19. Determină numărul de moli de atomi din:
a) 6 g atomi de hidrogen;
b) 40 g atomi de calciu;
c) 60 kg atomi de oxigen;
d) 15 kg atomi fosfor.
20. Determină masa (g) pentru:
a) 5 moli azot;
b) 2 moli uraniu;
c) 3 moli fer;
d) 4 moli nichel;
e) 10 kmoli fluor;
f) 2,5 kmoli neon.
21. Calculează numărul de atomi din:
a) 2 moli magneziu;
c) 0,5 kmoli argint;
e) 120 kg carbon;
22. Determină numărul de electroni resnent.
b) 0,5 moli argint;
d) 120 g carbon;
f) 3,5 g litiu.
Răspunsuri la întrebare
Răspuns:
a) n = m/M = 6/2 = 3 moli H2
1 mol H2...................2*NA = 2*6,022*10^23 atomi
3 moli H2.......................x = 36,132*10^23 atomi
b) n = m/M = 40/40 = 1 mol Ca
1 mol Ca = NA = 6,022*10^23 atomi
c) n = m/M = 60/2 = 30 kmoli = 30000 moli H2
1 mol H2...................12,044*10^23 atomi
30000 moli H2............x = 3,6132*10^28 atomi
d) n = m/M = 15/31 = 0,4838 kmoli = 483,87 moli P
nr atomi = 483,87*NA = 2,91387*10^26 atomi
2. a) n = m/M => m= n*M = 5*28 = 140g N2
b) n = m/M => m = 2*24 = 48g Mg
c) n = m/M => m = 3*56 = 168g Fe
d) m = 4*59 = 236g Ni
e) .......
f) m = 2,5*20 = 50kg = 50000g Ne
a) 1 mol Mg....................,6,023*10^23 atomi
2 moli Mg.......................x=2*6,023*10^23 atomi
b) 0,5 kmoli Ag=500 moli Ag
1 mol Ag..................6,023*10^23 atomi
500 moli Ag.................x atomi
x=6,023*500*10^23 atomi
c) MC=12g/mol
n=m/M=120/12=10 moli C
1 mol C................6,023*10^23 atomi
10 moli C..............x=6,023*10^24 atomi
d) n=m/M=120/12=10 kmoli C = 10000 moli C
1 mol C.................6,023*10^23 atomi
10000 moli C..........x=6,023*10^27 atom