Simple chemistry problems in junior high school. A couple of junior high school chemistry questions

The second is because all the elemental iron can be dissolved with CuSO4, and one of the isolates is generated, copper, which will not produce tail gas and will not cause pollution to the environment. Of course, the hydrogen produced by the first type will not cause pollution to the environment, but the operation is more troublesome, and the method is not as simple as the second method to dispose of the exhaust gas and ignite the exhaust gas at the end of the device.

When considering the experiment, it is necessary to consider the feasibility, scientificity, and simplicity of the experimental device.

The first is good, because the generated copper will adhere to the iron surface and prevent the reaction from taking place further, so it cannot be separated completely, and the first type is good, concise and fast.

First, it's quick and easy. Moreover, copper sulfate is more expensive than dilute hydrochloric acid, and it is also more frugal for testing.

The rupture of molecules and the recombination of atoms.

One has gas generation, one has precipitation, and the other has no obvious phenomenon).

4.A separating funnel, a test tube, a round plastic plate with holes, a two-hole rubber plug (what else is the puzzle, .).Good luck with your learning progress)

1. None of the three gases reacts with NaOH, so HCl will react with NaOH and be excluded. SO2 in C will react with NAOH and be excluded. CO2 in D will react with NaOH and be eliminated. In summary, the answer to this question is A.

2. The microscopic essence of chemical reactions is atomic recombination. In layman's terms, the atoms that make up the reactants are separated from each other and rematched to form a new substance.

3. There are many such substances, such as sodium carbonate: reaction with HCl will produce gas, reaction with BACl2 to form precipitation, and KNO3 will not react. You can judge it from the phenomenon.

4. Put sodium carbonate powder in the Erlenmeyer flask, and dilute hydrochloric acid in the separating funnel (the separating funnel has a switch to control the liquid flow rate). The two form a simple gas generating device.

1、a。It cannot be used to dry acid gases.

2. The process by which atoms are recombined into new molecules.

3. Gas, BACL2 precipitate, KNO3 no phenomenon 4, U-shaped test tube and metal filter.

1: a, non-reaction is the premise 2: the gain and loss of electrons outside the nucleus 3;Silver chloride 4; Qipu generator.