2. a. 2 Mg(s) + O2(g) 2 MgO(s)
Two moles of solid magnesium react with one mole of oxygen gas to produce 2 moles of solid magnesium oxide.
b. 2 H2(g) + O2(g) 2 H2O(l)
Two moles of hydrogen gas react with one mole of oxygen gas to produce 2 moles of liquid water.
c. NaOH(aq) + HCl(aq) H2O(l) + NaCl(aq)
One mole of sodium hydroxide reacts with one mole of hydrochloric acid (stomach acid) to produce 1 mole of liquid water and 1 mole of sodium chloride.
d. 2 Al(s) + Fe2O3(s) Al2O3 (s) + 2 Fe(l)
Two moles of solid aluminum react with one mole of Fe2O3(s) (we’ll learn how to name this rust soon) to produce 1 mole of solid aluminum oxide and 2 moles of liquid iron.
e. C(s) + H2O(g) CO(g) + H2(g)
One mole of carbon reacts with one mole of gaseous water (steam) to produce 1 mole of carbon monoxide gas and 1 mole of hydrogen gas.
3. In #2d, the iron is produced as a liquid. What does that tell you about the energy associated with the reaction?
The reaction releases a lot of heat. It is known as an exothermic reaction. If the opposite was true: if the reaction removed heat fro the environment, it would have been an endothermic reaction.