Laboratory test tubes can be directly heated. The specifications of test tubes are: test tubes are divided into ordinary test tubes, branched test tubes, centrifugal test tubes, etc.
Correct use of test tubes:
1. Using tweezers, place the solid block into the test tube. Do not drop solids directly into the test tube to prevent the bottom of the test tube from breaking;
2. Do not exceed 1/2 of the capacity of the test tube when filling the solution, and do not exceed 1/3 of the capacity of the test tube when heating.
3. When the liquid is dropped into the test tube with the dropper, it cannot reach the mouth of the test tube;
4. When clamping the test tube with the test tube clamp, remove the test tube clamp from the test tube.
6. Do not quench after heating to prevent cracking.
7. Preheat when heating to prevent the test tube from being suddenly heated and bursting.
8. When heating, keep the outer wall of the test tube free of water droplets to prevent it from bursting due to uneven heating.
9. Do not wash the test tube before cooling to room temperature after heating.
10. Use a test tube clamp to heat, and the test tube mouth should not face people. When heating a test tube containing solids, the nozzle of the test tube should be slightly downward, and the liquid should be inclined at about 45° when heating the liquid; the test tube clamp should be clamped at 1/3 of the bottle mouth.
11. Heat evenly to avoid bumping or bursting of the test tube;