In chemical experiments, if the dosage is not stated, how much is generally taken

1.Take 1-2ml for liquids and 2-3 grams for solids.

2.The temperature will not be verified, and the product is covered with a cold beaker above the candle, and then a cold beaker dipped in clarified lime water, the cold beaker has water droplets, and the beaker stained with clarified lime water becomes cloudy, indicating that the burning products of the candle have water and carbon dioxide.

3.Flammable gases.

4.Do not put the original reagent bottle back, but pour it into the designated place.

5.No more than 1 3 of the volume of the test tube, the inclination angle is 45 degrees, the mouth of the test tube can not be facing people, and the preheating should put the test tube on the outer flame of the flame several times.

6.Quenching and heating, no preheating of test tubes, no heating on the outer flame when heating.

1.Liquid 2-5 ml

Solids are one teaspoon.

Gases are generally not considered.

2.I don't know the temperature, but I can see what can and can't burn based on the ignition point of the object. The combustion product is the same as the test of water and carbon dioxide.

3.I don't know.

4.The leftover drugs used in chemical experiments should not be thrown away at will, but should be handed over to a teacher or placed in a designated place.

The length of the tube, 45 degrees - 60 degrees.

6.Put it in cold water, add cold water, and accidentally knock the test tube by yourself.

1 Question as above Solids: just spread on the bottom of the tube Liquid: 2-3ml

2** Candle flame temperature and test candle combustion products (operation steps, experimental phenomena, experimental conclusions. A sentence or two is all it takes! )

Temperature: Horizontal flame with a small wooden stick The phenomenon is that the outside turns black Conclusion The outer flame temperature is high.

Product: A dry, cold beaker over the flame Water mist is generated Remove Quickly pour in clarified lime water Clarified lime water becomes cloudy Evidence of water vapor and carbon dioxide formation.

3. What is the composition of white smoke that can be ignited after the candle is extinguished? It's paraffin steam.

4. What can I do with the leftover drugs in chemical experiments? What should it be? It cannot be put back into the original reagent bottle, discarded, etc., and should be processed centrally.

5. What is the maximum amount of liquid to be taken when heating the liquid in the test tube? What is the angle of inclination of the tube? How do I warm up? The amount does not exceed 1 3 of the tube with an inclination of 45°

Hold the tube with a clamp and move slowly above the flame so that the reagents in the tube are evenly heated.

6What are the possible causes of the explosion of the test tube when the liquid in the test tube is heated? (three).

Didn't preheat Suddenly cooled down Didn't heat with an external flame.

Are you satisfied with this?

Our teachers have talked about this.

Hope it helps.

Hello, glad to answer for you! The preheating of the balance is generally 30min1The leveling of the balance, the pallet balance is to adjust the pointer, and the electronic balance is to adjust the bubbles.

2。Correction of weights. Use a balance around the maximum range of the balance to calibrate the balance.

At the same time, the zero point 3 is corrected. Weigh the noisy luck. The weighing of items in the chemical laboratory should not allow the drug to touch the tray of the balance directly, and the weighing paper can be weighed with closed weighing paper, but care should be taken to peel 4.

When weighing, add a small amount when approaching the required weight, hold the medicine spoon in one hand, and gently pat the wrist holding the medicine spoon with the other hand, so that the medicine is added in a small amount until the end, if there is too much medicine, do not put it back into the reagent bottle. 5。The reading of the balance beam must be read after the reading is stable, because sometimes the balance will have a reaction time, and you can't be too anxious.

6。Shutdown. Everything needs to be put back in place and cleaned, the balance should not be moved, the tray should not be pressed too hard, and the cover should be closed.

During the experiment, pay attention to saving drugs, if the dosage is not specified, you should take the minimum amount, that is, 1 2ml of liquid, and the solid only needs to cover the bottom of the test tube;

Therefore, the answer is: the maximum number of pants disturbs a small amount to cover the bottom of the test tube can be eliminated.

In order to save drugs, according to the rules for the use of drugs in the real laboratory: when taking chemicals, if the dosage is not specified, the liquid should generally be taken in a small amount (1-2 ml), and the solid only needs to cover the bottom of the test tube

So the answer is: Bu Zheng stupid dropper; 1～2．

1. 2-3ml of liquid, cover the bottom of the test tube with solid, and put it in a special instrument to prevent the drug from being contaminated.

2. Paper trough is used for powder solids, and tweezers are used for bulk solids.

3. Inverted. 4. The test tube does not exceed 1 3

5. Outer flame, inner flame, flame heart.

6. The lowest part of the concave liquid level.

7. Nitrogen 78%, oxygen 21%, noble gas, carbon dioxide, other gases.

Take a good look at your first chemistry book.

In order to save drugs, according to the rules for the use of laboratory drugs: when taking chemicals, if the dosage is not specified, the minimum dosage should be taken The liquid is usually 1 2ml, and the solid only needs to cover the bottom of the test tube

So the answer is: 1 2;Cover the bottom of the tube

In order to save drugs, according to the principle of laboratory drug access, when taking chemicals, if the experiment does not specify the dosage, the liquid should generally be taken according to the minimum amount (1 2ml), and the solid only needs to cover the bottom of the test tube The remaining drugs in the experiment can neither be put back into the original bottle, nor can they be discarded at will, let alone taken out of the laboratory, and should be placed in the designated container

So the answer is: 1 2ml; Cover the bottom of the tubePlace in the designated container

In order to save drugs, according to the rules for the use of laboratory drugs: when taking chemicals, if the dosage is not specified, the liquid should generally be taken according to the minimum amount (1 2ml), and the solid only needs to cover the bottom of the test tube

So the answer is: 1 2;Cover the bottom of the tube

In order to save drugs, if the dosage is not specified, the minimum amount of liquid should be taken 1-2ml, and the solid can be covered with the bottom of the test tube, if the amount is less, it will affect the experimental results

Do not touch the medicine with your hands, do not put your nose to the mouth of the container to smell the smell of the medicine (especially gas), and do not taste the taste of any medicine;

The principle of "three noes" for the remaining drugs: the remaining drugs during the experiment cannot be put back into the original bottle; Don't throw it away; Don't even take out the lab

So the answer is: 1 2ml; Cover the bottom of the tubeTouching with hands; Sniff the mouth of the container with your nose; Taste any; Put back in the original bottle; Discard; Take out the lab