Question

A mixture of sodium oxide and calcium oxide are dissolved in water and saturated with excess carbon dioxide gas. The resulting solution is __________ and it contains-
A) Basic $NaOH$ and $Ca{{(OH)}_{2}}$
B) Neutral $N{{a}_{2}}C{{O}_{3}}$ and $CaC{{O}_{3}}$
C) Basic $N{{a}_{2}}C{{O}_{3}}$ and $CaC{{O}_{3}}$
D) Acidic $NaOH$ and $CaC{{O}_{3}}$

Answer 1

Hint: The formulae of sodium oxide is $N{{a}_{2}}O$ and that of Calcium oxide is $CaO$
The salts formed from the strong bases and weak acids will be basic in nature and the salts formed from strong acids and weak bases will be acidic in nature.

Complete step by step answer:
So here in the question, it is given that the sodium oxide and the calcium oxide is dissolved in water and the excess of carbon dioxide is dissolved and makes the solution saturated. Now we have to predict the nature of the resulting solution and have to say about the compounds present in the solution.
So now let’s write the combined equation of all the compounds,
$N{{a}_{2}}O+CaO+{{H}_{2}}O+C{{O}_{2}}\to N{{a}_{2}}C{{O}_{3}}+CaC{{O}_{3}}$
So here we know that the products formed is $N{{a}_{2}}C{{O}_{3}}$ and $CaC{{O}_{3}}$
$N{{a}_{2}}O+CO\to N{{a}_{2}}C{{O}_{3}}$
$CaO+CO\to C{{a}_{2}}C{{O}_{3}}$
Now we have to see whether the solutions formed are acidic or basic in nature.
For that we should know whether $N{{a}_{2}}C{{O}_{3}}$ and $CaC{{O}_{3}}$ is basic or acidic.
$N{{a}_{2}}C{{O}_{3}}$ is a salt of weak carbonic acid and a strong base $NaOH$.
${{H}_{2}}C{{O}_{3}}+NaOH\to N{{a}_{2}}C{{O}_{3}}$
Carbonic acid is a weak acid and $NaOH$ is a strong base, hence the salt formed will have $pH$value greater than 7, i.e. it is basic in nature.
Similarly $CaC{{O}_{3}}$ is the salt of weak carbonic acid and a strong base Calcium hydroxide, $Ca{{(OH)}_{2}}$.
${{H}_{2}}C{{O}_{3}}+Ca{{(OH)}_{2}}\to CaC{{O}_{3}}$
So,$CaC{{O}_{3}}$ will be basic in nature.
Hence the solution formed will be basic in nature and contains $N{{a}_{2}}C{{O}_{3}}$ and $CaC{{O}_{3}}$

The correct option for this question is, option C.

Note The salt formed from strong acid and a strong base will have the $pH$ value equal to 7, which is neutral.
For salts formed from strong acid and weak base the $pH$ value will be less than 7 i.e. tit will be acidic
The salts formed by the combination of strong base and weak acid will have the $pH$ value greater than 7, hence will be basic in nature.