Question

What number should be substituted for the question mark to balance the equation and why is that the correct number?

C3H8 +?O2 → 3CO2 + 4H2O + heat

A.
The number 7 is needed to balance the equation. The right side shows 3 oxygen atoms in carbon dioxide and 4 oxygen atoms in water for a total of 7 oxygen atoms.

B.
The number 5 is needed to balance the equation. The right side of the equation shows 10 oxygen atoms, so the left side needs 5 O2.

C.
The number 4 is needed to balance the equation. The right side shows 4 oxygen atoms, so the left side needs 4 oxygen atoms.

Answer 1

D.
The number 3 is needed to balance the equation. The right side of the equation shows 6 oxygen atoms, so the left side needs 3 O2.

Answer 2

@furnessj Sorry to bother you, but can you help?

Answer 3

\[O _{2}\] means two oxygen, and a large number means that many of what comes next... so \[3O _{2}\] will be 6 oxygen in total. try adding up the number of oxygen on the right of the equals. there must me that many on the left as well.

Answer 4

Oh, thankyou!!!!

Answer 5

@furnessj can you help me too :D

Answer 6

@beautifulnighmare what answer is it?? im really confused

Answer 7

C, sorry that I haven't been online, but yeah, it's c