I am doing an elementary experiment regarding separating mixtures. My mixture contained NaCl, SiO2, and CaCO3. In the beginning, I calculated the mass of my mixture (all components together). As I completed the experiment, some of the elements were lost either by partial solubility or improper decantation / filtration techniques. In the end, I calculated each individual mass and found out (without surprise) that it does not equal the mass of the mixture from the beginning of the experiment.

Question

If I were to calculate the % CaCO3 in the mixture, do I divide

mass of CaCO3 / total mass of mixture from the beginning

OR

mass of CaCO3 / the newly calculated total mass obtained from adding what I got for NaCl, SiO2, and CaCO3 throughout the experiment.

Answer 1

% CaCO3 in mixture = [(mass CaCO3 recovered)/(initial mass mixture)]*1-- \ ?

The mass recovered is not the mass you started with.