Question

When the following reaction is balanced with the lowest possible whole number coefficients, what is the coefficient in front of oxygen (O2)? C2H6 + O2 yields CO2 + H2O

Answer 1

On the left we have 2 carbons so we need two on the right so now we have 2CO2
On the left we have 6 hydrogens so we need six on the left so now we have 3H2O
Current chemical formula: C2H6+O2 yields 2CO2+3H2O
On the right side we have 7 oxygen atoms so we need 7 on the left but it is O2 so the chemical formula now is:
C2H6+3.5O2 yields 2CO2+3H2O
Since you need whole numbers as the coefficients you need to multiply it all by 2 so the balenced chemical formula is:
2C2H6+7O2 yields 4CO2+6H2O
So the coefficent in the front of the oxygen is 7

Hope this helped! I am the smartest 6th grader in my school! :)