posted by BEE on .
A student actually used 0.847g sample of impure KHP and the endpoint was reached after 19.82 ml of sodium hydroxide solution was added, What is the percent KHP in the unknown to four significant figures.
The equation is KHP + NaOH ==> H2O + KNaP
moles NaOH = M x L = ??
Convert moles NaOH to moles KHP. That is 1:1 ratio (from the coefficients in the balanced equation) so moles KHP = moles NaOH.
grams KHP = moles KHP x molar mass KHP
%KHP = (grams KHP/0.847)*100 = ??
Note: Your post has only three significant figures in the 0.847 g sample; therefore, you cannot give an answer to four s.f. (unless of course that was 0.8470). A second note, and more troubling, is that you provided no molarity for the NaOH. Without that you can't work the problem anyway.
I don't agree this answer. number %khp so high