# Homework Help: Stoichiometry reaction of FeCr2O4 with K2CO3

1. May 10, 2013

### th3whit3fang

1) K2CrO4 is produced by the reaction of FeCr2O4 with K2CO3 and O2 in a high temperature. This reaction also produces Fe2O3 and CO2.
If 169 kg FeCr2O4 reacts with 298 kg K2CO3 and 75 kg O2 and so it produces 194kg K2CrO4 then calculate the efficiency of this reaction.

2) The equations is: 4 FeCr2O4 + 3 K2CO3 + 7 O2 --> 8 K2CrO4 + 2 Fe2O3 + 8 CO2
169 kg 298 kg 75 kg 194 kg

3) I first calculated the weights (2 Fe2O3 + 8 CO2) which were missing:
weight(2 Fe2O3 + 8 CO2) = (169 kg + 298 kg + 75 kg ) - 194 kg = 348 kg
and ther for the efficiency, i divided the weight of 8 K2CrO4 by 348 kg: 194 kg/ 348 kg = 55.7 %

It wasn't correct .. the correct answer is 66,2 %.

Last edited by a moderator: May 10, 2013
2. May 10, 2013

### Staff: Mentor

Potassium is not balanced (nor oxygen, nor carbon).

This is a limiting reagent problem. Calculate how much K2CrO4 should be made from given amounts of reactants.

3. May 10, 2013

### th3whit3fang

Sorry, i made a mistake while typing. it should be:

4 FeCr2O4 + 8 K2CO3 + 7 O2 --> 8 K2CrO4 + 2 Fe2O3 + 8 CO2

Thank you and i have another questi0n: can K2CrO4 the smallest limiting reagant?

i took it as the smallest limiting reagent .. and i calculated the weight of the other susbstances...

and then i divided the weight of K2CrO4 by the weight of FeCr2O4 + K2CO3 + O2.. is this how you calculate the efficiency ?

Last edited by a moderator: Jan 15, 2014