CÂU 3:
HCO3-+OH-==>CO3^2-+H2O
.....................0,003+x
Ca2+...+.....CO3^2-=>CaCO3
0,003+x....0,003+x
goi x la so mol Ca(OH)2 can them vao. ta co tong so mol ca2+=0,003+x
ma ta lai co x mol Ca(OH)2 => 2X mol OH-
nen ta co 2x=x+0,003=>X=0,003 => a=0,003.74=0,222 g
hoacdon gian hon ban thay so mol HCO3- =2 nCa2+ nen trong dung dich ton tai o muoi
Ca(HCO3)2
Ca(HCO3)2 +Ca(OH)2=>2CaCO3+2H2O
0,003..........>0,003 => a=0,003.74=0,222 g
=> Chọn B