Question

1. (a) Calculate the formula mass of Fe2(SO4)3.

(b) What is the molar mass of Fe2(SO4)3?

(c) What is the mass of 0.2000 mole of Fe2(SO4)3?

2. Calculate the number of atoms in 27.0 g of pure silver.

Answer 1

Iron: 55.85g /mole
Sulfur: 32.06g/mole
Oxygen: 16.00g/mole

I can't recall but I think a and b are the same?
So 55.85x2=111.7 g /mol
32.06x3=96.18 g /mol
16.00x12=192.0 g / mol

399.9 g /mol

c) 0.2000 mol x 399.9 g /mol = 5.001x10^-4

Answer 2

I also think that molar mass and formula mass are the same....
I am confused in part c. Don't need to have 27.0 in the equation?

Answer 3

isn't 0.2000 mol x 399.9 g /mol = 79.98 ??

Answer 4

No, I think those are separate questions.

Number 2:

27.0g Ag x 1 mol / 107.87 g Ag x 6.022x10^23 / 1 mol = 1.51 x 10^23 atoms Ag

Answer 5

And yes, I think I must be very tired, lol.. Sorry!

Answer 6

never mind. thank you

Answer 7

would you kindly help me with another question?

Answer 8

I can try

Answer 9

Calculate the mass of
(a) 0.200 mol of chlorine atoms.
(b) 0.200 mol of chlorine molecules.
(c) chlorine which contains the same number of molecules as there are in 1.20 mol of water.

I am confused in masses and mole, what is the formulas about masses and mole?

Answer 10

Ok, if you are given moles and it asks for atoms, then you use Avogadro's number. If you are given moles and it asks for molecules, you still use Avogadro's number. So a and b would be the same for this one.

Answer 11

Do you know my question? Biochem? lol

Answer 12

I am not studying Bio but Chem, sorry that I cannot understand the question about bio...

Answer 13

lol me either...

Answer 14

atoms and molecules are not the same right?

Answer 15

well no, but Avogadro's number is used to calculate both. http://science.howstuffworks.com/avogadros-number.htm

Answer 16

I mean the definition of atoms and molecules.

Answer 17

Well a molecule is made up of multiple atoms

Answer 18

oh I almost forgot it .......

Answer 19

the mass of 0.200 mol of chlorine atoms
the moles is 0.200 right?

Answer 20

the number of mole is 0.200?

Answer 21

the question above was the number of molecules/atoms in 0.200 moles of chlorine

Answer 22

oh yes

Answer 23

there are 0.200 mol of chlorine atoms and I need to find out the mass right?

Answer 24

simply convert from moles to atoms...

.200 mol x 6.022x10^23/mol = 1.20 atoms/molecules of chlorine...You do NOT need to find the mass for this...

Answer 25

6.02*10^(23)*0.200=1.204^(23) right

Answer 26

ummm...

Answer 27

yep that works too

Answer 28

Remember sic figs

Answer 29

but the question is asking for the mass....isn't it?

Answer 30

I don't really know how to say this so you'll get it lol...No.

Answer 31

...

Answer 32

part b is the same as part a?