The laboratory

Match each piece of lab equipment with its use:

1. a) Measuring cylinder
2. b) Thermometer
3. c) Balance

1) Measuring the temperature of water.

2) Measuring a volume of liquid fairly accurately.

3) Measuring the mass of a solid.

You need to measure exactly $25\ \text{mL}$ of water for an experiment. The three containers are shown in the figure:

Which piece of apparatus would you use: a beaker, a measuring cylinder or a conical flask? Justify your choice.

The conical flask is wide at the base and narrow at the neck, as shown in the figure.

Explain what advantage this shape has when swirling a mixture.

Before entering the laboratory, the teacher requires everyone to put on a lab coat and, for some practicals, safety goggles as well. Explain what each protects against.

In the laboratory, it is forbidden to taste any substance, even if it looks like water.

1. a) If you need to smell a chemical, how is it done safely?
2. b) Why do you think this rule exists?

At the next desk, Unai is dipping a biscuit into a beaker of water while his lab partner, who has long loose hair, leans over a lit Bunsen burner. Point out the two safety mistakes and write down the rule that corrects each one.

On the label of some alcohol you see a pictogram with a flame, and on another chemical, a skull and crossbones. Observe the two pictograms:

1. a) What hazard does each pictogram indicate?
2. b) What precaution would you take with each chemical?

What is the Bunsen burner used for in the laboratory? Write down two safety rules that must always be followed when using it.

You must heat $50\ \text{mL}$ of salty water to $40\ ^\circ\text{C}$ and measure the temperature while it heats up. Write down the complete procedure: the required equipment, the steps in order, and the safety rules you apply at each stage, justifying at least two of them.

You drop a test tube on the floor and it breaks. State two things you should do immediately and one thing you must never do.

You are going to heat $100\ \text{mL}$ of water and want to record its temperature every minute.

1. a) Make a list of the equipment you need (at least four items).
2. b) Write, in order, the steps you will follow.

Observe this laboratory scene: Carla is working with loose hair, she has left her sandwich on the bench, the Bunsen burner is lit while unattended, a classmate tastes a liquid "because it looks like lemonade", and there are sheets of paper right next to the flame. Find the five safety mistakes and write down the rule that corrects each one.