A level Chemistry help!

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

Reply 1

ronalda04

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!

(edited 6 years ago)

Reply 2

username2703565

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)

Reply 3

Kaneki Amano

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

Reply 4

username2703565

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?

Reply 5

ronalda04

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)

Reply 6

username2703565

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

Reply 7

izzy55555

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)

Reply 8

ronalda04

Original post by mynameisno123

so what if it asks me for atoms?

You do the exact same multiply by avagadros

Reply 9

username2703565

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

Reply 10

Kaneki Amano

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

Reply 11

username2703565

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

Reply 12

izzy55555

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).

Reply 13

NiceB8M8

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).