Answer
See answer below.
Work Step by Step
a) $(NH_4)_2PtCl_4(aq)+2\ NH3(aq) \rightarrow Pt(NH_3)_2Cl_2(s)+2\ NH_4Cl(aq)$
b) Number of moles of cisplatin:
$12.50\ g\div 300.04\ g/mol=0.042\ mol$
Mass of $(NH_4)_2PtCl_4$
$0.042\ mol\times 372.96\ g/mol=15.66\ g$
Volume of ammonia:
$0.042\ mol\ times 2/1\div 0.125\ M=0.672\ L= 672\ mL$
c) Number of moles of HCl:
$37.0\ mL\times 0.475\ M=17.58\ mmol$
Same as excess pyridine.
Number of moles of initial pyridine:
$1.50\ mL\times 0.979\ g/mL\div 79.10\ g/mol=18.56\ mmol$
Pyridine consumed:
$18.56-17.58=0.99\ mmol$
Cisplatin consumed:
$0.150\ g\div 300.04\ g/mol=0.50\ mmol$
Ratio: $2.00=x$
Compound formula:
$Pt(NH_3)_2Cl_2(C_5H_5N)_2$
