Question

A mixture containing ammonium chloride, sodium chloride and sand will be analyzed. The mass of the mixture was found and then transferred to an evaporating dish. Directions were misread and water was added to the mixture in the evaporating dish before it was heated. Give two different procedures that would allow the determination of the mass percentage of each component in the mixture. Obtaining a new sample is not an option.

Answer 1

If water was added to the mixture. One method of mass percentage estimation would be to first filter the liquid which will have NH4Cl and NaCl in it and leave sand away. Weigh the sand left for mass percentage determination of sand present. Heat the remaining solution to evaporate NH3. Mass balance left should give the amount of NH4Cl mass percentage in total mixture. The remaining solution should be concentrated to recover NaCl from it and use for mass percentage determination.

Another method would be To first heat the solution to remove NH3 and weigh the remaining solution. The balance should be NH4Cl mass present in mixture. Filter the remaining solution to get sand out and concentrate the left out solution to recover NaCl. All three masses are then used for mass percentage determination.