Find the pH of a substance if the hydrogen ion concentration, [tex]H^+[/tex], is [tex]4.23 \times 10^{-6}[/tex] moles per liter. Use the formula [tex]\text{pH} = -\log[H^+][/tex].

A. 5.4
B. 5.6
C. 5.8
D. 6.2

Answer :

To find the pH of a substance when the hydrogen ion concentration (H⁺) is given as 4.23 x 10⁻⁶ moles per liter, we use the formula for pH:

[tex]\[ \text{pH} = -\log_{10}[H^+] \][/tex]

Here's how you solve it step by step:

1. Identify the Hydrogen Ion Concentration:
The hydrogen ion concentration, H⁺, is given as 4.23 x 10⁻⁶ moles per liter.

2. Apply the pH Formula:
Insert the concentration into the pH formula:

[tex]\[ \text{pH} = -\log_{10}(4.23 \times 10^{-6}) \][/tex]

3. Calculate the pH Value:
- First, compute the logarithm base 10 of the concentration: approximately [tex]\(-5.3737\)[/tex].
- Then apply the negative sign to get the pH: [tex]\( 5.3737 \)[/tex].

4. Round to the Nearest Option:
- The pH value calculated is approximately 5.37.
- Comparing with given options, the closest match is 5.4.

Therefore, the pH of the substance is approximately 5.4. So, option A is the correct choice.