Question

A solution of naoh(aq) contains 11.6 grams of naoh in 129 ml of solution. calculate the ph at 25◦c.

Answer 1

First, we need to determine the number of moles of NaOH:

n(NaOH) = m/M = 11.6/40 = 0.29 mole

Then, the concentration of NaOH solution can be calculated:

c(NaOH) = n/V = 0.29/0.129 = 2.25 mol/L

The concentrations of NaOH and OH⁻ ions are equal, so we can determine pOH:

pOH = -log[OH⁻] = -log2.25 = -0.35

Finally, pH value is:

pH + pOH = 14

pH = 14 - (-0.35) = 14.35