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

NameDate

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

A basic solution at 25 °C has [OH⁻] = 0.0001 M. What is its pH, Ari?
A basic solution at 25 °C has [OH⁻] = 0.001 M. What is its pH, Bo?
A basic solution at 25 °C has [OH⁻] = 0.01 M. What is its pH, Esme?
4.
At 25 °C, a solution has pOH 3. What is its pH, Jun?
- 11
- 17
- 3
5.
At 25 °C, what do pH and pOH add up to, Kira?
- 7
- 14
- 10
6.
A solution has [H⁺] = 1 × 10⁻⁵ M. What is its pH, Milo?
- 10
- −5
- 5
7.
A solution has pH 9. What is its [H⁺], Noah?
- 1 × 10⁻⁹ M
- 9 M
- 1 × 10⁹ M
8.
Which [H⁺] is neutral at 25 °C, Pia?
- 1 × 10⁷ M
- 1 × 10⁻⁷ M
- 7 M
9.
Ocean surface water is about pH 8.1. How would you describe it, Tala?
- Slightly acidic
- Strongly basic
- Slightly basic
10.
Ammonia solution is about pH 12.5 and milk of magnesia about 10.5. Which has more OH⁻, Zee?
- Milk of magnesia
- They are equal
- Ammonia solution

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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