Final answer:
When heating a substance in a test tube, the open end should be pointed away from all people for safety. Other precautions include working in a well-ventilated area, not leaving flames unattended, and handling hot equipment with care to maintain a safe laboratory environment.
Step-by-step explanation:
When heating a substance in a test tube, safety precautions are paramount to prevent accidents. The open end of the test tube should always be pointed away from all people. This precaution is taken to ensure that if any splattering or unexpected reactions occur, the contents will not be directed towards yourself, your classmates, or your lab partner. Additional safety measures include using your hand to gently waft (fan) the vapors towards you instead of directly smelling them, working in a well-ventilated room, not leaving flames unattended, and not smelling, tasting, or touching chemicals unless instructed. Moreover, tie back loose hair and clothing when using an open flame, be cautious handling hot equipment like beakers, and never reach across flames or heat plates carelessly.
These measures are not just good practice—they are essential for maintaining a safe laboratory environment and should be followed in every experiment involving heat and chemicals. Remember to follow all instructions given by your teacher, especially regarding the handling of flammable chemicals and the location of fire safety equipment.