Safety in the laboratory ：練習問題

A chemical bottle bears a hazard warning symbol showing a skull and crossbones. What specific hazard does this symbol indicate?

A student is heating a liquid in a test tube over a Bunsen burner. Which of the following safety precautions is the most crucial to observe?

A student has finished an experiment and has 10 mL of unused distilled water left in a beaker. Why is it a fundamental laboratory rule to never pour unused chemicals or reagents back into their original bottles?

When conducting an experiment, why is it a fundamental safety rule never to return any unused chemical reagents back into their original container?

During a laboratory session, a student accidentally knocks over a reagent bottle, creating a small puddle of an unknown liquid on the floor. What should the student do first?

Why is it a crucial safety rule to never eat or drink inside a science laboratory?

In the laboratory, a sand bucket is used to extinguish small fires. State which two components of the fire triangle are primarily affected by pouring sand over a fire and explain how this action puts it out.

A chemical bottle displays a hazard symbol depicting a dead tree and a fish next to a body of water.
a) State the primary hazard represented by this symbol.
b) Explain why substances with this symbol must never be disposed of directly down standard laboratory sinks.

You are conducting an experiment in the school laboratory that involves heating a liquid in a test tube. You observe that your classmate is preparing to heat their liquid but is pointing the mouth of the test tube directly towards another student.

a) What immediate safety instruction should you give to your classmate?

b) Explain the potential hazard if your classmate does not follow this instruction during heating.

A student uses a Bunsen burner to heat a beaker of water. After five minutes, they notice a layer of black powder (soot) has formed on the bottom of the beaker.

a) Based on this observation, what was the position of the air hole (open or closed) during the heating process?

b) Identify the type of flame used and explain why the black soot was produced in terms of the combustion of the gas.

c) Suggest two reasons why the other type of flame (non-luminous) is more suitable for experiments involving high-temperature heating.