Test tube is a common instrument in chemistry laboratory, which is used as a reaction container for a small amount of reagents. They should be preheated at room temperature or when heated, otherwise the test tube will burst easily. ) use. Test tubes are divided into ordinary test tubes, supporting test tubes and centrifugal test tubes. The specifications of ordinary test tubes are expressed in terms of outside diameter (mm)× length (mm), such as 15× 150, 18× 180, 20×200, etc.
Test tubes are divided into ordinary test tubes, supporting test tubes and centrifugal test tubes.
The specifications of ordinary test tubes are expressed in terms of outside diameter (mm)× length (mm), such as 15× 150, 18× 180, 20×200, etc. Centrifugal tubes are expressed in milliliters.
Material: glass.
(1) The flat-ended test tube is a round-bottomed flat-ended glass tube, and the nozzle is melted. The flat mouth is convenient for disinfection and sterilization at the nozzle.
(2) The rolled-mouth test tube is a round-bottomed glass tube with a rolled edge (or round mouth) at the nozzle. The roll mouth (or round mouth) is used to increase the mechanical strength, and at the same time it is convenient to clamp and not easy to fall off.
(3) The fermentation test tube is a short tube (6mm in diameter and 30mm in length) with a round flat mouth.
(4) The branch test tube is a flat-mouth test tube with a side branch pipe, and the side branch pipe is mainly used to connect with the exhaust pipe, and the nozzle is inserted into the filter funnel with a perforated rubber plug to replace the microfiltration bottle as the receiving bottle for microfiltration. Calibrated test tube: a round-mouth test tube. The pipe body is engraved with capacity scale markings, which can directly read the measurement figures and is convenient to use.
(1) Take liquid or solid reagent.
② Heat a small amount of solid or liquid.
(3) a reactor for generate a small amount of gas.
(4) Collect a small amount of gas.
(5) Dissolve a small amount of gas, liquid or solid solute.
(6) As a container in the process of centrifugation.
(7) Used as a reaction container for a small amount of reagents, used at normal temperature or when heating.
How to use test tubes:
(1) When filling solution, it shall not exceed 1/2 of the test tube capacity, and when heating, it shall not exceed 1/3 of the test tube capacity.
(2) When dropping liquid into the test tube with a dropper, the dropper shall be suspended and shall not extend into the mouth of the test tube.
(3) Put the massive solid into the mouth of the test tube with tweezers, and then slowly erect the test tube to make the solid slide into the bottom of the test tube to prevent the solid from falling directly and the bottom of the test tube from breaking.
(4) Use a test tube clamp for heating, and the test tube mouth cannot be pointed at people. When heating the test tube filled with solid, the nozzle is slightly downward, and when heating the liquid, it is inclined by about π/4 radian.
(5) Heat evenly to avoid boiling or tube explosion.
(6) It cannot be quenched after heating to prevent cracking.
(7) Preheat when heating to prevent the test tube from bursting due to sudden heating.
(8) When heating, keep the outer wall of the test tube free of water drops to prevent it from bursting due to uneven heating.
(9) After heating, it is not allowed to rinse the test tube without cooling to room temperature.
(10) When using a tube clamp to clamp a tube, put the tube clamp upward from the bottom of the tube and clamp it in the middle and upper part of the tube. If the length of the test tube is divided into three parts, it is reasonable to clamp the test tube within one third of the end near the test tube mouth.
(1 1) The external flame of alcohol lamp or alcohol blowtorch should be used when heating.
In stressed relatively open syllables, the vowel letter U is pronounced with the long vowel /ju/. For example:
Tune tune
Dumb, silent
naked
Mule. Mule.
Cubic cube
Huge, huge
Test tube
Duke. Duke
I hope I can help you solve your doubts.