Question

How do I find the mass of KHP?
0.5050 grams of KHP was used and placed into a 250mL volumetric flask and diluted to the mark with distilled water. 50.00mL of this KHP solution was placed in a 250mL beaker. It took 14.75mL of 0.0067M of NaOH to reach the endpoint. What is the mass of the sample? What is the wt%?

Answer 1

You have the mass of the KHP sample. You weighed out 0.5050 g (of course you've diluted it; perhaps that is the question; i.e., what is the mass of the KHP in the titrated sample? :-).

How many moles NaOH did you use? M x L = moles = 0.0067M x 0.01475 = 9.88E-5 moles
NaOH. Since KHP has one H and NaOH has 1 OH, moles NaOH = moles KHP; therefore, moles KHP = 9.88E-5.
grams KHP = 9.88E-5 moles x molar mass KHP = ? grams KHP in the titrated sample. Convert that to grams in the original sample. That will be
?g titrated sample x (250/50) = x grams KHP in the original 0.5050 g sample.
%mass KHP = (x g in sample/0.5050)*100 = ??
Most don't work the problem as I did. Most do it this way.
mass KHP in the titrated sample = 0.5050 x (50/250) = 0.1010 g.
%KHP = (g titrated/0.1010)*100 =