## Chemistry and Chemical Reactivity (9th Edition)

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: $Pt(NH_3)_2Cl_2(C_5H_5N)_2$