CHE 105/110 Introduction to Chemistry - Exercises and Answers

1.

Does [H⁺] remain constant in all aqueous solutions? Why or why not?

1.

[H⁺] varies with the amount of acid or base in a solution.

3.

What is the relationship between [H⁺] and K_w? Write a mathematical expression that relates them.

3.

${\text{[H}}^{\text{+}}\text{] =}\frac{K_{\text{w}}}{{\text{[OH}}^{-}\text{]}}$

5.

Write the chemical equation for the autoionization of water and label the conjugate acid-base pairs.

5.

H₂O + H₂O → H₃O⁺ + OH⁻; H₂O/H₃O⁺ and H₂O/OH⁻

7.

For a given aqueous solution, if [H⁺] = 1.0 × 10⁻³ M, what is [OH⁻]?

7.

1.0 × 10⁻¹¹ M

9.

For a given aqueous solution, if [H⁺] = 7.92 × 10⁻⁵ M, what is [OH⁻]?

9.

1.26 × 10⁻¹⁰ M

11.

For a given aqueous solution, if [OH⁻] = 1.0 × 10⁻⁵ M, what is [H⁺]?

11.

1.0 × 10⁻⁹ M

13.

For a given aqueous solution, if [OH⁻] = 3.77 × 10⁻⁴ M, what is [H⁺]?

13.

2.65 × 10⁻¹¹ M

15.

What are [H⁺] and [OH⁻] in a 0.344 M solution of HNO₃?

15.

[H⁺] = 0.344 M; [OH⁻] = 2.91 × 10⁻¹⁴ M

17.

What are [H⁺] and [OH⁻] in a 0.00338 M solution of KOH?

17.

[OH⁻] = 0.00338 M; [H⁺] = 2.96 × 10⁻¹² M

19.

If HNO₂ is dissociated only to an extent of 0.445%, what are [H⁺] and [OH⁻] in a 0.307 M solution of HNO₂?

19.

[H⁺] = 0.00137 M; [OH⁻] = 7.32 × 10⁻¹² M