What is he small whole number that appears in front of a formula in a chemical equation?

Answer 1

The number in front of the different formulae within a chemical equation tells you how many molecules of that type are needed to react with the other molecules, as well as how many molecules of each product are produced. For example, when ethanol (alcohol) undergoes combustion with oxygen to produce water and carbon dioxide...

CH3CH2OH + 3O2 --> 3H2O + 2CO2

...for every molecule of ethanol, you need 3 molecules of oxygen for it to react with, and 3 molecules of water and 2 molecules of carbon dioxide will be produced. Of course, reactions don't generally involve just a few molecules. Really, these number give you a ratio of reactants and products.

In a real situation, 1000 molucules of ethanol might react with 3000 oxygen molecules to produce 3000 water molecules and 2000 molecules of carbon dioxide (because 1:3:3:2 = 1000:3000:3000:2000 = 2:6:6:4 etc.)

To work out what these numbers are can be a little tricky, but you basically have to make sure that the number of each element is the same on both sides of the equation (in the equation above, you can count 2 x carbons, 6 x hydrogens and 7 x oxygens on each side of the arrow).

Hope this helps!

Answer 2

The subscript

Number of atoms of that element in the molecule.

Answer 3

This is a coefficient - the number of atoms and molecules involved in a chemical reaction.

Answer 4

It is the coefficient.

Answer 5

coefficient