Question

Name the gases evolved in each of the following cases:
A.Copper carbonate is heated strongly
B.Nitrogen combines with hydrogen
C.Action of dilute hydrochloric acid on sodium sulphate
D.Action of dilute hydrochloric acid on sodium carbonate
E.Glucose when oxidized

Answer 1

Hint: Formation of gas in a chemical reaction is a sign that the reaction may have occurred. The formation of bubbles when two liquids or a solid is mixed in a solution, is a sign that gas has been formed. The reaction can also be determined if there is a change in the temperature.

Complete answer:
Now, let’s see what the gases that evolve in the given question are.
Copper carbonate is heated strongly: When copper carbonate is heated strongly, it decomposes into copper oxide $(CuO)$ and carbon dioxide $(C{O_2})$ and a brisk effervescence of $C{O_2}$ is released. This is a decomposition reaction, and this occurs when heat is applied to a pure substance and the particles rearrange into two or more products. The colour of the compound changes from light green to black material.
$CuC{O_3} \to CuO + C{O_2}$
Therefore, the gas that evolves when copper carbonate is heated strongly is $C{O_2}$.
Nitrogen combines with hydrogen: When nitrogen combines with hydrogen, it forms ammonia, which is a gas.
${N_2} + {H_2} \to N{H_3}$
Balancing the equation, we get
${N_2} + 3{H_2} \to 2N{H_3}$
Therefore, the gas evolved when nitrogen combines with hydrogen is ammonia $(N{H_2})$.
Action of dilute hydrochloric acid on sodium sulphate: We can see that action of dilute hydrochloric acid on sodium sulphate with the help of its chemical reaction.
$N{a_2}S{O_4} + 2HCl \to 2NaCl + {H_2}S{O_4}$
The change in the free energy $(\Delta G)$ for this reaction is positive i.e. this reaction does not run because ${H_2}S{O_4}$ is stronger than $HCl$.
Action of dilute hydrochloric acid on sodium carbonate: When dilute hydrochloric acid is made to react with sodium carbonate, sodium chloride$(NaCl)$ is formed with the liberation of $C{O_2}$ and ${H_2}O$.
$N{a_2}C{O_3}(s) + 2HCl(aq) \to 2NaCl(aq) + C{O_2}(g) + {H_2}O(l)$
$C{O_2}$ releases a brisk effervescence, and when it is made to pass through lime water, the lime water turns milky. And if excess $C{O_2}$ is passed through the lime water, the solution turns clear again. This proves the presence of $C{O_2}$.
Therefore, the gas that is evolved in the action of dilute hydrochloric acid on sodium chloride is $C{O_2}$.
Glucose when oxidized: Glucose is oxidized by making it react with molecular oxygen; and this produces carbon dioxide and water.
The carbon atoms of glucose are oxidized i.e. they lose electrons and go to a higher oxidation state. Whereas, oxygen atoms are reduced and to a lower oxidation state.
${C_6}{H_{12}}{O_6}(s) + 6{O_2}(g) \to 6C{O_2}(g) + 6{H_2}O(l)$
Therefore, the gas that evolves when glucose is oxidized is $C{O_2}$.

Note:
When making a new substance from another, it carries out a synthesis. Reactants are converted into products, and the process is symbolized by a chemical reaction.
In the reactions done under normal laboratory conditions, matter is neither created nor destroyed and the elements are not transformed into other elements. That is why, the equations depicting reactions must be balanced.