Question

Calculate pH for 2.110 g of LiOH in 230.0 mL of solution. Express your answer using four decimal places.

Answer 1

Molar mass of LiOH,

MM = 1*MM(Li) + 1*MM(O) + 1*MM(H)

= 1*6.968 + 1*16.0 + 1*1.008

= 23.976 g/mol

mass(LiOH)= 2.110 g

use:

number of mol of LiOH,

n = mass of LiOH/molar mass of LiOH

=(2.11 g)/(23.98 g/mol)

= 8.8*10^-2 mol

volume , V = 2.3*10^2 mL

= 0.23 L

use:

Molarity,

M = number of mol / volume in L

= 8.8*10^-2/0.23

= 0.3826 M

This is concentration of LiOH

[OH-] = [LiOH] = 0.3826 M

use:

pOH = -log [OH-]

= -log (0.3826)

= 0.4173

use:

PH = 14 - pOH

= 14 - 0.4173

= 13.5827

Answer: 13.5827