Formula of a Hydrate Lab

On Monday, we had our pre-lab quiz for the copper sulfate hyrdate lab. To my relief, my partner and I both passed! I had been stressing over it for the entire day, so I was very glad to have passed. We first took the mass of the test tube and then the mass of the test tube and the copper sulfate. Next, we used the bunsen burner to heat the substance until it turned white, indicating that it had changed into an anhydrous salt. Apparently, we were supposed to take the exact number that was shown on the scale, but instead, we rounded the mass numbers to the nearest thousandths as that was what was on the lab paper. This led to a large percentage of error when we calculated for "n" of the hydrate based on our mass numbers. It was actually 14%! We went back and tried to recall the exact numbers that were on the scale. We also had to reweigh some of the items to get the accurate mass reading. When we re-calculated for "n" with our more accurate mass numbers, we still got about 14% error. Our last option was to heat the substance some more, making it much more whiter. This led to a decrease in the mass of the test tube plus the anhydrous salt. With THIS new mass number, "n" was much closer to the needed value of 5, giving us only a 1% error!

Final thoughts on the lab: I believed it was a pretty interesting lab; It was super cool to watch the blue gradually turn into white as the water evaporated. Hopefully, next time we will remember to use the whole mass reading on the scales to prevent errors.