# What is the PH of 0.001 moldm-3 solution of sodium hydroxide?

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QuizTablet Community! A. 14

B. 13

C. 12

D. 11

D

## SOLUTION…

For sodium hydroxide, its concentration of 0.001 moldm-3 is for hydroxide ion (and not hydrogen ion), this means:

P(OH) = -Log[OH]

P(OH) = -Log[0.001]

P(OH) = -Log[10^-3]

P(OH) = -Log^-3

P(OH) = -(-3) = 3

But we know that P(H) + P(OH) = 14,

Therefore, P(H) = 14 – P(OH) = 14 – 3 = 11

### Now for the right answer to the above question:

1. Option A is incorrect.
2. Option B is incorrect.
3. C is incorrect.
4. D is the correct answer.

## QUICK TIPS…

• If the concentration of an acid is given, then this concentration is for hydrogen ion, and P(H) = -Log [H].
• If the concentration of a base is given, then this concentration is for hydroxide ion, and P(OH) = -Log [OH].
• And PH + POH = 14.
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Use the questions and answers session to deal further on this topic…

/ culled from 2018 JAMB-UTME Chemistry question 33 /

##### What is the PH of 0.001 moldm-3 solution of sodium hydroxide? » QuizTablet 