Câu2
a) 2Na + O2 ---to--> 2Na2O
Na2O + H2O -----> 2NaOH
NaOH + HCl -----> NaCl + H2O
NaCl + AgNO3 -----> NaNO3 + AgCl
b) 2Cu + O2 -----> 2CuO
CuO + HCl -----> CuCl2 + H2O
CuCl2 + Ba(OH)2 -----> Cu(OH)2 + BaCl2
Cu(OH)2 ---to--> CuO + H2O
câu3
đổi 200ml=0,2l
nKOH = 5,6/56=0,1mol
pt : KOH + HCl -----> KCl + H2O
n pứ: 0,1----->0,1-------->0,1
CM(HCl)=0,1/0,2=0,5M
mKCl=0,1.74,5=7,45g