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Introduction to Laboratory Practice

8 min read

Working safely in the laboratory

A laboratory is where we test ideas. It can also be dangerous if rules are ignored. Good laboratory practice protects you, your classmates and your results.

Safety rules
RuleWhy
Listen to your teacher and follow the instructionsExperiments can be dangerous if done in the wrong order
Do not eat, drink or run in the laboratoryChemicals and breakages can harm you
Tie back long hair and wear protective clothingHair and loose sleeves catch fire or knock things over
Never taste or sniff unknown substances directlyThey may be poisonous
Report every spill, breakage or injury at onceA small problem can become a big one
Wash your hands and clear up at the endRemoves harmful substances
Laboratory hazard symbolsFive red diamond hazard symbols: flammable with a flame, corrosive with a drop eating a surface, harmful with an exclamation mark, toxic with a skull and crossbones, and explosive with a burst.FlammableCorrosiveHarmful / irritantToxicExplosive
Hazard symbols on chemical bottles: learn what each one warns about before you open a container.

Common apparatus

ApparatusUsed for
Metre rule / tapemeasuring length
Beakerholding and heating liquids
Measuring cylindermeasuring the volume of a liquid
Stopwatchmeasuring time
Spring balancemeasuring force (weight)
Thermometermeasuring temperature
Tripod stand and gauzesupporting things over a flame
Common laboratory apparatusTen pieces of laboratory apparatus drawn side by side: beaker, conical flask, test tube, measuring cylinder, burette, pipette, Bunsen burner, tripod and gauze, thermometer and retort stand.BeakerConical flaskTest tubeMeasuring cylinderBurettePipetteBunsen burnerTripod and gauzeThermometerRetort stand
Always read a scale with your eye directly above the mark. Reading from the side gives a wrong value (parallax error).
Parallax errorA pointer above a ruler. Viewed from directly above, the pointer reads the correct value. Viewed from the left or right, it seems to point at a different mark, which is parallax error.correct: eye directly abovewrongwrongLook straight down at the scale.
Try itPractise reading a thermometer

Move the slider to change the temperature. Read the scale and then check with the number. Good readers look at the top of the liquid thread at eye level.

Worked exampleWriting a good practical report

What should a report on an experiment contain?

  1. Title and aim: what you wanted to find out.
  2. Apparatus and method: what you used and what you did, in order.
  3. Results: measurements in a table, with units.
  4. Conclusion: what the results show, and any sources of error.

Answer: Title and aim, apparatus, method, results (with units) and a conclusion.

Check yourself What should you do first if you break a glass beaker?
Check yourself Which apparatus measures the volume of a liquid most accurately?

Key terms

Apparatus
The equipment used in an experiment.
Parallax error
A reading mistake caused by looking at a scale from an angle.
First aid
Immediate help given to an injured person.

Summary

  • Follow safety rules and know where the first-aid box and exits are.
  • Choose the right apparatus for each measurement.
  • Read scales at eye level to avoid parallax error.
  • A report has aim, method, results and conclusion.
Introduction to Physics Measurement