Question:medium

The pH of a sample of vinegar is 3.76. Calculate the concentration of hydrogen ion in it in \(\text{mol dm}^{-3}\) ?

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Split powers: \(10^{-3.76} = 10^{-4} \times 10^{0.24}\) for faster calculation.
Updated On: May 14, 2026
  • \(1.97 \times 10^{-4}\)
  • \(1.738 \times 10^{-4}\)
  • \(1.84 \times 10^{-4}\)
  • \(1.283 \times 10^{-4}\)
Show Solution

The Correct Option is B

Solution and Explanation

Step 1: Understanding the Concept:
The pH of a solution is defined as the negative base-10 logarithm of its hydrogen ion concentration \([\text{H}^+]\). Conversely, the \([\text{H}^+]\) can be found by taking the antilogarithm of the negative pH.
Step 2: Key Formula or Approach:
\[ \text{pH} = -\log_{10}[\text{H}^+] \] \[ [\text{H}^+] = 10^{-\text{pH}} \] Step 3: Detailed Explanation:
Given \(\text{pH} = 3.76\).
\[ [\text{H}^+] = 10^{-3.76} \] To calculate this without a calculator, we write: \[ [\text{H}^+] = 10^{(0.24 - 4)} = 10^{0.24} \times 10^{-4} \] The antilog of $0.24$ is approximately $1.738$.
Thus, \([\text{H}^+] = 1.738 \times 10^{-4}\text{ moldm}^{-3}\).
Comparing with options, this matches option B.
Step 4: Final Answer:
The concentration is \(1.738 \times 10^{-4}\text{ moldm}^{-3}\).
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