20. a.1mol H2 are masa 2g( DIN TABEL)
5 mol m= 10g; se aplica relatia: n sau niu = m,g/M,g/mol
b.1 kmol =1000mol --> m= 1000molx2g/mol =======
21.Masa molara a Mg = 24g/mol
a. n= 36g/24g/mol => 1,5mol
b.2kmol N=2000mol N---.> m=2000molx14g/mol=========
22.se stie ca 1 mol de atomi sau molecule contin 6,023x10²³atomi sau molecule -numarul lui Avogadro
b.1mol Cu contine nr.lui Avogadro atomi Cu
o,5mol N= 0,5x6,023x10²³--> 3,o11x10²³atomi
Se va aplica relatia n sau niu = N particule/ nr.Avogadro
c.2 kmoli Ca =2000moli Ca
N = 2000mol X 6,023X10²³atomi/mol-->12,046x10²⁶ atomi
a. calculez nr.moli de H din masa data : n sau niu= 3g/1g/mol--> 3 molH
'' '' N= 3 molx 6,023x10²³ atomi/mol
