Question

Prussian blue is a deep blue pigment containing $Fe^{2 +},Fe^{3 +}$ and $CN^{-}$ ions. It has the formula $\left(Fe\right)_{7}\left(CN\right)_{18}$ . How many $Fe^{2 +}$ and $Fe^{3 +}$ ions are there per formula unit?

• A. $3Fe^{2 +}$ and $4Fe^{3 +}$
• B. $4Fe^{2 +}$ and $3Fe^{3 +}$
• C. $5Fe^{2 +}$ and $2Fe^{3 +}$
• D. $6Fe^{2 +}$ and $1Fe^{3 +}$

Answer 1

Answer: (A)

Prussian blue is a deep blue pigment is $ Fe _4\left[ Fe ( CN )_6\right]_3$