Despite the superior intellect of our lab workers, none of the problems above actually caused the discrepancies. This occurs sometimes with unexpected or unexplained results, where multiple hypotheses can explain the cause of the discrepancy occur. Here is a challenge: closely examine each video, and see if you are more observant than our lab workers by determining the actual source of the error.

Haven't evaporated all of the water

Explanation:

One of the main sources of error that occur in a formula of a hydrate lab is that all of the water is not evaporated. We can see at the end of the video that half of the CoCl2 is a light blue colors and the other half is a dark blue color. This indicates that all of the water still has not been evaporated off, resulting in the actual mass of the salt to be greater than the predicted value.

i just learnt this recently but i need to look through my notes again

it is the most commonly accepted one