Question

A sample of fruit juice is found to have a hydrogen ion concentration of 2.87 x 10-4. What would the pH be?

Answer 1

To calculate the pH from the hydrogen ion concentration \([H^+]\), you can use the formula:

\[
\text{pH} = -\log[H^+]
\]

Given the hydrogen ion concentration is \(2.87 \times 10^{-4}\), you can substitute this value into the formula:

\[
\text{pH} = -\log(2.87 \times 10^{-4})
\]

Now, calculate the logarithm:

1. Find the logarithm of \(2.87 \times 10^{-4}\):
\[
\log(2.87 \times 10^{-4}) = \log(2.87) + \log(10^{-4}) = \log(2.87) - 4
\]

Using a calculator, \(\log(2.87) \approx 0.457\).

2. Therefore,
\[
\log(2.87 \times 10^{-4}) \approx 0.457 - 4 = -3.543
\]

3. Now, take the negative:
\[
\text{pH} = -(-3.543) = 3.543
\]

So, the pH of the fruit juice is approximately **3.54**.