Question

When a 0.015M aqueous solution of a certain acid is prepared, and the acid is 34% dissociated, calculate the pH of the solution. Round your answer to decimal places.

Options:
a) 1.54
b) 2.23
c) 2.98
d) 3.67

Answer 1

To find the pH of a 0.015M acid solution that is 34% dissociated, multiply the concentration by the percent dissociation to get [H+], then use the pH formula. The final pH, rounded to two decimal places, is closest to 2.23.

Step-by-step explanation:

To calculate the pH of a 0.015M aqueous solution of an acid that is 34% dissociated, we first determine the concentration of hydronium ions ([H+]) that results from the dissociation. The dissociation of the acid can be represented by multiplying the original concentration by the percent dissociation in decimal form:

[H+] = initial concentration × percent dissociation

[H+] = 0.015M × 0.34 = 0.0051M

Now, we use the pH formula:

pH = -log([H+])

pH = -log(0.0051)

To find the pH, we use a calculator to find the log of 0.0051 and then apply the negative sign:

pH = -(-2.29) = 2.29

Hence, the pH of the solution rounds to 2.29, which is closest to option (b) 2.23 when rounded to two decimal places.