Question

The compound cisplatin, pt(nh3)2cl2 , has been studied extensively as an antitumor agent.

a. calculate the elemental percent composition by mass of cisplatin.

b. cisplatin is synthesized as follows: k2ptcl4 (aq) + 2nh3(aq) â pt(nh3)2cl2 (s) + 2kcl (aq) what mass of cisplatin can be made from 100.g of k2ptcl4 and sufficient nh3? what mass of kcl is also produced?

Answer 1

a. Elemental percent composition is the mass percent of each element in the compound.

The formula for mass elemental percent composition = $\frac{mass of element}{mass of compound}$   (1)

The molecular formula of cisplatin is $Pt(NH_3)_2Cl_2$.

The atomic weight of the elements in cisplatin is:

Platinum, $Pt = 195.084 u$

Nitrogen, $N = 14.0067 u$

Hydrogen, $H = 1 u$

Chlorine, $Cl = 35.453 u$

The molar mass of $Pt(NH_3)_2Cl_2$ = $195.084+ (2\times 14.0067)+(6\times 1)+(2\times 35.453)$ = $300.00 g/mol$

The mass of each element calculated using formula (1):

- Platinum, $Pt$ %

$\frac{195.084}{300.00} \times 100 = 65.23$%.

- Nitrogen, $N$%

$\frac{2\times 14.0067}{300.00} \times 100 = 9.34$%

- Hydrogen, $H$%

$\frac{6\times 1}{300.00} \times 100 = 2.0$%

- Chlorine, $Cl$%

$\frac{2\times 35.453}{300.00} \times 100 = 23.63$%

b. The given reaction of cisplatin is:

$K_2PtCl_4(aq)+2NH_3(aq)\rightarrow Pt(NH_3)_2Cl_2(s)+2KCl(aq)$

According to the balanced reaction, 1 mole of $K_2PtCl_4$ gives 1 mole of $Pt(NH_3)_2Cl_2$.

Now, calculating the number of moles of $K_2PtCl_4$ in 100.0 g.

Number of moles = $\frac{given mass}{Molar mass}$

Molar mass of $K_2PtCl_4$ = $2\times 39.0983+195.084+4\times 35.453 = 415.093 g/mol$

Number of moles of $K_2PtCl_4$ = $\frac{100 g}{415.093 g/mol} = 0.241 mole$.

Since, 1 mole of $K_2PtCl_4$ gives 1 mole of $Pt(NH_3)_2Cl_2$. Therefore, mass of cisplatin is:

$0.241 mole\times 300 g/mol = 72.3 g$

For mass of $KCl$:

Molar mass of $KCl$ = $39.0983 + 35.453 = 74.55 g/mol$

Since, 1 mole of $K_2PtCl_4$ gives 2 mole of $KCl$. Therefore, mass of $KCl$ is:

$0.241 mole\times 74.55 g/mol\times 2 = 35.93 g$