Question

Calculati
nr moli a 128g cupru
cati atomi sunt continuti in 0,001 moli de azot
cati neutroni se gasesc in 7,8g de potasiu
Se dau masele atomice
A cu =64
An =14
Ak=39
Zk=19

Answer 1

n=nr. de moli          m=masa subst. ( g )       M=masa molara ( g/moli )

n=m: M

n=128g : 64g/moli=2moli Cu

1mol azot-----------6,023 .10 ²³ atomi azot

0,001 moli---------------x

x=0,001 .6,023 .10²³ atomi azot =

1mol K -----> 39 g K

n=m:M

n=7,8g : 39g/moli=0,2 moli K

A=39------>39-19=20 n [neutroni ]

1mol K -------------------20 .6,023 .10²³ n

0,2 moli K-----------------y

y=0,2 . 20 .6,023 .10²³  n =