Mass of beaker (g) = 51.169

Mass of beaker plus copper oxide (g) = 51.349

Mass of copper oxide (g) = .180

Mass of beaker plus copper (g) = 51.261

Mass of copper obtained (g) = .092

Mass of oxygen in the copper oxide (g) = .088

Questions:

1) Calculate the observed percentage composition of your copper oxide. Show your calculations. From this result, deduce which pure oxide you were given.

2) Do the observations you have reported, and the properties you looked up in the pre-lab questions, support your calculated result? Explain.

3)Calculate how many milliliters of 6M Hydrochloric acid were actually required to react with your sample of copper oxide (show your calculation). approximately what percentage excess did you use.

4) Calculate the observed empirical formula of your copper oxide, i.e., the formula based exactly on your experimental results.