Compulsory 2 Chemistry Why the liquid level of the A test tube rises

Chlorine and methane are consumed to form HCl, which is dissolved in water, and the pressure in the test tube decreases, so the liquid level rises.

The HCl produced by the reaction of methane and chlorine is absorbed by saturated salt water, and the pressure is reduced when the gas in the test tube is reduced, and the air pressure is stronger than the pressure of the test tube, and the water is pressed into the test tube, so that the liquid level rises.

First, methane and chlorine are irradiated with light to produce methyl chloride and HClThen, methylene chloride and the chlorine gas produced by HCL form methylene chloride and HCLThen, dichloromethane and HCl produce chlorine gas to form chloroform (also known as chloroform).

Finally, chloroform (also known as chloroform) and HCL produce chlorine gas to form tetrachloroform (also known as carbon tetrachloride).

In fact, there should be 5 kinds of products for the reaction of chlorine and methane, methyl chloride, methylene chloride, chloroform (also known as chloroform), tetrachloromethane (also known as carbon tetrachloride) and HCL

ch4+cl2---ch3cl+hcl

The 4 reactions were synchronized, and the 4 products were mixed.

The resulting product is easily soluble in water, i.e. the air pressure in the test tube will drop and the natural liquid level will rise.

In the experiment of measuring the oxygen content in the air, the oxygen in the gas collector cylinder was thought of due to the combustion of red phosphorus, and the pressure in the gas collector cylinder decreased.

Fe in A reacts with hydrochloric acid to produce hydrogen, but hydrogen will escape, and I don't think the liquid level in A will rise, so it may be that the person who asked the question is wrong.

b is the oxygen-absorbing corrosion of steel.

Negative electrode (Fe): 2Fe - 4e = 2Fe2 + positive electrode (C): 2H2O + O2 + 4e = 4OH - Total Reaction Equation:

2Fe + O2 + 2H2O = 2Fe(OH)2 It can be seen that the total reaction is oxygen consumption, and the gas in the tube is reduced, so the decrease in air pressure will suck the liquid in the tube, resulting in a decrease in liquid and a drop in the page.

See the encyclopedia for details.

The elemental iron can react with hydrochloric acid to form hydrogen, which leads to the increase of the air pressure in the branch tube and the discharge of the gas in the catheter, causing the liquid in the test tube in Figure A to rise The iron rust consumes oxygen, resulting in a decrease in the air pressure in the branch tube and a decrease in the liquid in the test tube in Figure B

This question is for the exam. Hydrochloric acid is a volatile gas that enters the tube on the left side. But this phenomenon is difficult to see in experiments, because volatile hydrochloric acid rarely enters the left side.

(1) Due to the reaction A + B C + D, the liquid level at A decreases in the U-shaped tube and the liquid level at B rises, and the reaction can be judged to be an exothermic reaction according to the nature of thermal expansion and contraction of the gas, so the answer is: exothermic;

2) Since the reaction of A+B and C+D is endothermic, the total energy of A and B is higher than that of C and D, so the answer is: high;

3) Chemical change is accompanied by changes in matter and energy, and the chemical energy in the substance is converted into heat energy and released through chemical reactions, so the answer is: chemical reaction; Thermal energy;

4) In the chemical reaction, the energy absorbed by the breaking of the old bond and the energy released by the formation of the new bond is generated, and the reaction is an endothermic reaction, then the energy absorbed by the breakage of the chemical bond of the reactant is lower than the energy released by the formation of the chemical bond of the product, so the answer is: low;

5) The reaction is an exothermic reaction, and does not need to be heated to occur, such as the reaction of aluminum and dilute hydrochloric acid, the chemical equation of the reaction is: 2Al+6HCl=ALCL3+3H2, so the answer is: 2AL+6HCl=ALCL3+3H2

Most of the evaporated bromine is dissolved in carbon tetrachloride.

Chlorine water reduces the iodine and extracts it with carbon tetrachloride, which is heavier than water and is in the lower layer.

The lower layer is purple and the upper layer is colorless.

Select C for this question

Analysis] Carbon tetrachloride is denser than water and is incompatible with water.

So when carbon tetrachloride and water are mixed. Carbon tetrachloride will be in the lower layer.

When KI and CL2 are mixed, elemental iodine is formed.

Elemental iodine has a higher solubility in carbon tetrachloride (than in water), so iodine will dissolve in carbon tetrachloride and will not dissolve in water, so it will not make the starch solution dissolved in water turn purple.

Rather, it is because it is dissolved in carbon tetrachloride, which reflects the color of iodine element, which is yellow.

As a result, the upper layer is water, which is transparent and colorless, and the lower layer is a carbon tetrachloride iodine solution, which is yellow.

The iodine element produced by 2Ki + Cl2 = I2 + 2KCl is dissolved in the lower layer of carbon tetrachloride and appears purple, so B. is selectedThe upper layer of liquid is colorless, and the lower layer of liquid is purple.

10 (1) Long neck funnel Alcohol lamp Sink (2) c Filtration Test tube mouth outlet (3) c

4) Marble dilute hydrochloric acid.

Carbon dioxide is soluble in water.

Place a glass rod dipped in clarified lime water at the mouth of the test tube to observe whether the lime water becomes turbid.

10. (1) a long-necked funnel; Alcohol burner; Flume.

2）2；Filtration; Gas collection cylinder mouth.

4）caco3;1CO2 is denser than air; Place the lit match on the mouth of the gas collector bottle and see if the match goes out.

11、（1）a；b；

2）b；Distilled water;

3）a；b；Ammonia is less dense than air; The water surface of the test tube is higher than the water surface of the tank; Ammonia is highly soluble in water, and the pressure in the test tube decreases.