Question

Name one metal that will not react with cold water but will react with steam.
a.) Zinc
b.) Iron
c.) Calcium
d.) Magnesium

Answer 1

Hint:. To answer this question, you must remember that among the given metals, some react with water and give corresponding oxides and hydroxides. However, the transition metals among the given options do react with steam and give the corresponding oxides and hydrogen gas.

Complete step by step answer:
Before answering this, let us discuss the reaction of metals with water.
Metals form respective metal hydroxide and hydrogen gas when they react with water.
Metal + Water $\to $ Metal hydroxide + Hydrogen
Now let us go option wise and find out if they react with cold water or steam.
Firstly we have zinc. Zinc does not react with cold water and neither does hot water. It forms a protective layer of its insoluble hydroxide i.e. zinc hydroxide \[Zn{{\left( OH \right)}_{2}}\]. However, it reacts with steam vigorously and forms zinc oxide and hydrogen gas. The chemical equation for the reaction can be written as:
\[Zn(s)+{{H}_{2}}O(steam)\to ZnO(s)+{{H}_{2}}(g)\]

Then we have iron. Iron also does not react with cold or hot water. But, it also reacts with steam slowly and gives iron oxide and hydrogen gas. We can write the reaction as-
\[Fe(s)+{{H}_{2}}O(g)\to FeO(s)+{{H}_{2}}(g)\]

Next we have calcium. It reacts very slowly with cold water. It does not react with steam specifically. With water it forms calcium hydroxide and hydrogen gas. The reaction is-
\[Ca(s)+2{{H}_{2}}O(g)\to Ca{{\left( OH \right)}_{2}}(s)+{{H}_{2}}(g)\]

And lastly we have magnesium. Magnesium shows no reaction with cold water however reacts slowly with hot water to give its hydroxide. With steam, it reacts vigorously and produces an intense white light. We can write the reaction as-
\[Mg(s)+{{H}_{2}}O(steam)\to MgO(s)+{{H}_{2}}(g)\]
We can see from the above discussion that zinc, calcium as well as magnesium react with steam and so these are the required correct answers.
So, the correct answer is “Option A”.

Note: We should know that most of the metals do not react with water. However, alkali metals like sodium and potassium react vigorously with water. For example, by taking an example of sodium metal with water: Sodium metal forms sodium hydroxide and liberates hydrogen gas along with a lot of heat when it reacts with water.
\[Na+{{H}_{2}}O\to NaOH+{{H}_{2}}\]