Precautions for Using Test Tubes

发布时间：2023-06-05

　　(1) When filling the test tube with a solution, do not exceed one-half of its capacity; when heating, do not exceed one-third of its capacity.

　　(2) When adding liquid to a test tube with a dropper, the dropper should be held above the tube and not inserted into the mouth of the tube.

　　(3) To transfer a solid sample in chunk form, use forceps to pick it up and place it at the mouth of the test tube; then slowly raise the tube to allow the solid to slide down into the bottom. Do not let the solid fall directly, as this could cause the bottom of the test tube to crack.

　　(4) When heating, use a test tube holder, and ensure the mouth of the test tube does not face anyone. When heating a test tube containing a solid, point the opening slightly downward; when heating a liquid, tilt the test tube at approximately 45°.

　　(5) Heat evenly to prevent bumping or breakage of the test tube.

　　(6) Do not subject to sudden cooling after heating to prevent cracking.

　　(7) Preheat the test tube before heating to prevent it from cracking due to sudden temperature changes.

　　(8) When heating, ensure that no water droplets remain on the outer surface of the test tube to prevent uneven heating and subsequent breakage.

　　(9) After heating, do not wash the test tube until it has cooled to room temperature.

　　(10) When using a test tube clamp to hold a test tube, slide the clamp over the tube from the bottom upward and secure it in the upper-middle portion. If the test tube is divided into three equal parts, the clamp should be positioned within the one-third section closest to the tube’s opening.

　　(11) Heat the substance using the outer flame.