Answer to Question #127631 in General Chemistry for Gabriela

Question

125ml of 1.00M HCl is added to 100ml of 1.00M NaOH. What is the pH of the resulting solution?

Answer 1

NaOH + HCl --> NaCl + H₂O

Moles HCl: 1.00M x 0.125L = 0.125 mol

Moles NaOH: 1.00M x 0.1L = 0.1 mol - limiting reactant because the mole ratio according to the equation is 1 : 1.

Moles of HCl remaining after the reaction: 0.125 - 0.1 = 0.025 mol

The total volume of the mixture: 125 + 100 = 225 mL = 0.225 L.

Assuming the complete dissociation of HCl:

[H⁺] = 0.025mol / 0.225L = 0.11 M

pH = -log[H⁺] = 0.96

Answer: 0.96