Precautions for the use of glass reagent bottles
1. Glass instruments that can be heated include test tubes, beakers, flasks (round-bottom flasks, flat-bottom flasks), distillation flasks (round-bottom flasks, flat-bottom flasks), and conical flasks.
2. It cannot be directly heated with an alcohol lamp, and the glass instruments that can be heated after the asbestos mesh is placed are beakers, flasks (round-bottomed flasks, flat-bottomed flasks), distillation flasks (round-bottomed distillation flasks, flat-bottomed distillation flasks), conical flasks .
3. Glass instruments such as Kip generators, gas cylinders, watch dishes, and drying tubes cannot be heated during use, but chemical reactions can be carried out in these instruments without heating.
4. Glass instruments that cannot be heated or chemically reacted in use include: plastic dropper, separatory funnel, long-necked funnel, water tank, graduated cylinder, acid burette, basic burette, desiccator, reagent bottle , drip bottle, condenser tube.
measuring cup
A measuring cup is a measure-out (symbol Ex) measure that is used to measure the volume of liquid expelled from the measure. The volume of liquid discharged is the number of volumes read from the scale value while the liquid is in the gauge. There are 2 types of measuring cups. When facing the indexing table, the pouring spout of the measuring cup is to the right, which is convenient for left-hand operation, which is called the left-hand measuring cup. With the pouring spout to the left, it is called a right-hand measuring cup. Measuring cups less than 250mL are left-handed, and those over 500mL are right-handed. The graduation of the measuring cup is uneven, the upper is dense and the lower is sparse, the large volume value is engraved on the top, and the low mark is the large volume value, and there is no zero scale. It is an instrument with poor precision among the measuring instruments. Its specifications are distinguished by volume, and 20mL and 250mL are commonly used.
Precautions for use
(1) The measuring liquid should be carried out at room temperature. When reading, the line of sight should be tangent to the bottom of the liquid meniscus.
(2) The measuring cup cannot be heated, nor can it contain hot solution, so as not to burst.
(3) When the substance is dissolved, its thermal effect is not large, it can be directly put into the measuring cup to prepare the solution.
Graduated cylinder
There are two types of measuring cylinders, with or without stopper and with stopper, and the quantitative methods are divided into two types: component-out type and measure-in type (symbol In). Drop-in gauges are used to measure the volume of liquid injected into the gauge. When the liquid is in the measuring device, its volume is the value directly read from the indexing table of the measuring device, and the plugged measuring cylinder is only the measuring type. There are two dosing methods for unplugged graduated cylinders.