| (1) experimental comparison (2) reddish-brown solid becomes black to remove the unreacted CO, to prevent pollution of the air (3) ② ③ ① ④ ⑤ small |
| Test analysis: (1) A experiment is to Explore the movement of molecules, beaker ③ and beaker ② to form a contrast (2) B experiment, the chemical equation occurs in the hard glass tube: 3CO + Fe 2 O 3 high temperature 2Fe + 3CO 2, so the phenomenon is a reddish-brown solid into black, because carbon monoxide is toxic, so can not be allowed to excessive carbon monoxide emissions into the air, so the role of the alcohol lamp at the end of the device is to remove no reaction of CO, to prevent air pollution (3) the experimental steps of crude salt purification: dissolution, filtration, evaporation, calculate the yield, so the C experiment, if you want to remove the insoluble impurities in the crude salt, the correct procedure is ② ③ ① ④ ⑤, if ② ③ ① of the steps of the preparation of 50 gl6% of sodium chloride solution, due to the impurities contained in the crude salt did not go out, so that the mass of sodium chloride is smaller, so the preparation of the solution, the quality of sodium chloride, the quality of sodium chloride, the quality of sodium chloride is smaller than that of the solution, so the preparation of the solution, the quality of sodium chloride is smaller than that of the solution, the quality of the solution. |