I've still got a few queries with the preliminary course (1 Viewer)

[Lobster]

Yes its official, i suck at chem

I'm rereading the preliminary course and i still have a bit of trouble with mole theory

basicially i understand all of it except i dont know how to find out the mass of 1 atom of zinc - i've been stuck on this for ages and its pretty embarassing as im sure most will know how to do it.

Is there an equation for figuring this out? I read through CC and i simply cant find it


I also have a few problems with the HSC course and right now im trying to learn it as well as study for other subjects. Is there someone who is willing to help me by answering questions as i post them?

Cheers

 

[Lobster]

also theres another question i just cant get

N and H form to make NH3 how many moles of hydrogen would it take to form 40 moles of ammonium NH3

i got 120 by multiplying 40 by 3 but i know its wrong because i looked at the answers

what the hell do i do????

 

[BlackJack]

Mass of 1 single atom of zinc???
it's very light... divide the molar mass of zinc by avogadro's number. That's te mass for 1 atom.

Hyddrogen is always H2, so when you did 120 moles it is 120 moles of H. The answer should be 60 moles.

 

[McLake]

Originally posted by Lobster
also theres another question i just cant get

N and H form to make NH3 how many moles of hydrogen would it take to form 40 moles of ammonium NH3

i got 120 by multiplying 40 by 3 but i know its wrong because i looked at the answers

what the hell do i do????

N2 + 3H2 = 2NH3

so 40M of ammonium needs 40*(3/2) = 60M Hydrogen

Edit: Sorry, BlackJack already had the answer (that's what I get for sitting next to him in class ...)

 

[Lobster]

Thanks a lot guys.

So for the first one I take the molar mass of zinc which if i am correct is equivalent to the atomic weight which is 65.4 and divide it by avagadros number which is 6.02 x 1023

that gives me 1.09 x 1022 and that sounds right

its a real help to finally understand some of the things that you didn't know until now so again thanks