Question

the ph of a solution is measured as 4.5. what is the hydrogen ion concentration of the solution?

a. 3.2 × 10⁻⁵ m

b. 4.0 × 10⁻⁵ m

c. 3.2 × 10⁴ m

d. 4.5 m

Explanation:

Step1: Recall pH formula

The formula relating pH and hydrogen ion concentration $[H^+]$ is $pH = -\log_{10}[H^+]$. We need to solve for $[H^+]$, so we can rearrange the formula to $[H^+] = 10^{-pH}$.

Step2: Substitute pH value

Given $pH = 4.5$, substitute into the formula: $[H^+] = 10^{-4.5}$.

Step3: Calculate $10^{-4.5}$

We know that $10^{-4.5}=10^{-4 - 0.5}=10^{-4}\times10^{-0.5}$. Since $10^{-0.5}=\frac{1}{\sqrt{10}}\approx0.316$, then $10^{-4}\times0.316 = 3.16\times 10^{-5}\approx3.2\times 10^{-5}\ M$.

Answer:

A. $3.2\times 10^{-5}\ M$