What are the weighing methods of analytical balance?

What are the weighing methods of analytical balance? The analytical balance is no longer unfamiliar to us It is an indispensable weighing instrument in quantitative analysis It is a more powerful weighing instrument than the platform scale, which can weigh to more than 0.0001g (0.1mg) There are many kinds of them, such as mechanical analytical balance, electronic analytical balance, manual analytical balance, semi-automatic analytical balance and so on So, do you know the weighing method of analytical balance? Let's briefly talk about the weighing methods of analytical balance? At present, there are three weighing methods of analytical balance: direct weighing method, decrement method and designated method Direct weighing method: if the said solid sample has no hygroscopicity and is stable in the air, the direct weighing method can be used First, accurately weigh the mass of the clean container on the balance, then use the spoon to take a proper amount of sample and add it into the container, and weigh the total mass The mass of the sample is obtained by subtracting the values of the two masses Decrement method: the decrement method is generally used for weighing on the analytical balance First weigh out the mass of the sample and the weighing bottle, then pour some of the sample in the weighing bottle into the container of the medicine to be filled, until the estimated quantity is close to the required quantity The analytical balance is poured into the back cover of the medicine and the weighing bottle is put on the balance to weigh its mass The difference between the two masses is the mass of the sample If too much medicine is poured into the container at one time, it must be discarded and weighed again Do not put it back into the weighing bottle If the poured sample is not enough, it can be added again, but the times should be less Designated method: for the samples with stable properties, sometimes for the convenience of calculation, the samples of designated quality can be weighed When weighing with the specified method, place a watch glass on both sides of the balance pan (their mass shall be as close as possible), adjust the balance point of the balance to about the middle scale, then add a fixed mass weight to the left balance pan, and add a sample to the right balance pan (it is convenient to take and place the sample) until the balance point of the balance reaches the original value At this time, the mass of the sample is Specified quality The above is the weighing method of analytical balance You can make a preliminary understanding In addition, when using the analytical balance for the first time, you should check whether the analytical balance is in a horizontal position and whether the power supply voltage matches After weighing, you should remove the weighing bottle (paper), close the side door and cut off the power supply Pay more attention to details at ordinary times, and the service life of analytical balance is also extended.