If each beaker contains exactly one mole of a substance, why are the volumes not the same?

Question

If each beaker contains exactly one mole of a substance, why are the volumes not the same?

Answer 1

First you must realize that a mole is just a number. it is not a measurement of volume, like a liter, or a measurement of weight like a kilogram. to say a mole of something is like saying a dozen of something (except A LOT MORE). So if I said to you that one cup contains a dozen marbles and another contains a dozen rocks, the rocks would occupy a greater volume even though they have the same number. the only difference in your case is that instead of rocks and marbles, you have water molecules and polycarbonate molecules, and instead of a dozen of each you have 6.02 x 10^23 of each.

Answer 2

the atoms of each molecule are different sizes. One mole just means that the beaker contains 6 x 10^23 molecules

Answer 3

At STP the volumes of a mole of different gases would be equal, but this is not true for liquids and solids.

Answer 4

You do have the same number of substances (6.022*10^23)

Let's say that you have water, and you have glucose in separate beakers.

Water is composed of 3 atoms put together (H2O) while glucose is put 24 atoms (C6H12O6). So the very size of the two differ. Which means that you should have a larger volume of glucose than water. The size on a molecular scale does matter.

Answer 5

Density: number of grams/ml

Atomic (or molecular) weight

volume = 1 mole * at (or molecular) wt (g/mole)/ (g/ml)

Unless the two beakers contain the same material, density and at (or molecular) wt differ