# A level Chemistry help!

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#1
hey,
can anyone help me on this
How many molecules are in 30.0 moles of ammonia, NH3 molecules?
do I just x by avagadros constant
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3 years ago
#2
Yup that's exactly what you do! As avagadro's constant is the number of particles in a mole and thus to find out amount of particles is x amount of moles you multiply by avagadro's constant. Hope it helps!
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#3
(Original post by ronalda04)
Yup that's exactly what you do!
dont I need to x by 2 because there are 2 molecules ( nitrogen and hydrogen)
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3 years ago
#4
(Original post by mynameisno123)
dont I need to x by 2 because there are 2 molecules ( nitrogen and hydrogen)
no no no. NH3 is one whole molecule, you don't do it for the seperate elements in the molecule
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#5
(Original post by Kaneki Amano)
no no no. NH3 is one whole molecule, you don't do it for the seperate elements in the molecule
so what if it asks me for atoms?
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3 years ago
#6
(Original post by mynameisno123)
dont I need to x by 2 because there are 2 molecules ( nitrogen and hydrogen)
No you don't as a mole is avagadro's constant amount of particles; which can be either molecules (NH3) or atoms (N or H)
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#7
(Original post by ronalda04)
No you don't as a mole is avagadro's constant amount of particles; which can be either molecules (NH3) or atoms (N or H)
so if it asks for atom I times by 2
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3 years ago
#8
(Original post by mynameisno123)
dont I need to x by 2 because there are 2 molecules ( nitrogen and hydrogen)
noooooo! you've got 30 moles of ammonia which is 30 x 6.022x1023 ammonia molecules (I think)
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3 years ago
#9
(Original post by mynameisno123)
so what if it asks me for atoms?
You do the exact same multiply by avagadros
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#10
(Original post by izzy55555)
noooooo! you've got 30 moles of ammonia which is 30 x 6.022x1023 ammonia molecules (I think)
thanks! what happens if it asks me how many ATOMS are in 30.0 of ammonia
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3 years ago
#11
(Original post by mynameisno123)
so what if it asks me for atoms?
You would just base it on the number of moles.

So take this # = Number of Atoms
n = number of moles
Avagadro constant (can't remember the symbol)
# = n times the Avagadro constant
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#12
(Original post by ronalda04)
You do the exact same multiply by avagadros
But I have a part a and part b in my question
part a ask for how many molecules in 30 moles of ammonia
and part b asks for how many atoms in.....
I can't possibly have the same answer
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3 years ago
#13
(Original post by mynameisno123)
But I have a part a and part b in my question
part a ask for how many molecules in 30 moles of ammonia
and part b asks for how many atoms in.....
I can't possibly have the same answer
gosh that's a weird question (what exam board are you??)

My guess is that you would use the ratio of atoms in the ammonia molecule to help you :
so 30 x 3 x avogadros constant for atoms of hydrogen

(could be wrong though sorry).
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3 years ago
#14
You multiply the number of molecules in 30 mol of NH3 by 4 to get the number of atoms as NH3 has 4 atoms per molecule (3 hydrogen atoms and 1 nitrogen atom).
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