Question

Calculate the volume of a standard solution needed to reach the end point.

-Calculate the molarity of 25.0mL of an HCl solution titrated with 0.16M NaOH solution. The end Point was reached when 24.3mL of the standard solution was added.

-Calculate the molarity of a standard solution of KOH if 18.0mL of the solution was needed to titrate 0.919g of KHP.

Answer 1

1) NaOH + HCl ------> NaCl + H2O

this reaction is 1:1 reaction

V1 × M1 = V2 × M2

V1 = volume of HCl, 25ml

M1 = molarity of HCl, ?

V2 = Volume of NaOH, 24.3ml

M2 = Molarity of NaOH , 0.16M

M1 = V2 × M2/V1

= 24.3ml × 0.16M / 25ml

= 0.1555M

So, molarity of HCl = 0.1555M

2)   Mass of KHP = 0.919g

molar mass of KHP = 204.22g/mol

no of mole of KHP = 0.919g/204.22g/mol = 0.0045

KHP + KOH --------> K2P + H2O

1:1 molar reaction

Therefore,

0.0045mol of KHP react with 0.0045mol of KOH

No of mole of KOH present in 18ml = 0.0045mol

Molarity of KOH = (0.0045mol/18ml)×1000ml = 0.25M