Answer to Question #135971 in General Chemistry for Dalia

Question

1. Calculate the mass of KHP (KHC₈H₄O₄) needed to react completely with 25.00 mL of a 0.1 M NaOH solution. Consider the reaction equation to be as shown below. HP^– (aq) + OH^– (aq) → H₂O(l) + P^2– (aq)

Answer 1

molar mass of KHP = [1*12.01 + 5*1.01+ 1*39.10 + 4*16]g/mol

 =204.22 g/mol

Given

molarity of NaOH = 0.1 M

volume of NaOH = 25 ml = 0.025 L

mols of NaOH reacted = volume * molarity = 0.025 L * 0.1 M = 0.0025 mols

HP^– (aq) + OH^– (aq) → H₂O(l) + P^2– (aq)

So mols of KHP present = 0.0025 mol ,because from above equation it is clear that

KHP and NaOH are in 1:1 mole ratio.

mass of KHP needed = mols * molar mass

= 204.22 g/mol * 0.0025 mols =0.51055 g

ANSWER:

mass of KHP needed =0.5 g