Grade 10 · Science · Chemistry

10th grade The pH scale and pH calculations worksheet

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The pH scale and pH calculations

Grade 10 Science Worksheet - Challenge Me

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Circle the best answer, or write your answer on the line.

In 0.10 M acetic acid, [H⁺] = 0.0013 M. Using pH = −log[H⁺], what is the pH to two decimal places, Ari?
In 0.010 M acetic acid, [H⁺] = 0.00042 M. Using pH = −log[H⁺], what is the pH to two decimal places, Bo?
In 1.0 M acetic acid, [H⁺] = 0.0042 M. Using pH = −log[H⁺], what is the pH to two decimal places, Esme?
4.
A solution has pH 3.0. What is its [H⁺], Jun?
- 0.003 M
- 3 M
- 0.001 M
5.
0.10 M HCl has pH 1.0 but 0.10 M acetic acid has pH 2.89. Why, Luz?
- Acetic acid ionizes partly
- The HCl solution is more dilute
- Acetic acid has more H⁺
6.
Milo says pH 2 is twice as acidic as pH 4 because 4 is double 2. Agree or disagree?
- Disagree: it has 100 times more H⁺
- Agree: 4 is exactly twice as big as 2
- Agree: lower pH is less acidic
7.
Noah says going from pH 7 to pH 4 makes [H⁺] three times bigger. Agree or disagree?
- Disagree: it is 1,000 times bigger
- Agree: [H⁺] falls as pH falls
- Agree: the pH fell by exactly three
8.
Pia says a basic solution has no H⁺ ions at all. Agree or disagree?
- Disagree: it has fewer H⁺ than OH⁻
- Agree: H⁺ ions belong to acids alone
- Agree: bases contain no hydrogen
9.
1.0 M NaOH has pH 14.0 at 25 °C. What is its pOH, Tala?
- 14.0
- 7.0
- 0.0
10.
Pure water at 25 °C has equal [H⁺] and [OH⁻]. What is each, Zee?
- 1 × 10⁻¹⁴ M
- 7 M
- 1 × 10⁻⁷ M

The pH scale and pH calculations. Every version has 10 questions, and the answer key prints on the second page.

I can find pH from [H⁺] with pH = −log[H⁺], starting with exact powers of ten.
I can say that each pH step is ten times the H⁺, and that at 25 °C 7 is neutral and pH + pOH = 14.
I can go from [OH⁻] to pOH to pH, and from pH back to [H⁺].
I can place household liquids on the strip and compare them.

Standard: none (TX, FL)

pH: −log[H⁺]; lower means more acidic

pOH: −log[OH⁻]

neutral: Equal H⁺ and OH⁻; pH 7 at 25 °C

Kw: [H⁺] × [OH⁻] = 1.0 × 10⁻¹⁴ at 25 °C

logarithm: The power of ten a number equals

Your child dropped the minus sign in pH = −log[H⁺]. The log of a small number is negative, so the minus makes pH positive.

Your child gave the pOH. From [OH⁻] you get pOH first; then pH = 14 − pOH at 25 °C.

Your child counted decimal places and rounded up. pH is −log[H⁺], which lands between whole numbers here.

What is the most common mistake with the ph scale and ph calculations?

Your child dropped the minus sign in pH = −log[H⁺]. The log of a small number is negative, so the minus makes pH positive.

Are these 10th grade science worksheets free to print?

Yes. All 6 printable versions at each level are free to print, with the answer key, and no account is needed.

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