# GCSE science question help?

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#1
What mass of iron(II) sulfate would be needed to provide 28 grams of iron?
Remember to give the unit.

Relative atomic masses: O = 16; S = 32; Fe = 56.
Relative formula mass for this FeSO4 = 152

Can some one pls tell me step by step how to do it
thanks =) x
1
11 years ago
#2
mol = mass / Mr
so mol Fe = 28/56 = 0.5

therefore

mass = mol x Mr = 0.5 x 152 = 76grams

(This is what i'd do, it might be wrong in which case - sorry )
1
#3
you are right btw
hahaha i knew what the answer was but i didn't know how to solve it tbh
its the techer who didnt explain how to do it properly
thanks x

(Original post by TwirlGirl)
mol = mass / Mr
so mol Fe = 28/56 = 0.5

therefore

mass = mol x Mr = 0.5 x 152 = 76grams

(This is what i'd do, it might be wrong in which case - sorry )
0
11 years ago
#4
(Original post by zahir27)
you are right btw
hahaha i knew what the answer was but i didn't know how to solve it tbh
its the techer who didnt explain how to do it properly
thanks x
phew it wouldn't have boded well if i was wrong..got an A2 chemistry exam next week
0
#5
haha well good luck then
I got mine tommorow
so doing some hardcore revision ahaha

(Original post by TwirlGirl)
phew it wouldn't have boded well if i was wrong..got an A2 chemistry exam next week
0
11 years ago
#6
The method I use is to:

56/56 = 1

152/56 = 2.71428...

Then 2.71428... X 28 = 76g
1
#7
Now this is even more easier ahaha
thanks x

(Original post by MrMonopoly)
The method I use is to:

56/56 = 1

152/56 = 2.71428...

Then 2.71428... X 28 = 76g
0
11 years ago
#8
(Original post by MrMonopoly)
The method I use is to:

56/56 = 1

152/56 = 2.71428...

Then 2.71428... X 28 = 76g
That's the method I always use. My teacher used to do it the other way during lessons it just gets so confusing. This makes it a lot easier, and the questions they give us in the exam should always be able to be done without using moles.
0
9 years ago
#9
(Original post by TwirlGirl)
mol = mass / Mr
so mol Fe = 28/56 = 0.5

therefore

mass = mol x Mr = 0.5 x 152 = 76grams

(This is what i'd do, it might be wrong in which case - sorry )
I can confirm this is correct. How was your exam?
0
2 years ago
#10
I understand but where did you get 28 from??
0
2 months ago
#11
the 28 is the mass of the compound, in this case it will be 28 grams and you need to do mass/relative atomic mass
0
2 months ago
#12
(Original post by jrdoctorfudge)
the 28 is the mass of the compound, in this case it will be 28 grams and you need to do mass/relative atomic mass
Hiya! This thread was made in 2010 you can see the timestamp in the top right hand corner of each post
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