Question

question 39
a solution with ph = 5 is _______ than a solution with ph = 7.
10 times more basic
100 times more acidic
2 times more acidic
10 times more acidic

Explanation:

Step1: Recall pH - H⁺ concentration relationship

The pH is defined as $pH = -\log[H^{+}]$. So, for a solution with $pH = 5$, $[H^{+}]_1=10^{- 5}\ M$; for a solution with $pH = 7$, $[H^{+}]_2 = 10^{-7}\ M$.

Step2: Calculate the ratio of hydrogen - ion concentrations

We find the ratio $\frac{[H^{+}]_1}{[H^{+}]_2}=\frac{10^{-5}}{10^{-7}}$. Using the rule of exponents $\frac{a^m}{a^n}=a^{m - n}$, we have $\frac{10^{-5}}{10^{-7}}=10^{-5-( - 7)}=10^{2}=100$. A higher hydrogen - ion concentration means a more acidic solution.

Answer:

B. 100 times more acidic