b.
2molAl se degaja 852kj
1mol.......................................x=.Q= -852/2 kj/mol=...................CALCULEAZA !
a. 1Kcal= 4,18Kj
Q=- 852/4,18kcal=203,8 kcal
2x27g.Al..........degaja...............203,8kcal
x...................................................256,57kcal
x=m=.........................calculeaza !!!!!.