Question

0.50 g of hydrogen chloride (HCl) is dissolved in water to make 4.0 L of solution. What is the pH of the resulting hydrochloric acid solution

Answer 1

Explanation:

Given the mass of HCl is ---- 0.50 g

The volume of solution is --- 4.0 L

To determine the pH of the resulting solution, follow the below-shown procedure:

1. Calculate the number of moles of HCl given by using the formula:

$number of moles of a substance=\frac{given mass of the substance}{its molecular mass}$

2. Calculate the molarity of HCl.

3. Calculate pH of the solution using the formula:

$pH=-log[H^+]$

Since HCl is a strong acid, it undergoes complete ionization when dissolved in water.

$HCl(aq)->H^+(aq)+Cl^-(aq)$

Thus, $[HCl]=[H^+]$

Calculation:

1. Number of moles of HCl given:

$number of moles of a substance=\frac{given mass of the substance}{its molecular mass}\\=0.50g/36.5g/mol\\=0.0137mol$

2. Concentration of HCl:

$Molarity of HCl=\frac{number of moles of HCl}{its molar mass}\\=\frac{0.0137 mol}{4.0 L} \\= 0.003425 M$

3. pH of the solution:

$pH=-log[H^+]\\=-log(0.003425)\\=2.47$

Hence, pH of the given solution is 2.47.