Răspuns:
sarea este CuSO4
c= mdx100/ms---> md= cxms/100=20x40/100g= 8gNaOH
M,NaOH= 40g/mol
M,Na2SO4=142g/mol
2mol....................................................1mol
2NaOH + CuSo4---- > Cu(OH)2+Na2SO4
2x40g.......................................................142g
8g...............................................................x=m=14,2gNa2SO4
Explicație: