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How to measure solid density in laboratory electronic balances

Date:2019-11-19

Electronic balances and density test assemblies are often used to measure solids density during material measurement and analysis in everyday laboratories.

Before performing density measurements, we need to do the following preparations:

1. Electronic balance. The accuracy of the electronic balance should be selected according to the specific requirements of the accuracy of the measured density data, and the capacity of the electronic balance should be selected according to the volume and weight of the sample to be tested. Before the test, it is necessary to preheat the prepared electronic balance for a long time and make necessary corrections to ensure the accuracy of the measurement data.

2. Test the components. It is necessary to select a suitable test component. For example, for some materials that are large in size and cannot be placed in the weighing chamber, the under-hook test component should be selected.

3. Sample to be tested. In order to measure the accuracy of the density in consideration of the influence of the surface tension of water, it is recommended that the weight of the sample to be measured be greater than 1 g. In order to improve the measurement accuracy, it is recommended to select a sample with a shape rule and a small surface roughness.

4. Select the appropriate auxiliary liquid. Generally available: water, alcohol, and others. When testing the auxiliary liquid, it is necessary to select according to the nature of the specific test sample. For example, if it is easy to react with water, alcohol can be selected as the auxiliary auxiliary liquid.

Electronic Weight Precision Balance

Once you have the equipment and samples you need, follow these steps:

1. Open the left or right side of the lab electronic balance and remove the weighing pan and insert the density bracket into the electronic balance.

2. Place the bracket in the appropriate position above the bracket to ensure that the bracket does not come into contact with the bracket.

3. Place the beaker in the center of the stand. The thermometer is inserted into the beaker to measure the current temperature of the liquid.

4. Inject a reference liquid of known density (usually water or alcohol) into the beaker to ensure that the solid to be tested can be completely immersed by the liquid more than 1 cm.

5. Place the hanging basket on the fixing bracket to ensure that there is no air bubble on the surface and does not touch the beaker or thermometer.

6. Turn on the electronic balance switch

7. Close the windshield and remove the tare weight;

8. Open the electronic balance windshield and place the measured solid on the weighing arm of the fixed bracket or the weighing pan at the top of the hanging basket; if the mass of the measured solid in the air is greater than 20g, place it on the top of the hanging basket. Weighing in the weighing pan;

Note: For solids with a density less than the auxiliary liquid density, the weighing net at the bottom of the hanging basket should be reversed to press the object under test. If the buoyancy of the solid is greater than the weight of the hanging basket, the weighing must be assisted by placing an additional weight on top of the hanging basket. After loading the additional stainless steel weights, the electronic balance is peeled and the weighing is started again.

9. Turn off the electronic balance windproof, after the electronic balance is stable, the electronic balance will automatically record the weighing result A;

10. Open the electronic balance windproof door, remove the solid to be tested, close the windproof door and remove the tare weight;

11. Open the electronic balance and open the door to place the measured solid in the weighing net at the bottom of the hanging basket, and ensure that no bubbles adhere to the solid surface (the surface bubbles can be removed with a small brush);

12. Close the electronic balance windscreen. After the electronic balance is stable, the electronic balance will automatically record the weighing result B. And calculate the density of the solid to be tested according to the density formula.