I got another sleepless night with one of your homework questions. The problem is No. 3. I can easily imagine to make pure hydrogen

and oxygen from water using an electric device. The ratio of the masses of these two elements is probably 1 to 8. Then how I can prove the proportion of atoms in a water molecule 2H and one O?

I have read up to chapter 3 of the text and reviewed the lecture note,

but I have no clue. Please give us a hint in the class on Tuesday.

Sleepless in Baton Rouge

Sorry, I can't do it in lecture. Too much else to do. From a hydrolysis experiment on hydrogen peroxide you will generate equal parts of oxygen and hydrogen. This proves that water is not HO (as Dalton thought) but it doesn't prove that hydrogen peroxide is the all-important 1:1 compound of H and O. It is the inability to make H and O compounds with less than one part hydrogen to sixteen parts oxygen (by weight) that suggests that hydrogen peroxide is a 1:1 compound (later, we can discover it is a 2:2 molecule).

Failure is important in science. Our belief that hydrogen is the lightest element evolved precisely because we could find no lighter elements. All the other "laws" are similar: no one has seen energy get "lost" or "gained" but many have tried.

Paul Russo