentrations.

3. For pH, use the inverse log: $[\text{H}_3\text{O}^+] = 10^{-\text{pH}}$

4. For pOH, use the inverse log: $[\text{OH}^-] = 10^{-\text{pOH}}$

5. Check your units (molarity, scientific notation).

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Q5. Explain why the pH of 1.0 M acetic acid is higher than the pH of 1.0 M hydrochloric acid

Background

Topic: Acid Strength and Ionization

This question tests your understanding of strong vs. weak acids and their effect on pH.

Key Terms:

• Strong acid: Completely ionizes in water (e.g., HCl).

• Weak acid: Partially ionizes in water (e.g., acetic acid).

• pH: Lower pH means higher H+ concentration.

Step-by-Step Guidance

1. Recall that strong acids produce more H+ ions than weak acids at the same concentration.

2. Compare the degree of ionization for acetic acid (weak) and hydrochloric acid (strong).

3. Relate the ionization to the resulting pH values.

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Q6. Given an acid in water, write the ionization equation and label the conjugate acid and conjugate base

Background

Topic: Bronsted-Lowry Theory

This question tests your ability to write ionization equations and identify conjugate acid-base pairs.

Key Terms:

• Conjugate acid: Formed when a base gains a proton.

• Conjugate base: Formed when an acid loses a proton.

Step-by-Step Guidance

1. Write the ionization equation for the acid in water: $\text{HA} + \text{H}_2\text{O} \rightarrow \text{H}_3\text{O}^+ + \text{A}^-$

2. Identify the acid (HA), base (H2O), conjugate acid (H3O+), and conjugate base (A-).

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