# Getting chemical equations from word equations?

## I understand the basic concepts, but I don't know whether to use H2 for hydrogen or a single H for example (and for all BrNCLHOF problems) Right now I am stuck on: "Copper II Oxide is heated in the presence of Hydrogen. Copper metal and one other product (figure out its identity) are formed"

Dec 7, 2016

Equation:
$C u O \left(s\right) + {H}_{2} \left(g\right) \to C u \left(s\right) + {H}_{2} O \left(l\right)$

So your other product would be ${H}_{2} O$, or water.

#### Explanation:

So to answer your question of ${H}_{2}$ vs. $H$, I'd say always use ${H}_{2}$ when considering reactions. This is just since hydrogen gas is diatomic in its standard state (i.e. most thermodynamically favorable state), and hence when you are reacting something with hydrogen gas, it will more often than not be ${H}_{2}$.

One notable exception to this would be if you were considering acid-base reactions. In these types of reactions, you'll see the ${H}^{+}$ ion a lot, and this would obviously be just a single $H$.

Hope that helped :)