# Chem help..test tomorrow!! (1 Viewer)

#### Manda.found

##### New Member
hey!!
im freakin out cause tomorrow is my chemestry exam and i have no idea on some topic so i was wondering if u can help me! or any pointers...or any previous text papers
like when it comes to the mole concept...how do i actually work it out of its for example what mass of Fe2O3 can be made from 5.6g of iron?

thanks
manda

#### iEdd

##### Member
Manda.found said:
what mass of Fe2O3 can be made from 5.6g of iron?
For one mole of Fe2O3, you have 2 moles of Fe and 3 moles of O.

First work out the mass ratio of Fe:O in a mole or just a molecule of Fe2O3.
It is 55.845 x 2 : 16 x 3 = 111.69:48 = 2.326875:1 [by dividing both sides by 48]

Then all you need to do is divide 5.6g by 2.326875 and you get 2.4066613g [the amount of oxygen in the compound]. Add this to 5.6 and you get your total:
8.01g of Fe2O3.

#### rusty91

##### Member
u must know about the extraction method of aluminium oxide and the diagram for extracting it. its easy. you'll be fine

#### blackrosepetals

##### New Member
rusty91 said:
u must know about the extraction method of aluminium oxide and the diagram for extracting it. its easy. you'll be fine
omg really? we didnt do that in class...

i have my exams tomorrow as well

good luck everyone doing theirs!!

#### sle3pe3bumz

##### glorious beacon of light
rusty91 said:
u must know about the extraction method of aluminium oxide and the diagram for extracting it. its easy. you'll be fine
lol mines tomorrow. i learnt that today and think i should be fine for it. hope they dont ask that though. xD

#### fozzster22

##### Member
rusty91 said:
u must know about the extraction method of aluminium oxide and the diagram for extracting it. its easy. you'll be fine
omg why didnt you say that earlier?? lol I totally forgot about that prac so i just bullcrapped it. oh well

#### CleverDan

##### New Member
Manda.found said:
hey!!
im freakin out cause tomorrow is my chemestry exam and i have no idea on some topic so i was wondering if u can help me! or any pointers...or any previous text papers
like when it comes to the mole concept...how do i actually work it out of its for example what mass of Fe2O3 can be made from 5.6g of iron?

thanks
manda
well, for starters, it would help if you could spell the course right

You'd find the masses of iron and iron oxide; find out how many moles of iron you start with, halve it (because there is two parts of iron in iron oxide therefore half as many moles from what you started with) and then times it by the molar mass of iron oxide? idk. seems right to me

[[wow! my first post ever! there goes my posting virginity]]

#### MonKazzar

##### Member
AHAHAH i just did my chem test. FAILED it so badly. But then so did the rest of my class. =[