Practice experiments for weighing operations
Practice experiments for weighing operations
The experimental objectives of this experiment are: 1. to familiarize with the structure and performance of the rack-and-pan balance and electronic balance, and to master the use of the two kinds of balances and the precautions to be taken in the weighing operation; 2. to master the use of various kinds of measuring instruments and the method of measuring liquids of less than 1 ml.
Operation method
weighing method
Materials and Instruments
Shelf Pan Balance Electronic Balance Move 1. weighing operations to weigh the following medications: Caveat 1. When using measuring cylinders and cups, they should be held vertically, with the eyes level with the desired scale, and the reading should be based on the concave surface of the liquid. The general operating position of the small measuring device is to use the left thumb and forefinger to hold the lower part of the measuring device vertically and smoothly and with the middle finger pad at the bottom. Right hand bottle pouring liquid, the bottle must be up or to the sides, the bottle cap can be clamped between the little finger and ring finger, pouring immediately after the cover, put back to the original place. 2. The liquid should be injected into the measuring device, the mouth of the bottle should be close to the edge of the measuring device, along the inner wall of the injection, in order to prevent the liquid from spilling out of the device. Measurement of viscous liquids such as glycerin, syrup, etc., whether in the injection or pouring out, must be sufficient time to make it flow according to the scale to ensure the accuracy of the volume. 3. Measured measure, need to be washed and drained before measuring other liquids, if necessary, also need to be dried and then used. 4. When measuring certain solutions or tinctures with a dosage of less than 1 ml, the unit of measurement should be a drop. If there is no standard burette, the ordinary burette can be used, that is, the first burette to determine the number of drops of 1 ml of liquid measured, and then converted to the number of drops required. 5. When weighing drugs, keep the cap in your hand, hold the cap with your left thumb and forefinger, the neck of the bottle with your middle finger and ring finger, and the crooked spoon with your right hand. 6. according to the nature of the drug being weighed, choose the weighing paper or appropriate container. Choose a balance according to the weight of the drug being weighed. Generally, a torsion balance can be used for weighing drugs of less than 1 g and more than 0.1 g in weight. For more product details, please visit Aladdin Scientific website.
Sodium bicarbonate Potassium iodide Vaseline Liquid paraffin Iodine Purified water Ethanol Glycerin
Crooked spoon Weighing paper
2. measuring operation to measure the following drugs:
Two persons in the same group check with each other that the balance chosen, the measuring device is correct and that the operation is done correctly.