Mole Baggie Lab

During the Mole Baggie Lab we had to find the identity of two bags filled with different substances. We were given different information about each bag and had to find out more information using balances and proportions. We were also given five possible substances that could be in our bag so we first had to figure out the formulas for each of the substances and their grams per mole so we could match the substance in our bag's grams per mole to one of the possible substances' grams per mole.

My partner and I started by identifying what was in bag B2; the mass of the empty bag [2.57 grams] and the number of representative particles [3.10 x 10^22] were already given to us. We weighed the bag with the substance inside and figured out how much it weighed [5.52 grams], then subtracted the mass of the empty bag from the mass of the full bag to figure out how much the substance weighed [2.95 grams]. Now we knew that the mass of the substance was 2.95 grams but we still did not know what the molar mass was so we set up an equation using Avogadro's number to figure out that it was 0.0514 grams per mole. We then set up another proportion using the mass of the substance and the molar mass to find out how many grams per mole our substance had [2.95/0.0514] which ended up being 57.39 grams per mole. Now that we knew how many grams per mole was in our substance, we just had to match it to one the possible substances that we had to choose from. 57.31 grams per mole is very similar to 58.44 grams per mole, so we said that bag label B2 was Sodium chloride [NaCl].

After we figured out what was in bag B2, we had to figure out what was in bag A5; the mass of the empty bag [2.56 grams] and the molar mass [0.025 grams per mole] were given to us. We weighed the bag with the substance inside to figure out how much the full bag weighed, [4.71 grams] then subtracted the mass of the empty bag from the mass of the full bag to figure out how much the substance weighed [2.15 grams]. Now that we knew the mass of the substance and the molar mass, we just set up a proportion to figure out how many grams per mole there was in the substance, [2.15/ 0.025] which ended up being exactly 86 grams per mole. Now that we knew how many grams per mole was in our substance, we just had to match it to one of the possible substances we had to choose from. 86 grams per mole is similar to 81.41 grams per mole, so we said that bag A5 was Zinc oxide [ZnO].

Bag B2 was Sodium Chloride [NaCl].
Bag A5 was Zinc Oxide [ZnO].

Here is picture of our calculations: