Question

question 11
the ph of lemon juice is approximately 2.40. at this ph, the proton concentration h+ is?

Explanation:

Step1: Recall the formula for pH

The formula for pH is \(pH = -\log[H^{+}]\). We need to solve for \([H^{+}]\).

Step2: Rearrange the formula

From \(pH = -\log[H^{+}]\), we can rewrite it as \(\log[H^{+}]=-pH\). Then, using the definition of a logarithm (\(y = \log_{10}x\) implies \(x = 10^{y}\)), we have \([H^{+}]=10^{-pH}\).

Step3: Substitute the given pH value

Given \(pH = 2.40\), substitute into the formula: \([H^{+}]=10^{- 2.40}\).
We know that \(10^{-2.40}=10^{-(2 + 0.40)}=10^{-2}\times10^{-0.40}\).
Since \(10^{-0.40}\approx0.40\) (because \(10^{0.4}\approx2.5\), so \(10^{-0.4}=\frac{1}{10^{0.4}}\approx0.4\)), then \(10^{-2}\times10^{-0.40}\approx0.40\times10^{-2}=4.0\times 10^{-3}\space M\).

Answer:

\(4.0\times 10^{-3}\space M\)