a)Na + ½Cl2 -> NaCl
b)
1mol..............58,5g
Na + ½Cl2 -> NaCl
5moli.............x=292,5g
292,5g..........100%
y.....................95%
y=292,5*95/100=277,875g NaCl
c)
c=md*100/ms
md=mNaCl=277,875g
ms=md+mapa=277,875+800=1077,875g solutie
c=277,875*100/1077,875=25,78%