Answer to Question #24040 in Chemistry for arcdp

Question

1) 4g of NaOH is mixed with 1.5L of a solution which has a pH of 1.54, what is the new pH?
2) A solution of 4ml of LiOH of 0.5M and 15ml of 0.1M of H are mixed, what is the new pH?
Pls. answer in complete, your answer is very helpful to me tnx...

Answer 1

1)
A pH of 1.54 means [H⁺] is 10^-1.54 or 0.029 M

4 g of NaOH in 1.5 L of water is a concentration of 0.067 M

The OH^- and H⁺ will react, leaving 0.038 M OH^-

Using K_w, that gives 2.6 x 10^-13 for the concentration of H⁺, which is a pH 12.6

2)
4 mL of 0.5 M OH^- contains 2 mmol of OH^-

10 mL of 0.1 M H⁺ contains 1 mmol of H⁺

After they react, you'll have 1 mmol of OH^- left in a total of 19 mL, or a 0.053 M solution

That means 1.9 x 10^-13 M H⁺, or a pH of 12.7