Question

The temperature for each solution is carried out at approximately 297 K where Kw=1.00×10−14.
Part A
0.70 g of hydrogen chloride (HCl) is dissolved in water to make 7.5 L of solution. What is the pH of the resulting hydrochloric acid solution?
Express the pH numerically to two decimal places.

Answer 1

First the concentration of HCl should be determined:

[HCl] = (0.70g / 36.46g/mol) / 7.5L = 0.00256 M

HCl is a strong acid and we may assume that it dissociates completely. Therefore,

[H⁺] = 0.00256 M

pH = -log[H⁺] = -log 0.00256 = 2.59

Answer: 2.59