Hydrogen and oxygen react under a specific set of conditions to produce water according
to the equation
2 H2(g) + O2(g) −→ 2 H2O(g).
How much hydrogen would be required to
produce 3.9 mol of water?
Answer in units of mol.

Consider the following reactions. (note: (s) = solid, (l) = liquid, and (g) = gas.) mg(s) + ½o2(g) → mgo(s) + 146 kcal/mole h2(g) + ½o2(g) → h2o(g), δh = -57.82 kcal/mole what type of reaction is represented by the previous two examples?