Analyze why the horizontal position of the balance is adjusted before weighing the balance

Ensure that the weighed is the mass of the object, and if it is not level, the weight cannot be guaranteed to be the mass of the object.

How to use the pallet balance: (1) To be placed in a horizontal place. The game code should be reset to zero.

2) Adjust the balance nut (nuts at both ends of the balance) to adjust the zero point until the finger is aligned with the ** scale mark. (3) Put the weighing object on the left tray, and put the weight on the right tray (the right yard of the left object). According to the properties of the weighed object, it should be placed on glassware or clean paper, and the mass of the glassware or paper piece should be weighed on the same balance in advance, and then the substance to be weighed should be weighed.

4) Add weights from the maximum value of the estimated weighing object and gradually decrease. Pallet balances can only be weighed to the gram. Add or subtract weights and move the yard on the ruler until the pointer is aligned with the tick mark again.

5) Objects that are too cold or too hot should not be weighed on the balance. It should be weighed (or weighed in a special vessel) after being placed in a desiccator at room temperature. 6) The mass of the object = weight of the weight + the degree displayed by the code (7) The weight must be handled gently with tweezers, and the weight should be placed in the weight box, and after weighing, the code should be moved back to the zero point.

8) When weighing dry solid medicines, a piece of paper of the same quality should be placed on each of the two trays, and then the medicine should be weighed on the paper. (9) Drugs that are easy to deliquescent must be weighed in glassware (such as small beakers, surface dishes).

10) If the weight is rusty, the measurement result is small; If the weight is worn, the measurement result is too large.

The analytical balance has no effect on the weighing at the level.

Electronic scales. Weighing things, weighing uneven symmetrical weight has an effect. Because the electronic scale measures the weight of the object through the sensor, and the sensor is inside the electronic scale, if the four legs of the electronic scale are unevenly stressed, it will lead to the error of the sensor of the electronic scale.

The accuracy of the scale.

It is not allowed to be flattened or not. Put the electronic scale on the flat ground and weigh it, the horizontal beads of the scale are balanced, and the result is basically accurate; However, if a piece of plastic foam is added on one side of the scale, the horizontal beads in the scale are tilted, and the result of the measurement is a small amount of catties.

Basic principle. Balances are commonly used instruments in laboratories. A balance is a weighing instrument, which is an instrument that measures the mass of an object. It is based on the principle of leverage.

It is made with a small plate at each end of the lever, a weight is placed at one end, and the object to be weighed is placed at the other end, and the lever ** is equipped with a pointer, and when the two ends are balanced, the mass (weight) of both ends is equal. These truths are already common to those who have studied physics. Modern balances are becoming more and more sophisticated, more and more sensitive, and there are more and more types.

The above content reference: Encyclopedia - Balance.

Adjustments to be made to the balance before using the balance to measure:

1.Adjust the horizontal placement of the balance base;

2.Adjust the scale of the balance back to zero;

3.Adjust the balance nut of the balance to balance the beams of the balance;

Attention should be paid to when using or empty shortening:

1.The measured object is placed on the left disk, and the weight is placed on the right disk;

2.with tweezers.

Add or subtract weights, handle them gently, and in order from largest to smallest;

3.Keep the balance clean and dry, and the chemicals cannot be placed directly on the weighing pan;

4.When moving the code, the mass of the object measured by the shirt and pants is equal to the mass of the weight plus the number of the code;

5.After the measurement is completed, the experimental equipment should be sorted out and put back in place.

The method of weighing the modulus of the analytical balance is as follows:

1. Direct weighing method. According to the industry, direct weighing can be used if the solid specimen being weighed is not hygroscopic and stable in air. The specific operation is to accurately weigh the mass of the clean container on the balance, and then take an appropriate amount of sample with a medicine spoon and add it to the container to weigh its total mass.

By subtracting the values of the two masses, the mass of the specimen can be obtained.

Second, the reduction method. It is understood that the reduction method is a commonly used method for analyzing balance weighing.

The specific operation is to first weigh the exact mass of the sample and the weighing flask, and then pour a part of the sample in the weighing flask into the container to be filled with the drug until the estimated quantity is close to the amount sought. After the balance is poured, the weighing flask is covered, and the weight is accurately weighed on the balance. The difference between the two masses is the mass of the specimen.

It is worth noting that when weighing by the reduction method, if too much drug is poured into the container in a short-code manner, the re-weighing must be discarded and the weighing bottle cannot be put back. If a lot of medicine is poured, it can be added again, but the number of times should be small.

3. This weighing method is suitable for tests with relatively stable properties and is convenient for calculation.

The specific operation is to put a surface dish on each side of the balance plate (their mass is as close as possible), adjust the balance point of the balance around the middle scale, and then add a fixed quality weight in the left balance plate, and add a test block coarse sample in the right balance plate (so that it is more convenient to take and place the sample), until the balance point of the balance reaches the original value.

Adjust the height of the first two feet so that the air bubbles in the level are on the scale circle** and the balance is level.

Generally, there are three feet at the bottom of the analytical balance, the back foot is fixed, and the first two feet are adjustable. By adjusting the height of the first two feet, the air bubbles in the level can be brought to the scale ring**, so that the balance is level.

Rotating a left or right leveling base alone is actually adjusting the tilt of the balance, and it will definitely adjust the level bubble to the ** line. The key is which leveling base. It can be judged in this way, first manually tilt the balance to make the level bubble reach the ** line, and then look at the leveling base, which one is high, or low, adjust the height of one of the leveling bases, you can make the level bubble move to the ** line.

Before weighing, check whether the balance is normal, whether it is in a horizontal position, whether the lifting lugs and ring code fall off, and whether the inside and outside of the glass frame are clean. Analytical balances are indispensable and important instruments for quantitative analysis, generally referring to balances that can accurately weigh to the grams (milligrams).

Precautions: 1) The action should be slow and light: the lifting pivot is slowly opened and opened to the maximum position, and the ring code is slowly rotated to prevent the ring code from falling off or misaligned.

2) The weighing object can not be placed directly in the weighing tray, according to the different properties of the weighing object, it can be placed in the paper, surface dish or weighing bottle. Objects that do not exceed the maximum planting weight of the balance cannot be weighed.

3) The balance cannot be replaced in the same weighing process, so as to avoid relative error.

How to use an electronic analytical balance:

1 Check and adjust the balance to a horizontal position.

2. Check whether the power supply voltage matches in advance (configure a voltage regulator if necessary), and preheat it up to the required time according to the requirements of the instrument.

3 Turn on the balance switch after sufficient warm-up time, and the balance will automatically adjust the sensitivity and zero point. After the stability mark is displayed, the formal weighing can be carried out.

4 When weighing, put the clean weighing flask or weighing paper on the weighing pan, close the side door, press the peel button lightly, the balance will automatically calibrate the zero point, and then gradually add the substance to be weighed until the required weight.

5 The weight of the substance to be weighed is the actual value displayed on the display when the " " symbol appears in the lower left corner of the display.

6. At the end of weighing, the weighing bottle (paper) should be removed in time, the side door should be closed, the power supply should be cut off, and the use should be registered.

How to use a mechanical analytical balance:

1.Slowly turn the lifting pivot knob to open the balance and observe the swing range of the pointer, if the pointer swings to one side, you can adjust the zero adjustment screw on the balance beam.

2.Put the substance to be weighed from the left door into the left plate**, according to the initial weight weighed on the tray balance first, use tweezers to clamp the appropriate weight from the right door into the right plate**, and slowly lift the pivot button half-literally with the left hand (when the mass difference between the two sides of the balance is too large, the full-lift lifting pivot button may cause the lifting lug to fall off.) damage the blade), depending on the deviation of the pointer, increase or decrease the weight.

After the gram weight is tested, add the game code to adjust. In the process of adjusting the balance of the game, the right door must be closed, then the lifting pivot button can be raised, and after the pointer swing stops, the scale pointed on the sign should be at or near the zero point.