Question

question 8
the sum of ph and poh in any aqueous solution is equal to:
7
10
14
21
question 9
what does a single unit decrease in ph value indicate about hydrogen (hydronium) ion concentration?
it decreases by 10 times.
it increases by 10 times.
it decreases by 2 times.
it increases by 2 times.

Explanation:

Question 8

In aqueous solutions, the relationship \(pH + pOH=14\) is a fundamental concept in chemistry. This is derived from the ion - product constant of water \(K_w = [H^+][OH^-]=10^{-14}\) at \(25^{\circ}C\). Taking the negative logarithm of both sides: \(-\log(K_w)=-\log([H^+][OH^-])\), and using the property of logarithms \(-\log(ab)=-\log(a)-\log(b)\), we get \(14 = pH + pOH\).

The formula for \(pH\) is \(pH=-\log[H^+]\). Let the initial \(pH = pH_1=-\log[H^+_1]\) and the final \(pH = pH_2 = pH_1 - 1=-\log[H^+_2]\). Then \(-\log[H^+_2]=-\log[H^+_1]- 1\). Rearranging gives \(\log[H^+_2]-\log[H^+_1]=1\). Using the logarithm property \(\log a-\log b=\log\frac{a}{b}\), we have \(\log\frac{[H^+_2]}{[H^+_1]} = 1\). Since \(\log x = 1\) implies \(x = 10\) (because \(\log_{10}x\)), \(\frac{[H^+_2]}{[H^+_1]}=10\), which means the hydrogen (hydronium) ion concentration increases by 10 times.

Answer:

14

Question 9