00:01
Problem 15 asks you to state and then explain the law of definite proportions.
00:06
So this law of definite proportions proposed by proust says that all samples of a given substance have the same proportion of component particles.
00:36
And so what this means is, for instance, if you take two sources of water, as long as it's pure water, there will always be two hydrogen atoms for every one.
00:50
One oxygen atom.
00:52
Now if we extend this as your book does to the masses of these component particles, the mass of hydrogen per mole is one gram, the mass of oxygen per mole is 16 grams, and so two times one is two, and then the mass of oxygen being 16 is 16 or 1 to 8 mass ratio.
01:18
So whether you're looking at the component atoms of a given substance or the mass ratio of those atoms, it will always be constant for any sample of that particular substance.
01:34
And this ratio is really important because any other ratio of atoms gives you a completely different substance...