How many moles are in 4.64 x 1025 atoms of H2CO3?

Please help! Chemistry is really killing me this unit!

1 Answer
Apr 20, 2018

If I asked you, how many dozen eggs there were in a 144 eggses, would you be able to tell me? The mole is PRECISELY the same sort of collective number as the dozen.

Explanation:

The given question is not sound, in that you SHOULD have asked how many moles there were in 4.64×1025 molecules of carbonic acid (i.e. molecules NOT atoms).

Now we know that a mole of stuff contains 6.022×1023 individual items of that stuff (how do we know, well, your chemistry teacher will try to beat it into your brains, and the number WILL ALWAYS appear as supplementary material in a chemistry exam). And so we take the quotient...

4.64×1025molecules of carbonic acid6.022×1023molecules of carbonic acidmol1=

=77.05molcarbonic acid.

And given that we know that carbonic acid has a molar mass of 62.03gmol1 (and note that you cannot isolate this as a solid)...we gots a mass of...

77.05mol×62.03gmol14779.5g

And back to the number, so-called NA: 6.022×1023 individual hydrogen atoms, 1H, have a MASS of 1g. And thus Avogadro's number is the link between between the micro world of atoms and molecules to the macro world of grams and litres.