How to measure the mass of an object with a balance: put, pick, weigh and remember.

the pallet balance is an instrument used to weigh the quality of substances in the laboratory. Each balance has a matching weight box. The smallest weight is 1g, and the pieces with a mass less than 1g are pieces, including 1mg, 2mg and 5mg. Some pallet balances only have more than 5 grams of silicon code, and when weighing less than 5 grams, the method of moving the weight is used. Before using the pallet balance to weigh substances, the pallet balance with wandering code should first put the wandering code at the zero of the scale, and then check whether the swing of the balance is balanced. If the balance is balanced, the pointer is in the middle (zero) of the scale at rest, and the number of squares swinging on the left and right sides of the scale is nearly equal when swinging. If the balance is not balanced, you can adjust the nuts under the left and right trays to achieve balance when swinging. When weighing, the weighed items are placed on the left plate and the weights are placed on the right plate. First, the weights with large mass are added, then the weights with small mass are added, and finally the pieces are added (mobile yards). Tweezers should be used to take weights. When weighing a substance with a specified mass, first put the weight and piece code (or wandering code) of this mass on the left plate, and then add the weighed substance to the right plate. When the mass of the weighed substance is close to the required mass, you can hold the medicine spoon in your left hand, pat your left hand with your right hand, and use the method of vibrating the medicine spoon to make a small amount of substance fall down to the balance. In order to prevent the corrosion and pollution of chemicals on the tray, drugs can not be directly weighed on the tray, but can be put into containers such as beakers, evaporating dishes and watch glasses. Paper can also be used. Before weighing, put a piece of clean paper with similar quality on each tray. After weighing, the mass number of the weighed object should be recorded in time. After weighing, put the weight and tweezers back into the weight box, and move the weight back to zero.