Question

If 1.20 grams of impure solid KHP sample required 2.53 mL of your standardized NaOH to reach the end point, what was the percent KHP in this sample?

mm= 204.2

NaOH M= 0.127 M

Answer 1

NaOH and KHP reacts as:

NaOH(aq) + KHC₈H₄O₄(aq) = NaLiC₈H₄O₄(aq) + H₂O(l)

mol of NaOH reacting = Molarity * volume

= 0.127 M * 2.53 mL

= 0.3213 mmol

= 3.213*10^-4 mol

from above reaction, at equivalence point,

mol of NaOH = mol of KHP

So,

moles of KHP = 3.213*10^-4 mol

molar mass of KHP = 204.2 g/mol

So,

mass of KHP = number of mol * molar mass

= 3.213*10^-4 mol * 204.2 g/mol

= 0.06561 g

mass % of KHP = mass of KHP*100/mass of sample

= 0.06561*100/1.20

= 5.47 %

Answer: 5.47 %