Question

intr un amestec echimolecular, format din 6 moli continand atomii a 3 elemente consecutive se afla 144,528 * 10^23 electroni. identificati cele 3 elemente.

Answer 1

Notam elementele: A, B si C
A - z electroni (stim ca numarul atomic=nr de electroni), B - z+1 electroni si C - z+2 electroni
1mol element..........6,022*10²³ atomi..........z*6,022*10²³ electroni
deoarece avem amestec echimolecular => avem 2 moli de A, 2 moli de B si 2 moli de C
1mol A.......z*6,022*10²³electroni
1mol B.......(z+1)*6,022*10²³ electroni
1mol C. .....(z+2)*6,022*10²³ electroni
adunam => avem 3 moli amestec
3moli amestec.....(3z+3)*6,022*10²³ electroni
6moli amestec..................................x electroni
x=(6z+6)*6,023*10²³=144,528*10²³
6z+6=24 => 6z=18 => z=3
z+1=4 si z+2=5
A - Li(litiu) B - Be(beriliu), C - B(bor)