Limiting reagent problem? For the reaction C2H6+O2CO2+H2O

(1) Balance
(2) if 270 g C2H6 and 300 g O2 reacted, how many moles of CO2 were produced?
(3) How many grams excess leftover?

2 Answers
Feb 16, 2016

see below

Explanation:

Balanced Eqn
2C2H6+7O2=4CO2+6H2O
By the Balanced eqn
60g ethane requires 7x32= 224g oxygen
here ethane is in excess.oxygen will be fully consumed
hence
300g oxygen will consume 60300224=80.36g ethane
leaving (270-80.36)= 189.64 g ethane.
By the Balanced eqn
60g ethane produces 4x44 g CO2
hence amount of CO2 produced =44480.3660=235.72g

and its no. of moles will be 235.7244 =5.36 where 44 is the molar mass of Carbon dioxide

Feb 18, 2016

Balanced equation is C2H6+72O22CO2+3H2O

Explanation:

Balanced equation is C2H6+72O22CO2+3H2O

Alternatively, this can be written as 2C2H6+7O24CO2+6H2O

Find the number of moles of each reactant:

For C2H6, with molar mass 30 gmol1:

n=mM=27030=9 mol

For O2, with molar mass 32 gmol1:

n=mM=30032=9.375 mol

It might look as though we have an excess of O2, but remember that each 1 mol of C2H6 required 72 mol of O2, so in fact we have less oxygen than we need. Some C2H6 will remain unburned at the end of the reaction.

Divide the 9.375 mol by 72 to discover that 2.68 mol of C2H6 will react. Each mole of C2H6 produces 2 mol of CO2, so 5.36 mol of CO2 will be produced.

The remaining amount of C2H6 will be 92.68=6.32 mol. To find the mass of excess C2H6:

m=nM=6.3230=189.6 g