Question

A solution of sodium borate has a pH of approximately:

• A. < 7
• B.

  7

• C. 7
• D. between 4 and 5

Answer 1

Answer: (B)

7

Answer 2

Sodium borate in solution undergoes hydrolysis and gives a strong base (sodium hydroxide) and a weak acid $({{H}_{3}}B{{O}_{3}}).$ Hence, its solution will be basic and consequently the pH will be > 7. $N{{a}_{3}}B{{O}_{3}}+3{{H}_{2}}O\xrightarrow{{}}\underset{weak}{\mathop{{{H}_{3}}B{{O}_{3}}}}\,+\underset{strong}{\mathop{3NaOH}}\,$