Question

ph measures the acidity of a substance, and is described by the equation ph = - log (h+), where h is the concentration of hydrogen ions. human skin has a ph of 5.5. what is its concentration of h+? a 3.16×10 - 6 b 3.16×103 c 1.09×10 - 1 d 2.45×102

Explanation:

Step1: Recall the pH formula

The formula for pH is \(pH =-\log[H^+]\), where \([H^+]\) is the hydrogen - ion concentration. We need to solve for \([H^+]\) given \(pH = 5.5\).

Step2: Rearrange the formula

Starting from \(pH=-\log[H^+]\), we can rewrite it as \(\log[H^+]= - pH\). Substituting \(pH = 5.5\), we get \(\log[H^+]=- 5.5\).

Step3: Convert from logarithmic to exponential form

In exponential form, if \(\log_{10}[H^+]=-5.5\), then \([H^+]=10^{- 5.5}\).
We know that \(10^{-5.5}=\frac{1}{10^{5.5}}\). Also, \(10^{5.5}=10^{5}\times10^{0.5}\), and \(10^{0.5}=\sqrt{10}\approx3.16\). So \(10^{5.5}\approx3.16\times10^{5}\), and \([H^+]=3.16\times10^{-6}\).

Answer:

A. \(3.16\times10^{-6}\)