A KPH acid solution is made by dissolving 0.505 g of KPH (MW=204.22 g/mol) in 25
ID: 1042720 • Letter: A
Question
A KPH acid solution is made by dissolving 0.505 g of KPH (MW=204.22 g/mol) in 25.00 ml of water. This acid solution was used to standardize a NaOH solution of unknown molarity. The titration of the 25.00 ml of KPH acid solution with the base required 30.71 ml of NaOH solution to reach the neutralization endpoint. What is the molar concentration of the NaOH solution? A KPH acid solution is made by dissolving 0.505 g of KPH (MW=204.22 g/mol) in 25.00 ml of water. This acid solution was used to standardize a NaOH solution of unknown molarity. The titration of the 25.00 ml of KPH acid solution with the base required 30.71 ml of NaOH solution to reach the neutralization endpoint. What is the molar concentration of the NaOH solution?Explanation / Answer
Neutralisation reaction is,
KPH (aq.) + NaOH (aq.) -----------> KNaP (aq.) + H2O (l)
Mass of KHP = 0.505 g.
Molar mass of KHP = 204.22 g/mol
Moles of KHP = mass / molar mass = 0.505 / 204.22 = 0.00247 mol
Molarity of KHP = moles / volume of soluion in L = 0.00247 / 0.02500 = 0.0989 M
Using neutralisation formula,
M1 * V1 = M2 * V2
0.0989 * 25.00 = M2 * 30.71
M2 = molar concentration of NaOH = 0.0805 M