1.5 gof brass containing Cu and Zn reasts with 3.0 M HNO_3 solution. The following reaction take place: Cu+HNO_3toCu^(2+)+NO_2(g)+H_2O Zn+H^(o+)+NO_(3)^(ɵ)toNH_(4)^(ɵ)+Zn^(2+)+H_(2)O (a). Calculate the percentage composition of brass. (b). How many " mL of " 3.0 HNO_3 will be required for completely reacting with 1.0 g of brass?

1.5 gof brass containing Cu and Zn reasts with 3.0 M HNO_3 solution. T

1.	1.5 gof brass containing Cu and Zn reasts with 3.0 M HNO_3 solution. The following reaction take place: Cu+HNO_3toCu^(2+)+NO_2(g)+H_2O Zn+H^(o+)+NO_(3)^(ɵ)toNH_(4)^(ɵ)+Zn^(2+)+H_(2)O (a). Calculate the percentage composition of brass. (b). How many " mL of " 3.0 HNO_3 will be required for completely reacting with 1.0 g of brass?
Answer» Solution :`CutoCu^(2+)+2e^(-)` `undersetunderset(x=5)(1+x-6=0)[H^(+)+e^(-)+HNO_(3))toundersetunderset(x=4)(x-4=0)(NO_(2))+H_(2)O` `Cu+2H^(o+)+2HCO_(3)to2NO_(2)2H_(2)O+Cu^(2+)` `Cu+4HNO_(3)to2NO_(2)+2H_(2)O+Cu^(2+)+2NO_(3)^(ɵ)` or `Cu+4HNO_(3)to2NO_(2)+2H_(2)O+Cu^(2+)+2H_(2)O` 1 " mol of "`Cu=4 " mol of "HNO_(3)-=2 " mol of "NO_(2)` Mole of `NO_(2)=(PV)/(RT)=(1xx1xx0.4)/(0.082xx298)=0.0425` mole of `Cu=(0.0425)/(2)=(0.0425)/(2)xx63.5=1.3462g` Weight of `Zn=1.5-1.3462=0.1538g` `% Zn=10.25%` `% of Cu=89.75%` `[ZntoZn^(+2)+2e^(-)]xx4` `8e^(-)+undersetunderset(x=5)(x-6=-1)(NO_(3)^(ɵ))+10H^(o+)toundersetunderset(x=-3)(x+4=+1)(NH_(4)^(o+)+3H_(2)O)` or `4An+10HNO_(3)toNH_(4)^(o+)+4An^(2+)+3H_(2)O` `4Zn+10HNO_(3)toNH_(4)NO_(3)+4Zn(NO_(3))_(2)+3H_(2)O` `=3xxV` `V=0.2011 L =20.11mL`