Question

a solution has a hydrogen ion concentration of $1 \times 10^{-12}$m. what is its ph?

1. -12
2. +12
3. +0.12
4. -0.12

Explanation:

Step1: Recall pH formula

The formula for pH is \( \text{pH} = -\log_{10} [\text{H}^+] \), where \( [\text{H}^+] \) is the hydrogen ion concentration.

Step2: Substitute the given concentration

Given \( [\text{H}^+] = 1 \times 10^{-12} \, \text{M} \). Substitute into the formula:
\( \text{pH} = -\log_{10} (1 \times 10^{-12}) \).

Step3: Simplify the logarithm

Using the logarithm property \( \log_{10}(a \times 10^b) = \log_{10}a + b \), here \( a = 1 \), so \( \log_{10}(1 \times 10^{-12}) = \log_{10}1 + (-12) = 0 - 12 = -12 \). Then \( \text{pH} = -(-12) = 12 \).

Answer:

1. +12