Question

$2.40g$ of the chloroplatinate of a mono acid-base on ignition gave $0.8g$ of platinum. Calculate the molecular weight of the base. (Given the atomic weight of $Pt=195g/mol$).

• A. $87.5g/mol$
• B. $34.6g/mol$
• C. $102.4g/mol$
• D. $111.0g/mol$

Answer 1

The correct option is A $87.5g/mol$

The formula of the chloroplatinate is $\left(BH{)}_2\right[PtC{l}_6]$.
$2.40$ g of chlorplatinate corresponds to $0.8$ g of Platinum.
$\therefore 195$ g of platinum will correspond to $\frac{2.40}{0.8}\times 195=585g$ of chloroplatinate.
The molecular weight of the base is $\frac{585-409.81}{2}=87.5g/mol$.

Here $409.81$ is the mass of $PtC{l}_6$.

Hence, option $A$ is correct.