Turn on thread page Beta
 You are Here: Home

# Amount of substance help watch

1. For this I did:

159.6g of Iron oxide ---> 111.6g of iron, so as 700 tonnes of iron produced, (700/111.6) x 159.6 = 1001.1 tonnes, is this correct? As the mark scheme says 1000 but I'm not sure if that's due to rounding.

For the second part

159.6g of iron oxide requires 84g of CO to fully react, so scaling this up to the 1000 of iron oxide would require 526.3g of carbon monoxide

so using the second reaction, 24g of coke produces 56g of carbon monoxide, so we would need (526.3/56) x 24 = 255.5g of coke? But the mark scheme says 527, so I'm pretty sure I've gone wrong somewhere in this whole question. Any help would be appreciated, thanks!
2. This is what I've done:

PART A

700 tonnes of Fe = 7x108 g of Fe

2 moles of Fe is produced from 1 mole of Fe2O3
RMM of Fe = 55.8g mol-1
RMM of Fe2O3 = 159.6g mol-1

Moles of Fe = Mass/RMM
= 7x108g / 55.8g mol-1
= 1.25x107 mol

There is a 2:1 ratio between Fe and Fe2O3, therefore
1.25x107 mol of Fe = 6.25x106 mol of Fe2O3

Mass of Fe2O3 = Moles x RMM
= 6.25x106 mol x 159.6g mol-1
= 9.975x108g
= 9.975x105kg
= 9.975x102 tonnes
= 991.5 tonnes (or 1000 tonnes rounded up)

PART B

1 mol of Fe2O3 requires 3/2 moles of CO from the second reaction
Moles of CO = 1.25x107 x (3/2)
=1.875x107 mol

There is a 1:1 ratio between CO and C and so
1.875x107 mol CO = 1.875x107 mol of C

Mass of C = Moles x RMM
= 1.875x107 mol x 12g mol-1
= 2.25x108g
= 2.25x105kg
= 225 tonnes

I see no possible way that it could be 527 tonnes...

Turn on thread page Beta
TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: April 16, 2013
Today on TSR

### Congratulations to Harry and Meghan!

But did you bother to watch?

### What do you actually do at University?

Poll

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE