About the use of the graduated cylinder! How to use the graduated cylinder

Small. Because of the top-down view, it is actually less than 20mlThe second time I looked up, so it was actually more than 5mlSo it should be less than 15ml

Small, when looking down, the line of sight is slanted downward, there is actually no 20ml, and the upward gaze is more than 5ml, so pour out less than 15ml

Small. Let's assume that the top view or the top view are tilted at the same angle,,, first the top view, so there is no 20ml, we assume that it is 17ml; The back is looking up, so it should be more than 5ml, let's say 8ml; So the answer is obvious, it is less than 15ml.

The big one is smaller than it actually is when looking down, and the reading is larger than it actually is when looking up, so the result is big.

For the first time, the actual reading is less than 20ml

If you look up at the back, the actual reading is greater than 5ml, so the liquid here and there must be less than 15ml

Small. Looking down will see the number big, and looking up will see the number small.

So the actual number is smaller than 15.

The reading is tangent to the lowest level, so the first time I look down, the level is below the scale of 20 (you can draw the picture below, just 20 and 20).

The first time you see less than the actual one, then the water beam at the beginning is less than 20

The second one sees more than the actual one, so the second one is greater than 5

So the quantifiers are the same.

Numbers less than 20 - 5> actual pour volume.

And the number less than 20 is -5<15

So, the actual one is less than 15

(1) When using the graduated cylinder, it must be placed smoothly.

2) When reading, the line of sight should be kept level with the lowest part of the concave liquid level in the graduated cylinder, and the reading should not be looked up or down.

3) When measuring the liquid quantitatively, first pour the liquid into the graduated cylinder, and when there is 1ml and 2ml away from the scale, use the rubber head dropper to add until the engraving line.

(4) When measuring a certain amount of liquid, keep the viewpoint, engrave the line, and on a horizontal line at the lowest part of the concave liquid level. For the actual liquid reading, keep the viewpoint, the lowest part of the concave liquid level, the engraved line is on a horizontal line, if you look up, the reading is small, and the bottom view is large.

5) The graduated cylinder cannot be used to heat or measure the hot liquid, cannot be used as a reaction vessel, cannot dissolve or dilute the solution in the graduated cylinder, etc.

6) The specification of the graduated cylinder is equal to or slightly greater than the volume of the liquid measured, and cannot be less than the volume of the liquid.

When filling the liquid into the graduated cylinder, hold the graduated cylinder with your left hand so that the graduated cylinder is slightly tilted, and hold the reagent bottle in your right hand so that the mouth of the bottle is close to the mouth of the graduated cylinder, so that the liquid flows in slowly. After injecting the liquid, wait 1 2 minutes for the liquid attached to the inner wall to flow down, and then read the scale value. Otherwise, the value read out is too small.

Tachibana holds the graduated cylinder so that it is naturally vertical, keeping his line of sight level with the lowest part of the concave surface of the liquid in the graduated cylinder, and then reading the volume of the liquid taken. <

When filling the liquid into the graduated cylinder, hold the graduated cylinder with your left hand so that the graduated cylinder is slightly tilted, and hold the reagent bottle in your right hand so that the mouth of the bottle is close to the mouth of the graduated cylinder, so that the liquid flows in slowly. After injecting the liquid, wait 1 2 minutes for the liquid attached to the inner wall to flow down, and then read the scale value. Otherwise, the value read out is too small.

Hold the graduated cylinder so that it is naturally vertical, keep your line of sight level with the lowest part of the concave surface of the liquid in the graduated cylinder, and then read the volume of the liquid taken by Yuanchun Xu. Otherwise, the reading will be high or low. The scale of the graduated cylinder face refers to the volume at a temperature of 20 degrees Celsius.

As the temperature rises, the cylinder undergoes thermal expansion and the volume increases. It can be seen that the graduated cylinder cannot be heated, nor can it be used to measure overheated liquids, let alone carry out chemical reactions or prepare solutions in the graduated cylinder.

The correct way to read the graduated cylinder is: eye, scale mark, lowest part of the concave surface, and the three points are kept on the same horizontal line.

First, the process of measuring cylinder reading.

Before reading, when the liquid is injected into the graduated cylinder, generally do not read immediately, let the liquid attached to the inner wall of the graduated cylinder flow down and then read, otherwise the reading value will be small; In addition, when reading, head-up is the correct way to read.

2. Precautions for using graduated cylinders.

1. It cannot be used as a reaction vessel.

2. It cannot be heated. Graduated cylinders are glassware, and heating will deform them, which will affect their accuracy, especially repeated long-term heating and high-temperature heating.

3. It cannot dilute concentrated acid, concentrated alkali, especially corrosive liquids. Although glass is an inert material, it is not without a little activity, and certain strong acids and alkalis, especially strong alkalis, can still corrode it, so long-term storage or long-term use of graduated cylinders is also inaccurate.

4. Cannot store medicines. A graduated cylinder is a measuring device, not a container, and is not suitable for storing liquids.

5. The hot solution cannot be measured. If you measure a liquid that is too hot or too cold, it is not accurate.

6. Can not be cleaned with decontamination powder to avoid scratching the scale, the measuring cylinder is not allowed to be brushed, because brushing will wear the inner wall of the graduated cylinder, resulting in changes in the content volume of the graduated cylinder, and the code will affect the accuracy of the graduated cylinder.

7. Wash with a bend. Sometimes, after we finish pouring, we find that there are a lot of hanging walls in the graduated cylinder, and we feel that the amount poured is not enough, so we are using solvents or other means to moisten repeatedly. In fact, this is also wrong, because the design of the graduated cylinder was designed with the wall of the graduated cylinder in mind, and this part of the volume is taken into account, and the volume poured out is the volume we need.

1. The first step is to inject liquid into the graduated cylinder, hold the graduated cylinder with your left hunger and hand, and then hold the reagent bottle in your right hand, so that the mouth of the graduated cylinder is close to the mouth of the graduated cylinder, so that the liquid flows in slowly, and when the amount to be injected is slightly less than the required amount, put the graduated cylinder flat and use the rubber head instead.

2. The second step is reading, after injecting the liquid, put the graduated cylinder on a flat table and wait for 1 2 minutes to make the liquid attached to the inner wall flow down, and when observing the scale, keep the line of sight and the lowest part of the concave liquid surface of the liquid in the graduated cylinder at the same level, and then read out the volume of the liquid taken.

Graduation value of the graduated cylinder:

The scales on the outer wall are in ml, with a 10 ml cylinder representing ml per compartment and a 50 mL cylinder representing 1 mL per compartment. The larger the visible graduated cylinder, the thicker the diameter, the smaller the accuracy, and the greater the reading error caused by the deviation of the line of sight.

The graduated cylinder is a crude measuring device, and its family of eggplant is accurate. If the minimum scale of a graduated cylinder with a capacity of 5ml is, its accuracy is;

If the minimum scale of a graduated cylinder with a capacity of 10ml is, its accuracy is; A graduated cylinder with a capacity of 50 ml has a minimum scale of 1 ml, an accuracy of 1 ml, and so on. Common, more accurate graduated cylinders can only record a significant value to one decimal place, such as: Generally, no estimation is required.