(2) The average relative molecular mass of air is 29. If the relative molecular mass of a gas is greater than 29, the density of this gas is greater than that of air; If it is less than 29, the density is less than air. If the relative molecular weight of carbon dioxide is 12+ 16×2=44, the density of carbon dioxide is greater than that of air, and carbon dioxide can be collected by upward air discharge. If there is 50g limestone with 80% mass fraction in the conical flask, the mass of calcium carbonate is 50g×80%=40g, which can be made at most.
10044
40g？ x
10040g=44x
X = 17.6 g
So the answer is: (1) CaCO3+2hcl ═ CaCl2+H2O+CO2 ↑;
(2)44. Upward exhaust mode.17.6g. 。