Question

chemistry 20
final exam 2025
name: ebtesam
acid base

1. if 3.4g of hcl were added to 325ml of distilled water, then the ph of the resulting solution would be

(record your answer in the numerical - response section below)
your answer:

Explanation:

Step1: Calculate the moles of HCl

The molar mass of HCl is \(M = 1 + 35.5=36.5\space g/mol\).
The number of moles of HCl, \(n=\frac{m}{M}\), where \(m = 3.4\space g\). So \(n=\frac{3.4}{36.5}\space mol\approx0.09315\space mol\)

Step2: Calculate the molarity of the HCl solution

The volume of the solution \(V=325\space mL = 0.325\space L\)
The molarity \(C=\frac{n}{V}\), substituting \(n = 0.09315\space mol\) and \(V=0.325\space L\)
\(C=\frac{0.09315}{0.325}\space mol/L\approx0.2866\space mol/L\)

Step3: Calculate the pH

Since HCl is a strong acid, \(HCl
ightarrow H^{+}+Cl^{-}\), and \([H^{+}]=C\) (molarity of HCl)
The formula for pH is \(pH=-\log[H^{+}]\)
Substituting \([H^{+}]= 0.2866\space mol/L\)
\(pH=-\log(0.2866)\approx0.54\)

Answer:

\(0.54\)