How to do chemistry test questions, chemistry lab questions.

When the teacher is doing experiments, you must carefully observe, including the teacher's every move, because the efficiency of the class will not be able to keep up with it after class. Try to ask some questions during the teacher's experiment, which will help you with the lab questions!

In fact, there are a lot of things to memorize in chemistry, you have to remember the experimental phenomena and operation precautions, and there will be no problem in doing the questions.

It's good to understand and memorize, the equation is the key, and it should be no problem to memorize it in combination with the physical and chemical properties of the reactant products. Then there is to do more questions, and some yin people have to do it to know.

In fact, chemistry is semi-liberal arts.

Some still have to be memorized.

Then I can only do more questions.

It is necessary to grasp the key. Understand the main point.

In fact, it is the process of reading the book before the experiment, close your eyes and imagine that you will do the experiment yourself, and you will not forget the steps the next day.

If conditions permit, you still have to conduct experiments by yourself, and you must have the guidance of a teacher, so that you will be more clear about the experiment and not easy to forget the details.

I think you should read more books and learn the language descriptions in the books. And you should observe more when you are doing experiments and keep the experimental phenomena firmly in mind. If you have time, you should pay more attention to the description of the experiment in the teaching materials!

Chemistry belongs to the nature of half-literate and half-rational, understanding and memory is very good, but always have to remember, if writing equations is a little slow, it means that the understanding is not deep enough or remember not enough, the test questions are usually to test the comprehensive ability, so you should also learn the knowledge points with a summary memory, when doing the questions can be handy to use the knowledge learned.

1) The function of device A is to remove water vapor.

The function of the C unit is to remove carbon dioxide.

2) In order to achieve the above - purpose, use the code of each device interface to indicate the correct connection sequence.

abefefcd

Experimental procedure: Take four test tubes, take a small amount of two colorless solutions and two black powders and put them in four test tubes.

Add purple litmus solution dropwise to the two colorless solutions. Phenomenon: One solution is red. There was no significant change in the other branch. Conclusion: The red solution is dilute sulfuric acid, and the other is sodium sulfate.

Dilute sulfuric acid with purple litmus solution was dropped into two black powder test tubes one by one. Phenomenon: A large number of bubbles are generated in a test tube, and the solids gradually dissolve.

The other tube is a black solid that gradually dissolves and the solution is blue. Conclusion: Iron is produced by bubbles, and copper oxide is produced by blue solution.

1. Take a little of each two liquids in the test tube, drop into the purple litmus solution, and turn red into sulfuric acid.

2. Take two parts of sulfuric acid into two test tubes, add a small amount of powder to each, the one that turns blue is cuo, and the one that produces bubbles is iron powder.

1.Direct flow of clarified lime water, if it becomes turbid, it is CO2 approached with a burning wooden stick, if it is extinguished, it is CO2

3.Drops of litmus solution turn red, indicating that it contains carbon dioxide.

4.If it is like clarified lime water, if it is turbid, and then it is dripping like dilute hydrochloric acid, oscillating or knowing, if the precipitation disappears and bubbles come out, it proves that there is carbon dioxide!

1.Volumetric bottled water, one hand to hold the bottom of the bottle, the other hand to hold the neck of the bottle, upside down, check whether there is leakage, repeat several times.

2. The appearance of the instrument is cleanThere are no impurities on the walls (white channels, residues, etc.).

3.Check whether the filtrate is cloudy, and if it is cloudy, it needs to be filtered again.

4.Observe whether the filtrate is clean, if the precipitate-related elements have no color, the filtrate should be treated with precipitant until no precipitate is precipitated after washing the filtrate and then adding precipitant.

5.The outer conduit of the closed system is ignited, and the combustion color is observed to see if the combustion color is blue.

6.Through potassium permanganate, sulfur dioxide has a certain reducing property.

7.Add some light metal salts to the solution and observe whether there is a liquid phase that is insoluble in water to determine whether the saponification reaction is complete. (The product can be salted).

8.Iodize and observe if it turns blue.

9.Silver nitrate is dropped into ammonia to observe the precipitation and gradually dissolve, and copper hydroxide can be added? It should be a test experiment, neither of which can test the acid in the aldehyde-based product, thinking that these two and formaldehyde can produce formic acid.

10.Hydrochloric acid is dropped into the product to observe for gas.

11.Drop into litmus reagent to observe the color.

12.Observe the reducibility of metals, the oxidation of non-metals.

13.Comparative experiments, with and without external comparisons, and the products are collected at the same time point.

14.React for a while, take out the iron sheets, wash and dry them repeatedly, weigh them, and compare them before use.

15.Observe the acidity and alkalinity of the aqueous solution, there will be certain changes, and you can also add a precipitant dropwise to the solution to detect bromine ions.

16.Compare the difficulty, cost and danger of the test, and select the simplest and best results based on the principle of low cost.

17.Advance assessment to prevent, effectively improve the surrounding environment, and avoid possible hidden dangers.

18.Averaged over multiple trials to see if the deviation was within an acceptable range. (Error vs. Expected Reference).

There is no absolute answer to the above, and it is recommended that the landlord study hard, which is quite basic.

Steps: Take the reaction solution and add an appropriate amount of ZN powder.

Phenomenon: If there is gas generated, there is sulfuric acid in the solution after the reaction.

zn+h2so4=znso4+h2(g)

Steps: Take the reaction solution and add ZN powder.

Phenomenon: No obvious phenomenon.

Conclusion: The sulfuric acid has been relied.

Bicarbonate and carbon dioxide do not react.

The phenomenon of continuous carbon dioxide into the clarified lime water is that the clarified lime water first becomes turbid and then clear.

The equation that becomes turbid first: CO2 + Ca(OH)2==CaCO3 +H2O and then becomes clear: CaCO3 + H2O + CO2==Ca(HCO3)2 There is no reaction equation for bicarbonate and carbon dioxide.

It is true that it cannot react, the phenomenon you said is that Mr. becomes calcium carbonate, and calcium carbonate reacts with CO2 to form calcium bicarbonate soluble, and if so, it becomes clear, which is the reaction of CO2 and carbonate.

The phenomenon of continuous introduction of carbon dioxide into the clarified lime water is that the clarified lime water becomes turbid first and then clear.

The equation that becomes turbidity first: CO2 + Ca(OH)2 = CaCO3 + H2O

The equation for clarification is CaCO3+H2O+CO2=Ca(HCO3)2

(1) A As the reaction progresses, the concentrated sulfuric acid gradually thins, and if there are bubbles when iron powder is added, it proves that there is sulfuric acid left.

30b-30a+9/v mol/l

I was going to write you the reaction equation on it, but... I'm too lazy. So I'll just write the results. I don't know if it's right to do it myself. Hey.

Then the water flows from the beaker to the gas collector

Because sulfur combustion consumes oxygen and produces SO2, which is absorbed by water, the pressure inside the gas collector cylinder decreases and is less than the outside atmospheric pressure, so the water flows into the gas collector cylinder through the conduit.

If you consider that SO2 dissolves in water, it is right to left, but sulfur combustion will release a lot of heat to expand the air, and the liquid level in the duct will be lowered, which do you see?

Water flows from the beaker to the gas collector cylinder, and the oxygen is consumed by combustion, and the pressure in the cylinder is less than the atmospheric pressure.

Solution: Right flows to left.

Doubt: The sulfur dioxide produced by the combustion of sulfur dissolves in water, which causes the air pressure on the left side to decrease, but I don't think it's clear whether its solubility can really make water flow through).