Why does hydrogen burn before carbon?

Answer 1

There are two reasons. It burns faster because hydrogen is a gas and carbon is a solid. In general, almost all reactions occur much much faster in the gas phase because each molecule can much more easily encounter other molecules with which to react. Burning is a reaction where oxygen gas is combined with the burning material, and so a gas can mix much better and faster with oxygen gas then a solid can (because in a solid, only the molecules on the surface of the solid can react, whereas in a gas, all the molecules can potentially react). Also, a liquid is between a solid and gas in terms of this effect because the molecules are more available than in a solid because they are free to move within the container.

The second reason is that hydrogen is simply much more flammable than carbon is, so that even if the carbon was in the gas phase, it would still react more slowly than hydrogen. This has to do with the energy of the reactants and the energy of the products that are formed in the reaction. Hydrogen is a high energy molecule and thus is extremely flammable. Carbon is not nearly as high energy, and is therefore much less flammable.

Answer 2

It is 'before' helium because it only consists of 1 proton.