Acids and Bases F22

Which of these is a strong acid solution?

• 0.10 M HClO₃(aq)

• 0.10 M HF(aq)

• 0.010 M HBr(aq)

• 0.10 M HNO₂(aq)

• 0.10 M HClO(aq)

Answer explanation

Look at the formula carefully! You must know 7 SA's and recognize these quickly!

Also, M doesn't affect acid strength.

Which solution would have the lowest pH?

• 0.10 M NaOH(aq)

• 0.10 M HCOOH(aq)

• 0.010 M HBr(aq)

• 0.10 M HI(aq)

Answer explanation

Look at both the type of compound (SA, WA, etc.) and its [ ] to predict the answer. No calculation needed!

Which solution would have the highest pH?

• 0.10 M HF(aq)

• 0.10 M NaOH(aq)

• 0.10 M Ba(OH)₂(aq)

• 0.050 M KOH(aq)

Answer explanation

No calculation is needed! Predict the answer from the type of compound and it's [ ].

If a solution has a [H⁺] of 1.0 x 10 ^-5 M, the [OH^-] is ____ and the solution is ______.

• 1.0 x 10 ^-9 M, acidic

• 1.0 x 10 ^-5 M, acidic

• 1.0 x 10 ^-9 M, basic

• 1.0 x 10 ^-5 M, basic

• 9.00, acidic

Answer explanation

If your exponent is wrong, you are not entering exponential notation properly in your calculator.

Compare the 2 [ ]'s to tell if it's more acidic or basic.

What is the pH of a 2.5 x 10^-5 M HBr(aq) solution?

• 4.60

• 5.00

• 2.50

• 9.40

Answer explanation

What type of solution is it? is a K_a value needed?

What is the pH of a 0.010 M Ca(OH)₂ solution?

• 2.00

• 1.70

• 12.30

• 12.00

Answer explanation

What is Ca(OH)₂? [OH-] = ? Should the final pH be high or low?

Which statement(s) are false if two different 0.10 M weak acid solutions are compared? Select all that apply.

• The weaker acid will have a lower pH value.

• The stronger acid will have a larger K_a value.

• The stronger acid will have a higher % ionization.

• The weaker acid is a better proton donor.

Answer explanation

As acid strength increases, which properties are directly related? Inversely?

Use the checkboxes to select all the true statements.

• A strong acid always has a lower pH reading than a weak acid.

• As the concentration of a weak base decreases, pH decreases.

• As the concentration of a weak acid decreases, pH decreases.

• You don’t need a K_a value to calculate the pH for a strong acid.

Answer explanation

Both the type of solution and it's concentration affect the pH of a solution.

For acids, pH decreases as acid strength or [ ] increases.

What is the pH for a 0.25 M HCOOH(aq) (K_a = 1.8 x 10^-4)?

• 0.60

• 2.18

• 4.35

• 11.82

Answer explanation

WA hydrolysis reaction

ICE

K_a = x²/[HA] - x

x = [H₃O⁺]

Calculate the K_b for a weak base solution, B(aq) if the pH = 11.35 for a 0.020 M solution of B(aq).

• 2.5x10^-4

• 1.1x10^-1

• 2.2x10^-3

• 2.8x10^-4

Answer explanation

WB hydrolysis

ICE, where x = [OH^-]

convert pH to pOH to [OH^-]

K_b = x²/[B] - x

* Don't omit x! we know x from pH