Author Options:

If one mole of hydrogen is equal to 1.01 grams, then does one mole dihydrogen equal 2.02 grams? Answered



Best Answer 9 years ago

Yes. The definition of a mole is a quantity of material with a mass in grams numerically the same as the atomic or molecular weight. But no one uses "dihydrogen." The term is "molecular hydrogen."

So, I am correct, H2 is equal to 2.02 grams?

Some people use "dihydrogen", "dichlorine" "dinitrogen" etc. It might be archaic, but it happens.

Anyway, wasn't there some move to redefine based on H = 1.00000000? Not sure what's struggling to remember but I thought you would know?


There might have been such a move, but I think you'd find it difficult at best. Mass spectrometers work better with higher A nuclei, and carbon-12 is sufficiently easy to isolate that it's a better candidate for a standard.

No matter which isotope you choose to be the "integer", everything is going to be wonky because of differing binding energies. What's more, if you want a mole of natural hydrogen, it's going to be a mix of 1H and 2H (D) (okay, H2 , D2 , and HD), so the molar mass wouldn't be the isotopic mass anyway.

So, if I were to complete the instructable Hydrogen Generator with a Soda can, what would I get in the end products if i had 1 mole water, (18g) plus 1 mole aluminium, (26.89g) with .02-.05 ml of Galinstan?

Is that natural hydrogen, that is created? Or is it one molecule of O2, and 2 molecules H2 for each molecule of water that is seperated by aluminium?

This is what I was originaly trying to get at, however the most fun part is the journey, now, isn't it? Plus, I received much knowledge towards chemistry. Thanks!


You're not creating anything. Chemical reactions move atoms around from one molecule to another. By "natural", I am pointing out that if you chemically isolate hydrogen from anything, you get a mixture of 1H (a simple proton nucleus) and 2H (deuterium, a proton+neutron nucleus). If you want more info, look it up.

When you split water (by whatever means), it takes 2 molecules of water to make one O2 plus 2 H2 (please use proper notation; it will help you to understand what you read, and help others take you more seriously). Stoichiometry (go look that up) requires that you balance the books on both sides of the reaction.

I dont know how to use subscript in instructables. Please tell? -PKT

Sure! Put a pair of commas before and after what you want to subscript.

Yes, I understand it takes two water molecules. I suppose I did mess up, it's not creating, displacement perhaps? What is happening then? Can you explain the reaction with water and aluminium? -PKT

Right! The aluminum acts as a catalyst. There's a series of reactions that go on, with intermediate states, but when everything is finished the aluminum is left behind. You should look up the exact reactions either in Wikipedia or in a chemistry text at your library.

Hmm, it was defined with hydrogen, but even the C12 definition requires a single isotope.


Wow. You're a lot older than I thought! John Dalton in the 19th Century used hydrogen, but when mass spectrometry was invented, 16O was adopted as the standard.
In 1961, that was switched to 12C for both chemistry and physics.

Iv'e heard the term, "archaic" in many Isaac Asimov novels, definition, please? -PKT

I mean it as an adjective, "characteristic of the past", "antiquated". An online dictionary would give you something similar. L

Then what is equal to 1 mole of H2O? Is it 1 mole dihydrogen (2.02 grams) plus 1 mole of oxygen? Does that equal 1 mole of H2O/Dihydrogen monoxide/water? -PKT

The molecular weight of water (rounded off to integers!) is 2*1 + 16 = 18 amu, so one mole of water masses 18 grams.

So, if I were to complete the instructable Hydrogen Generator with a Soda can, what would I get in the end products if i had 1 mole water, (18g) plus 1 mole aluminium, (26.89g) with .02-.05 ml of Galinstan? -PKT

Notice aluminium in a stable isotope, one of the two, (I think there are only 2.) -PKT


9 years ago

If you're talking about H vs H2, yes. If you meant 'hydrogen' to mean 'hydrogen gas', then it would be the same.

The author must be talking about atomic vs. molecular hydrogen; otherwise the "one mole is equal to 1.01 grams" wouldn't make sense.