(m) During distillation, the thermometer is used to measure the temperature of the separated fraction, that is, the boiling point of the substance being distilled. The mercury bulb of the thermometer should be located near the branch opening of the distillation flask, and the condenser tube should enter water from the opening. , water flows out of the upper port to ensure that the water fills the condenser tube and achieves full condensation. In the picture, the mercury ball of the thermometer is inserted too deep, and the cooling water inlet and outlet are marked backwards.

So the answer is: ① Thermometer mercury The ball is inserted too deep; amp; upper bsp; ② The cooling water inlet and outlet are marked backwards;

(middle) The main instruments in the distillation device include distillation flask, condenser tube, horn tube, Erlenmeyer flask, alcohol Lamp, a is the distillation flask, B is the condenser tube,

So the answer is: distillation flask; condenser tube

(m) The principle of distillation is based on the different boiling points of miscible liquids To separate the components, fix the distillation flask on the iron stand, install a separatory funnel on the distillation flask, and connect the air guide pipe. You should first check the air tightness of the device. If the device does not leak, add the liquid reactants and start Reaction to produce gas,

So the answer is: test the air tightness of the device;

(Yes) During the experiment, in addition to adding the mixture solution to be separated, in A, in order to prevent the liquid In case of sudden boiling, broken porcelain pieces should be added,

So the answer is: zeolite (or broken porcelain pieces); to prevent the liquid from boiling;