What does the number 4 in #4H_2O# tell you?

1 Answer
May 23, 2017

4 moles of.....


The number preceding a chemical formula in an equation relates to the number of moles of that substance that is reacting.

For example:

#2H_2 + O_2 -> 2H_2O#

means that 2 moles of hydrogen gas and 1 mole of oxygen gas react to form 2 moles of water.