Final answer:
Magnesium reacts with steam to produce magnesium hydroxide and hydrogen gas, but with cold water the reaction is negligible for solid magnesium, typically leading to 'NR' (No Reaction) being the expected result for this pair of reactants.
Step-by-step explanation:
When examining the pair of potential reactants, magnesium and water, it is important to use the activity series to determine if a reaction will occur. Magnesium is an active metal, and it reacts with water to a limited extent by releasing hydrogen gas and forming magnesium hydroxide, primarily when the water is hot or when the magnesium is in the form of a fine powder. However, with cold water, the reaction is often negligible, so we might only note a reaction with steam. The balanced chemical equation for the reaction of magnesium with steam can be written as:
- Mg(s) + 2H2O(g) → Mg(OH)2(s) + H2(g)
If using cold water, we would write 'NR' to indicate that no reaction would occur under standard conditions with solid magnesium and liquid water. For the purposes of a high school homework assignment, we would generally consider no reaction to occur.