Question

When the equation `Li + O_2 -> Li_2O` is correctly balanced, what is the sum ofthe coefficients?

Answer 1

`4Li(s)+O_2(g) rarr 2Li_2O(s)`

Explanation:

The coefficients are selected so as to represent the conservation of mass. Is mass conserved in the given reaction? If it is not then it cannot be accepted as a representation of chemical reality. To make the arithmetic a bit easier we could write.........

`2Li(s) + 1/2O_2rarrLi_2O(s)`

See this [old answer.......](https://socratic.org/questions/how-do-you-write-a-balanced-chemical-equation)

Interestingly, lithium metal is one of the few materials that will react with (otherwise inert!) dinitrogen gas to give lithium nitride, `Li_3N`.

How would balance this equation?

`Li(s) + N_2(g) rarr Li_3N(s)`.........