To balance an unbalanced equation, you need to add numbers to the left of one or more formulae. Here is one way to work out how to do this for the reaction between nitrogen and hydrogen.

This balanced chemical equation shows that 1 mole of magnesium reacts with 2 moles of hydrochloric acid to form 1 mole of magnesium chloride and 1 mole of hydrogen.

Key Laboratory of Enhanced Oil and Gas Recovery of Ministry of Education, Northeast Petroleum University, Daqing, Heilongjiang 163318, China ...

Hydrates, Flow Assurance & Phase Equilibria Research Group, Institute of GeoEnergy Engineering, Heriot-Watt University, Edinburgh EH14 4AS, U.K.