Question

Which one among the following statements is correct about a solution of borax in water?

• A. It is acidic because it contains $H _{3} BO _{3}$ and $NaOH$
• B. It dissociates into $NaBO _{2}$ and $B _{2} O _{3}$
• C. It is neutral because it contains $NaOH$ and $H _{3} BO _{3}$
• D. It is alkaline because it contains $NaOH$ and $H _{3} BO _{3}$

Answer 1

Answer: (D)

Chemical formula of borax is $Na _{2}\left[ B _{4} O _{5}( OH )_{4}\right] .8 H _{2} O .$ It is a salt of strong base which is $NaOH$ and a weak acid, that is $H _{3} BO _{3}$. Thus, borax is basic in nature because a strong base is added in weak acid. Hence, resultant aqueous solution of borax will be basic in nature. The solution of borax in water is

$Na _{2} B _{4} O _{7}+7 H _{2} O \longrightarrow 2 NaOH +4 H _{3} BO _{3}$