Question

Metal compound A reacts with dilute hydrochloric acid to produce effervescence. The gas evolved to extinguish a burning candle. Write a balanced chemical equation for the reaction if one of the compounds formed is calcium chloride.
a) \[CaC{{O}_{3}}(s)+2HCl(aq)\to CaC{{l}_{2}}(s)+C{{O}_{2}}(g)+{{H}_{2}}O(l)\]
b) \[Ca(s)+2HCl(aq)\to CaC{{l}_{2}}(aq)+{{H}_{2}}(g)\]
c) \[CaC{{O}_{3}}(s)+HCl(aq)\to CaC{{l}_{2}}(s)+C{{O}_{2}}(g)+{{H}_{2}}O(l)\]
d) \[CaC{{O}_{3}}(s)+2HCl(aq)\to CaC{{l}_{2}}(s)+{{H}_{2}}C{{O}_{3}}\]

Answer 1

Hint: According to the question, the gas produced as a result of this reaction produces effervescence. There is one particular gas which has this property. The same gas also turns limewater milky.

Complete step by step answer:
Let us try and solve this question by going through the options and eliminating the wrong ones.
According to the question, the gas produced by reaction of metal with dilute hydrochloric acid produces effervescence. The same gas also extinguishes a burning candle. Carbon dioxide is a gas which has this property. From this, we can say that the product side must contain carbon dioxide. We can, therefore, eliminate the options which do not have carbon dioxide in its products, i.e., option (b) and (d).

Now, the options left with us are option (a) and option (c). As the base equation is the same in both the options, we can check the equations for its stoichiometric coefficients.
Look at the equation in option (c), we can see that Hydrogen is not balanced on both sides. On the reactant side, there is 1 mole of hydrogen (hydrochloric acid) whereas, on the product side, there are 2 moles of hydrogen (water).
Therefore, the answer is – option (a) - \[CaC{{O}_{3}}(s)+2HCl(aq)\to CaC{{l}_{2}}(s)+C{{O}_{2}}(g)+{{H}_{2}}O(l)\].

Additional Information:
Carbon dioxide is also used as a fire extinguisher, because it does not support combustion. The same can be seen by the fact that carbon dioxide extinguishes a burning candle.

Note: Calcium carbonate is also known by other names such as – calcite, limestone, chalk, etc. It is generally found in rocks in the form of minerals such as calcite, limestone and aragonite. It is also the main component in pearls and in the shells of marine organisms, snail shells and eggs.