How to balance a chemical equation.

Balancing chemical equations can seem tricky at first, especially when starting out. But by following an order it becomes a quick and easy task.

For the sake of this question we'll balance this equation:
C5H12 + O2 → CO2 + H2O

It's easiest to start from left to right and work your way along until the equation is balanced, then any cancellation can be done.

1. C5H12 + O2 → CO2 + H2O

We can see there are 5 carbons on the left and only 1 on the right, so balance the carbons first

C5H12 + O2 → 5CO2 + H2O

2. C5H12 + O2 → 5CO2 + H2O

There are 12 hydrogens on the left but only 2 on the right, so multiply by 6 to balance.

C5H12 + O2 → 5CO2 + 6H2O

3. C5H12 + O2 → 5CO2 + 6H2O

Now the right hand side has much more oxygens than the left, 10 from the 5COand 6 from the 6H2O for a total of 16. So multiply the O2 on the left by 8 to get 16.

C5H12 + 8O2 → 5CO2 + H2O.

And there you go, the equation is balanced. Working systematically works for even complicated equations.

Youssef M. GCSE Biology tutor, GCSE Chemistry tutor, GCSE Maths tutor

1 year ago

Answered by Youssef, a GCSE Chemistry tutor with MyTutor

Still stuck? Get one-to-one help from a personally interviewed subject specialist


£18 /hr

Mabast H.

Degree: Physics (Bachelors) - Imperial College London University

Subjects offered:Chemistry, Physics+ 3 more

Further Mathematics
-Personal Statements-

“Undergraduate Physicist with lots of experience in teaching in different fields and age groups, looking to instil a passion for learning into students.”

MyTutor guarantee

£18 /hr

Hannah B.

Degree: Natural Sciences (Masters) - Nottingham University

Subjects offered:Chemistry, Science+ 2 more


“2nd-year Natural Sciences student at the University of Nottingham. Looking forward to meeting you!”

MyTutor guarantee

£22 /hr

Nketia O.

Degree: Pharmacy (Masters) - Durham University

Subjects offered:Chemistry, Physics+ 1 more


“Hello! My name’s Nketia. I got an A* in A-Level Biology and an A in A-Level Chemistry. I’m a second-year Pharmacy student who is ready to teach others.”

About the author

Youssef M.

Currently unavailable: for regular students

Degree: Dentisty (Bachelors) - Birmingham University

Subjects offered:Chemistry, Maths+ 1 more


“Who am I?Hello everyone, I'm Youssef and I'm a dental student at the University of Birmingham. Since a young age I've had a passion for science, one which I hope I can pass on to you too. A passion which I continue through studying d...”

MyTutor guarantee

You may also like...

Other GCSE Chemistry questions

Describe what you would see when a piece of potassium is placed on water. Why does this happen?

Explain what a hydrocarbon is, and suggest two properties of hydrocarbons that leave a fractioning column near the top.

Explain the atomic structure of an Atom?

A metal oxide has a relative formula mass (Mr ) of 81. The formula of this metal oxide is MO. Given that the relative atomic mass (Ar ) of oxygen is 16, what is the metal in the metal oxide?

View GCSE Chemistry tutors

We use cookies to improve your site experience. By continuing to use this website, we'll assume that you're OK with this. Dismiss