Question

A solution is made by dissolving 21.5 g of NaOH in approximately 450 mL of water in a volumetric flask. The solution becomes quite warm, but after it is allowed to return to room temperature, water is added to total 500 mL of solution. Calculate the pH of the final solution. Report pH to 2 decimal places.

Answer 1

The answer to your question is: pH = 13.97

Step-by-step explanation:

Data

NaOH = 21.5 g

Volume = 500 ml

pH = ?

Formula

Molarity = moles / volume (l)

pOH = -log [OH⁺]

pH = 14 - pOH

Moles of NaOH

MM NaOH = 23 + 16 + 1

= 40 g

40 g of NaOH ----------------- 1 mol

21.5 g of NaOH -------------- x

x = 0.538 moles

Molarity = 0.538/ 0.5

= 1.075 M

pOH = -log [1.075]

pOH = 0.0318

pH = 14 - 0.0318

pH = 13.97