Question

342 g of 20% by mass of ${\text{Ba(OH}}{{\text{)}}_{\text{2}}}$ solution (specific gravity =0.57) is reacted with 200 mL of 2 M ${\text{HN}}{{\text{O}}_{\text{3}}}$ according to the given balanced reaction.
${\text{Ba(OH}}{{\text{)}}_{\text{2}}}{\text{ + 2HN}}{{\text{O}}_{\text{3}}} \to {\text{Ba(N}}{{\text{O}}_{\text{3}}}{{\text{)}}_{\text{2}}}{\text{ + 2}}{{\text{H}}_{\text{2}}}{\text{O}}$
The nature of the final solution is:
A. Acidic
B. Neutral
C. Basic
D. None of the above

Answer 1

Hint: To find the nature of final solution, find the total number of moles of ${\text{Ba(OH}}{{\text{)}}_{\text{2}}}$ and ${\text{HN}}{{\text{O}}_{\text{3}}}$ present in the solution. If the number of moles are equal, then do know the nature of the molecule like dibasic, diacidic, monobasic etc.

Complete step by step answer:
-Now, first we will calculate the molar mass of barium hydroxide, i.e. ${\text{Ba(OH}}{{\text{)}}_{\text{2}}}$. It can be written as:
137 + 34 = 171 g/mol
-According to the question, 342 g of 20% by mass of ${\text{Ba(OH}}{{\text{)}}_{\text{2}}}$ solution will correspond to $\dfrac{{342 \times 20}}{{100 \times 171}}$.
-By solving this equation, the number of moles attained are 0.4
-Next, we are given that 200 mL of 2 M ${\text{HN}}{{\text{O}}_{\text{3}}}$ will correspond to $\dfrac{{200 \times 2}}{{1000}}$.
-By solving this equation, the number of moles attained are 0.4
As mentioned, the attained number of moles are equal.
-We know that ${\text{Ba(OH}}{{\text{)}}_{\text{2}}}$ is a diacidic base in nature, whereas ${\text{HN}}{{\text{O}}_{\text{3}}}$ is a monobasic acid.
So, we can say that the barium hydroxide is present in excess amounts in the solution.
Therefore, the final solution will be basic in nature.
Hence, the correct option is C.

Note: We have mentioned the diacidic base and monobasic acid. Here, diacidic base relates to the formation of two hydroxide ions on ionization by the one molecule of base. Second, if we have monobasic acid; it relates to the replacement of one hydrogen atom. We can say that when acid donates one hydrogen ion or atom to a base. So, don’t get confused between diacidic base, and monobasic acid.