Acids and Bases: Step-by-Step Study Guidance (CHMY 121, Chapter 11)

Q1. Select the correct name for each of the following acids:

• HBr

• H2CO3

• HBrO2

Background

Topic: Nomenclature of Acids

This question tests your ability to correctly name acids based on their chemical formulas, using the rules for binary and oxyacids.

Key Terms and Rules:

• Binary acids (H + nonmetal): Use the prefix "hydro-" and the suffix "-ic acid" (e.g., HCl = hydrochloric acid).

• Oxyacids (H + polyatomic ion with oxygen):

  • If the polyatomic ion ends in "-ate", the acid name ends in "-ic acid" (e.g., H2SO4 = sulfuric acid).

  • If the polyatomic ion ends in "-ite", the acid name ends in "-ous acid" (e.g., H2SO3 = sulfurous acid).

Step-by-Step Guidance

1. For HBr, determine if it is a binary acid or an oxyacid by checking if it contains oxygen.

2. For H2CO3, identify the polyatomic ion present and its name.

3. For HBrO2, identify the polyatomic ion (bromite or bromate) and apply the correct naming rule for oxyacids.

4. Match each formula to the correct name using the rules above.

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Q2. Match the formulas of acids and bases with their names:

• HNO2

• Ca(OH)2

• H2SO4

• HIO3

• NaOH

Background

Topic: Acid and Base Nomenclature

This question tests your ability to recognize and name common acids and bases from their chemical formulas.

Key Terms and Formulas:

• Acids: Typically start with H (hydrogen).

• Bases: Typically contain OH (hydroxide) with a metal cation.

• Use the rules for naming acids and bases as described above.

Step-by-Step Guidance

1. Identify which formulas are acids (start with H) and which are bases (contain OH).

2. For each acid, determine if it is a binary acid or an oxyacid and apply the correct naming rule.

3. For each base, name the metal cation followed by "hydroxide".

4. Match each formula to its correct name.

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Q3. Identify each as a characteristic of an acid or a base:

• 1. has a sour taste

• 2. produces -OH in aqueous solution

• 3. has a chalky taste

• 4. is an electrolyte

• 5. produces H+ in aqueous solution

Background

Topic: Properties of Acids and Bases

This question tests your understanding of the physical and chemical properties that distinguish acids from bases.

Key Terms:

• Acid: Substance that produces H+ (or H3O+) in water, tastes sour, can be an electrolyte.

• Base: Substance that produces OH- in water, tastes bitter or chalky, can be an electrolyte.

Step-by-Step Guidance

1. Recall the typical taste and properties of acids and bases.

2. Identify which statements refer to acids and which to bases based on their definitions.

3. Remember that both acids and bases can be electrolytes, but the ions they produce differ.

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Q4. In each of the following equations, identify the Brønsted–Lowry acid and base in the reactants:

Example equation (reformatted):

$\mathrm{HNO_3} (aq) + \mathrm{H_2O} (l) \rightarrow \mathrm{H_3O^+} (aq) + \mathrm{NO_3^-} (aq)$

Background

Topic: Brønsted–Lowry Acids and Bases

This question tests your ability to identify acids and bases according to the Brønsted–Lowry definition (acid = proton donor, base = proton acceptor).

Key Terms:

• Brønsted–Lowry acid: Donates a proton (H+).

• Brønsted–Lowry base: Accepts a proton (H+).

Step-by-Step Guidance

1. Look at the reactants and products to see which species donates an H+ and which accepts it.

2. Identify the acid as the species that loses an H+ and the base as the one that gains an H+.

3. Label each reactant as either the acid or the base.

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Q5. Write the conjugate base for each of the following acids, and the conjugate acid for each of the following bases:

• Acids: HI, H2S, H2CO3

• Bases: NO2-, NH3, OH-

Background

Topic: Conjugate Acid-Base Pairs

This question tests your understanding of how to identify conjugate acids and bases by adding or removing a proton (H+).

Key Terms:

• Conjugate base: What remains after an acid donates a proton.

• Conjugate acid: What forms when a base accepts a proton.

Step-by-Step Guidance

1. For each acid, remove one H+ to write the formula of its conjugate base.

2. For each base, add one H+ to write the formula of its conjugate acid.

3. Be careful with charges when adding or removing protons.

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Q6. Identify the sets that contain acid–base conjugate pairs.

• HNO2, NO2-

• H2CO3, CO3^2-

• HCl, ClO-

• HS-, H2S

• NH4+, NH3

Background

Topic: Conjugate Acid-Base Pairs

This question tests your ability to recognize pairs of species that differ by one proton (H+).

Key Terms:

• Conjugate acid-base pair: Two species that differ by exactly one H+.

Step-by-Step Guidance

1. For each pair, compare the formulas to see if they differ by one H+.

2. If so, they are a conjugate acid-base pair; if not, they are not.

3. Check both the chemical formula and the charge.

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Q7. Identify the conjugate acid–base pairs in the following reaction:

(Reaction not fully provided, but the process is the same for any acid-base reaction.)

Background

Topic: Conjugate Acid-Base Pairs in Reactions

This question tests your ability to identify which reactant and product species are related as conjugate acid-base pairs.

Key Terms:

• Conjugate acid-base pairs differ by one H+.

Step-by-Step Guidance

1. Write out the full balanced equation if not already given.

2. Identify which species on the reactant side donates an H+ and which accepts it.

3. Pair each acid with its conjugate base and each base with its conjugate acid on the product side.

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Q8. Identify each of the following as a strong or weak acid or base:

• HBr

• HNO2

• NaOH

• H2SO4

• Cu(OH)2

Background

Topic: Strength of Acids and Bases

This question tests your knowledge of which common acids and bases are strong (completely ionize in water) or weak (partially ionize).

Key Terms:

• Strong acid/base: Completely ionizes in water.

• Weak acid/base: Partially ionizes in water.

Step-by-Step Guidance

1. Recall the list of common strong acids and bases (e.g., HCl, HBr, H2SO4, NaOH, KOH).

2. Classify each compound as strong or weak based on your knowledge or a reference table.

3. Remember that most acids and bases not on the strong list are considered weak.

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Q9. Using Table 11.3, identify the stronger acid in each pair:

• HNO2 or H2S

• HCO3- or HBr

• H3PO4 or H3O+

Background

Topic: Acid Strength Comparison

This question tests your ability to compare acid strengths using a reference table (such as Table 11.3 in your textbook).

Key Terms:

• Acid strength: Measured by the degree of ionization or the acid dissociation constant (Ka).

Step-by-Step Guidance

1. Refer to Table 11.3 to find the relative strengths or Ka values for each acid.

2. Compare the values for each pair to determine which is stronger.

3. Remember that a higher Ka or more complete ionization means a stronger acid.

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Q10. Write the acid dissociation expression for nitrous acid, HNO2.

Background

Topic: Acid Dissociation (Ka) Expressions

This question tests your ability to write the equilibrium expression for the dissociation of a weak acid in water.

Key Formula:

$\mathrm{HNO_2} (aq) + \mathrm{H_2O} (l) \rightleftharpoons \mathrm{NO_2^-} (aq) + \mathrm{H_3O^+} (aq)$

$K_a = \frac{[\mathrm{NO_2^-}][\mathrm{H_3O^+}]}{[\mathrm{HNO_2}]}$

Step-by-Step Guidance

1. Write the balanced chemical equation for the dissociation of HNO2 in water.

2. Identify the products and reactants in the equilibrium.

3. Write the Ka expression using the concentrations of products over reactants (excluding water).

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Q11. If lemon juice has [H3O+] of 2.0 x 10-3 M, what is the [OH-] of the solution?

Background

Topic: Relationship between [H3O+] and [OH-] in Aqueous Solutions

This question tests your ability to use the ion product constant for water to relate hydronium and hydroxide ion concentrations.

Key Formula:

$K_w = [\mathrm{H_3O^+}][\mathrm{OH^-}] = 1.0 \times 10^{-14}$

Step-by-Step Guidance

1. Write the expression for the ion product constant of water ($K_w$).

2. Plug in the given [H3O+] value.

3. Rearrange the equation to solve for [OH-]: $[\mathrm{OH^-}] = \frac{K_w}{[\mathrm{H_3O^+}]}$

4. Set up the calculation using the provided values.

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Q12. Identify each solution as acidic, basic, or neutral:

• A. HCl with a pH = 1.5

• B. Pancreatic fluid, [H3O+] = 1 x 10-8 M

• C. Sprite soft drink, pH = 3.0

• D. pH = 7.0

• E. [OH-] = 3 x 10-10 M

• F. [H3O+] = 5 x 10-12 M

Background

Topic: pH and Solution Classification

This question tests your ability to classify solutions as acidic, basic, or neutral based on pH or ion concentrations.

Key Terms and Formulas:

• Acidic: pH < 7, [H3O+] > 1 x 10-7 M

• Neutral: pH = 7, [H3O+] = 1 x 10-7 M

• Basic: pH > 7, [H3O+] < 1 x 10-7 M

Step-by-Step Guidance

1. For each solution, compare the pH or ion concentration to the neutral value.

2. Classify as acidic, basic, or neutral based on the comparison.

3. Remember to convert [OH-] to pOH and then to pH if needed.

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Q13. Find the pH of a solution with a [H3O+] of 4.0 x 10-5 M.

Background

Topic: Calculating pH from [H3O+]

This question tests your ability to use the pH formula to calculate the pH from a given hydronium ion concentration.

Key Formula:

$\mathrm{pH} = -\log_{10} [\mathrm{H_3O^+}]$

Step-by-Step Guidance

1. Write the formula for pH in terms of [H3O+].

2. Plug in the given value for [H3O+].

3. Set up the calculation for the logarithm.

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Q14. Determine [H3O+] for a solution that has a pH of 3.42.

Background

Topic: Calculating [H3O+] from pH

This question tests your ability to convert pH back to hydronium ion concentration.

Key Formula:

$[\mathrm{H_3O^+}] = 10^{-\mathrm{pH}}$

Step-by-Step Guidance

1. Write the formula relating [H3O+] and pH.

2. Plug in the given pH value.

3. Set up the calculation for the exponent.

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Q15. Write a balanced equation for the following reaction:

Mg(OH)2 (s) + HBr (aq) → ?

Background

Topic: Acid-Base Neutralization Reactions

This question tests your ability to write and balance a neutralization reaction between a base and an acid.

Key Terms:

• Neutralization: Acid + Base → Salt + Water

Step-by-Step Guidance

1. Write the formulas for the products: the salt (from the cation of the base and the anion of the acid) and water.

2. Balance the equation for both mass and charge.

3. Check that the number of atoms of each element is the same on both sides.

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Q16. Select the correct group of coefficients for each of the following neutralization equations:

Example 1: HCl (aq) + Al(OH)3 (aq) → AlCl3 (aq) + H2O (l)

Example 2: Ba(OH)2 (aq) + H3PO4 (aq) → Ba3(PO4)2 (s) + H2O (l)

Background

Topic: Balancing Neutralization Reactions

This question tests your ability to balance chemical equations, especially for acid-base reactions that form salts and water.

Key Steps:

• Balance the number of each type of atom on both sides of the equation.

• Start by balancing the metal and nonmetal ions, then balance hydrogen and oxygen last.

Step-by-Step Guidance

1. Write the unbalanced equation with all reactants and products.

2. Balance the metal cations and polyatomic ions first.

3. Balance the hydrogen and oxygen atoms by adjusting coefficients.

4. Check your work to ensure all atoms are balanced.

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