Question

$0.001 \,mol$ of $\left[ Co \left( NH _{3}\right)_{5}\left( NO _{3}\right)\left( SO _{4}\right)\right]$ was passed through a cation exchanger and the acid coming out of it required $20 \,mL$ of $0.1\, M \,NaOH$ for neutralisation. Hence, the complex is

• A. $\left[ Co \left( NH _{3}\right)_{5}\left( SO _{4}\right)\right] NO _{3}$
• B. $\left[ Co \left( NH _{3}\right)_{5}\left( NO _{3}\right)\right] SO _{4}$
• C. $\left[ Co \left( NH _{3}\right)_{5}\right] NO _{3} \cdot SO _{4}$
• D. none of these.

Answer 1

Answer: (B)

Millimoles of acid $=20 \times 0.1=2$ millimoles $=0.002$ moles

If $0.001 \,mol$ is neutralising $0.002 $ moles of base. Thus, acid coming out should be dibasic.

$\left[ Co \left( NH _{3}\right)_{5}\left( NO _{3}\right)\right] SO _{4} \rightarrow\left[ Co \left( NH _{3}\right)_{5}\left( NO _{3}\right]^{2+}+ SO _{4}^{2-}\right.$