Question

PLEASE HELP?

find the number of O atoms in 8.4 ✕ 10-3 g CuSO4·5 H2O

Answer 1

Recall that 1 mole has 6.022*10^23 molecules. Now look at hoe many O atoms are in 1 molecule of CuSO4.H2O

Answer 2

sorry for the late reply.

ok so there are 5 O atoms? or does the 5 in front of the H carry to the O for the 5H2O?

Answer 3

It does carry.

Answer 4

ok thank you, I never fully understood that. ok so ya 5 atoms. what now ?

Answer 5

Well you have to take into account the O's in the CuSO4 part. CuSO4.5H2O is a whole compound.

Answer 6

so 9 O's

Answer 7

Right. So you have 9 O's in every molecule, and there are 6.022*10^23 molecules in 1 mole of a substance.

Answer 8

ok side note. i get confused when the 6.022 stuff is like 1 mole. please explain? It's stupid I know but I kinda wanna understand what that fully means .

Answer 9

Ah ok. Well it means that in 1 mole of a substance, there are 6.022*10^23 number of molecules in it.

Answer 10

That number is called the Avogadro's constant. http://en.wikipedia.org/wiki/Avogadro_constant

Answer 11

so basically 1 mole equals 6.022*10^23?

Answer 12

Yup. Sorry didn't see your reply last night.

Answer 13

haha no worries.

Answer 14

Can you do it now?

Answer 15

ok so i set it up like

8.4 x 10^-3 x 1 x 9 O
-----
mass of CuSO4*5 H2O.

is that right?

Answer 16

Wait no. To find the number of moles you divide the mass with the molar volume. And then to find the number of molecules you multiply by the Avogadro's constant. And then to get the number of atoms you multiply by 9.

Answer 17

where do i inset avogadro?

Answer 18

insert*