Chem Class- January 28, 2010

Today we started a lab that involved testing the stoichiometric method. We are to check to see if the mass of the precipitate matches with our prediction.

According to our prediction, 1.74 g of SrSo4 (Strontium sulphate) should be produced.

2.00 g Sr(NO3)2 x 1 mol SrSO4/1 mol Sr (NO3)2 x 183.7 g SrSO4/ 1 mol = 1.74 g SrSO4

Basically, in the experiment, 2.00 g of Strontium nitrate is dissolved in 50 mL of water and then reacted with excess Copper (II) Sulphate (3.00 g). The product (Strontium sulphate and copper (II) Nitrate) is a precipitate. After mixing the solutions, the precipitate will be separated by filtration, dried and then weighed. The last thing we did so far was place the filter paper in the drying oven. Next class, we are to record the mass of precipitate and filter paper along with a number of other observations: Mass of copper (II) Sulphate used, mass of Strontium Nitrate used and mass of precipitate

As part of our Analysis and Conclusion, we are to calculate the number of moles of precipitate that were formed as well as the percent error for our results. While doing the lab, we needed to make sure not to leave any of the precipitate behind after pouring the mixture into a funnel. This could greatly affect our results. While carrying out the procedure of the lab, we wore our lab aprons and lab goggles. Remember, safety first!

The balanced chemical equation for the lab:

Sr(NO3)2 + CuSO4 -----> SrSO4 + CU(NO3)2

Strontium Nitrate

Copper (II) Sulphate