At a certain elevated temperature, the value of is . Find the exact concentration of ions in neutral — Ionic Equilibrium Chemistry Question
Question
At a certain elevated temperature, the value of $pK_w$ is $13.64$. Find the exact concentration of $H^+$ ions in neutral water at this temperature in $\text{mol L}^{-1}$. If the answer is $a \times 10^{-7}$, enter the exact value of $a$. (Given $\log 1.6 = 0.18$)
💡 Solution & Explanation
In a neutral solution at any temperature, $pH = \frac{pK_w}{2}$. Here, $pH = \frac{13.64}{2} = 6.82$. The hydrogen ion concentration is $[H^+] = 10^{-pH} = 10^{-6.82} \text{ M}$. This can be written as $10^{0.18} \times 10^{-7}$. Since $\log 1.6 = 0.18$, we know that $10^{0.18} = 1.6$. Therefore, $[H^+] = 1.6 \times 10^{-7} \text{ M}$. Thus, $a = 1.6$.