Question

A student cleaned a crucible with HCl. After pouring the HCl into the waste container, the crucible was neither rinsed with water or dried before the student added the NaHCO3 and KCl mixture. The crucible contained some residual HCl. How would this experimental error affect the calculated percentage of NaHCO3 in the mixture? Justify answer with explanation. (Hint: NaHCO3 is a base.)

Answer 1

You didn't furnish enough information to answer; i.e., I don't know what you're determining. If NaHCO3, then be aware that HCl and NaHCO3 react as follows:
NaHCO3 + HCl ==> H2O + CO2 + NaCl./

Therefore, some of the NaHCO3 added in the NaHCO3/KCl mixture will not be there. You can take it from here.