1.Cu₂CO₃(OH)₂=malachit
Masa molara Cu₂CO₃(OH)₂=2*64+1*12+3*16+2*16+2*1=222g
222g..................80g O₂
100.....................x
x=80*100/222=36.03%O₂
2.Cu+Cl₂=CuCl₂
Masa molara CuCl₂=1*64+2*35.5=135g
1mol CuCl₂....................135g
4moli CuCl₂....................y
y=4*135/1=540g CuCl₂
z=masa pura de cupru
z=540*64/135=256g Cu pur
q=masa de cupru cu 10% impuritati
q=256*100/10
q=2560g Cu 10% impur