Answer: 3 O2
Explanation: This a combustion reaction where a hydrocarbon reacts with oxygen gas to form CO2 and H2O.
The balance equation is:
C2H5OH + 3O2 => 2CO2 + 3 H2O
The number of atoms in the reactant and product side is the same.
Reactant Product
C 2 2 x 1 = 2
H 5+1= 6 3x2 = 6
O (2x3) +1 = 7 3+ (2x2) = 7
So the equation is now balanced.
