Question

1) In saturated limewater, [H+ ]=3.98x10-13 M.

Answer 1

Answer:

1) a) [OH⁻] = 0.025 M.

  b) pH = 12.4.

  c) The solution is basic.

2) a) [OH⁻] = 1.66 x 10⁻⁸ M.

  b) pH = 6.22.

   c) The solution is acidic.

3) a) [H⁺] = 3.16 x 10⁻⁴ M.

   b) pH = 3.5.

    c) The solution is acidic.

4) a) [H⁺] = 3.16 x 10⁻⁷ M.

   b) pH = 6.5.

    c) The solution is acidic.

Explanation:

1) In saturated lime water, [H⁺] = 3.98 x 10⁻¹³ M.

a) Find [OH⁻]

∵ [H⁺][OH⁻] = 10⁻¹⁴.

∴ [OH⁻] = 10⁻¹⁴/[H⁺] = 10⁻¹⁴/(3.98 x 10⁻¹³ M) = 0.025 M.

b) What is the pH?

∵ pH = - log[H⁺].

[H⁺] = 3.98 x 10⁻¹³ M.

∴ pH = - log(3.98 x 10⁻¹³ M) = 12.4.

c) Is the solution acidic, basic, or neutral?

• We can determine the nature of the solution, acidic, basic or neutral, from the value of the pH.

pH is a scale from 0 to 14.

• If pH < 7, the solution is acidic.

• If pH = 7, the solution is neutral.

• If pH > 7, the solution basic.

∵ pH = 12.4 > 7.

∴ The solution is basic.

2) In butter, [H⁺] = 6.0 x 10⁻⁷ M.

a) Find [OH⁻]

∵ [H⁺][OH⁻] = 10⁻¹⁴.

∴ [OH⁻] = 10⁻¹⁴/[H⁺] = 10⁻¹⁴/(6.0 x 10⁻⁷ M) = 1.66 x 10⁻⁸ M.

b) What is the pH?

∵ pH = - log[H⁺].

[H⁺] = 6.0 x 10⁻⁷ M.

∴ pH = - log(6.0 x 10⁻⁷ M) = 6.22.

c) Is the solution acidic, basic, or neutral?

• We can determine the nature of the solution, acidic, basic or neutral, from the value of the pH.

pH is a scale from 0 to 14.

• If pH < 7, the solution is acidic.

• If pH = 7, the solution is neutral.

• If pH > 7, the solution basic.

∵ pH = 6.22 < 7.

∴ The solution is acidic.

3) In peaches, [OH⁻] = 3.16 x 10⁻¹¹ M

a) Find [H⁺]

∵ [H⁺][OH⁻] = 10⁻¹⁴.

∴ [H⁺] = 10⁻¹⁴/[OH⁻] = 10⁻¹⁴/(3.16 x 10⁻¹¹ M) = 3.16 x 10⁻⁴ M.

b) What is the pH?

∵ pH = - log[H⁺].

[H⁺] = 3.16 x 10⁻⁴ M.

∴ pH = - log(3.16 x 10⁻⁴ M) = 3.5.

c) Is the solution acidic, basic, or neutral?

• We can determine the nature of the solution, acidic, basic or neutral, from the value of the pH.

pH is a scale from 0 to 14.

• If pH < 7, the solution is acidic.

• If pH = 7, the solution is neutral.

• If pH > 7, the solution basic.

∵ pH = 3.5 < 7.

∴ The solution is acidic.

4) During the course of the day, human saliva varies between being acidic and basic. If [OH⁻] = 3.16 x 10⁻⁸ M,

a) Find [H⁺]

∵ [H⁺][OH⁻] = 10⁻¹⁴.

∴ [H⁺] = 10⁻¹⁴/[OH⁻] = 10⁻¹⁴/(3.16 x 10⁻⁸ M) = 3.16 x 10⁻⁷ M.

b) What is the pH?

∵ pH = - log[H⁺].

[H⁺] = 3.16 x 10⁻⁷ M.

∴ pH = - log(3.16 x 10⁻⁷ M) = 6.5.

c) Is the solution acidic, basic, or neutral?

• We can determine the nature of the solution, acidic, basic or neutral, from the value of the pH.

pH is a scale from 0 to 14.

• If pH < 7, the solution is acidic.

• If pH = 7, the solution is neutral.

• If pH > 7, the solution basic.

∵ pH = 6.5 < 7.

∴ The solution is acidic.