Post Laboratory?

Question

If the outside of a test tube is not dried after vaporizing the liquid, will the molar mass of the compound be too high or too low?

Answer 1

The molar mass of the compound is a constant number, calculated by determining the number of each element in the compound and using the periodic table, adding the atomic mass of each element.

However, if you are asking if excess liquid on the outside of the test tube will affect your end yield, then yes, it will. Ideally, you would have found the mass of the tube before the experiment, done the experiment, and then weighed the tube with your end product....subtract the tube mass from the total mass of tube and product, you have a mass of product.

Extra liquid on the outside of the tube can be considered a source of error because it will contribute to the total mass of tube and compound.

Answer 2

I presume that you are weighing before and after the vaporizing of the liquid.

Now if you do not dry the tube, whereas it was before the experiment weigh in, then the difference will be less than what it should be. Thus, you will get an underestimate for the final answer.

Answer 3

You are measuring the molar mass of the compound, not the liquid outside the test-tube. It doesn't affect the molar mass.