Chem equation... balancing. I need help with the left side.?

Question

C3H8 + O2 ---> CO2 + H2O ---> 3CO2+4H2O

Teacher said I had to adjust left side of equation for this to be correct.

Answer 1

you have to balance the oxygen...since you have 10 oxygen atoms on the right side, you need a five in front of the O2 to balance!

final equation:  C3H8 + 5O2 ---> 3CO2 + 4H2O

Answer 2

count the oxygen atoms on both sides...

Answer 3

C3H8 + O2 ---> CO2 + H2O ---> 3CO2+4H2O

C3H8 + O2 => 3CO2 + 4H2O

To balance the equation:-

On the Left Hand Side (LHS) there are 3 atoms of C

On the Right Hand Side (RHS) there are3 atoms of C (1 each in each of the 3  molecules).

On the LHS there are 8 atoms of H.

On the RHS there are 8 atoms of H (2 in each of 4 molecules ).

On the RHS there are 10 atoms of O (2 each in 3 molecules of CO2 and 1 each in 4 molecules of H2O).

Consequently there should be 10 atoms of O on the LHS. However the equation shows 2 atoms of O. So to make 10 atoms of O a '5' is placed in front of O2, so it reads '5O2'. So to react 1 mole of C3H8, 5 moles of O2 are required. This produces 3 moles CO2 and 4 moles of H2O. The full equation is:-

C3H8 + 5O2 => 3CO2 + 4H2O

NB Remember oxygen exists as a diatomic molecule, that is each molecule of oxygen contains 2 atoms of oxygen - and is written as O2.

Hope that helps!!!!!