Absolutely and that’s how chemistry works, basically you take some hydrocarbons(a bunch of H and C) and you add oxygens to them. I know it is weird to think of burning this way because you see the thing burnt disappear but remember that mass cannot be created or destroyed. Burning is really just adding two masses together and getting some waste heat in the process. What is left over from the process is going to be the weight of both the mass and it takes a lot of oxygen to burn jet fuel. Hence why the missions weigh so much more than the jet fuel.