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Drawing practical apparatus diagrams

Apparatus diagrams (Paper 3): draw clear line diagrams, correct labels, and correct positions (e.g., thermometer bulb) and explain how the arrangement makes the method work.

  • SEC G3 Pure Chemistry 2027

Reading settings

On this page

A good apparatus diagram communicates the method at a glance. Use clear single lines, label the important apparatus and place each part where it can perform its intended job.

What the skill involves

An apparatus diagram is a simple line drawing that shows the experimental setup and the labels for key equipment.

What you need to know

  • Use clear single lines (no sketchy shading).
  • Label with straight lines that touch the apparatus (no crossing labels).
  • Show the important parts only (not artistic details).
  • For setups with water flow: water in at the bottom, water out at the top.
  • If a measurement is taken, show where it is read (e.g., meniscus, thermometer bulb position).

Putting the skill into practice

Quick Recall (diagram mindset)
  • Show how each piece of apparatus performs its job.
  • In a water-cooled condenser, water enters at the lower connector and leaves at the upper connector.
  • In distillation, the thermometer bulb measures the outgoing vapour at the side arm, rather than the liquid in the flask.

What a clear scientific diagram shows

RuleWhat to doWhat to avoid
Linessingle, continuous, neat linesthick shading / messy sketching
Labelsstraight label lines, clear namesarrows everywhere / label lines crossing
Relevanceinclude essential apparatusdrawing extra clutter
Positionsshow correct placement (bulb, delivery tube)incorrect placement that changes the experiment
Exam Trap: Condenser water direction

Water must enter at the bottom of the condenser and leave at the top so the jacket stays full of water.

Common setups (what must be shown)

Setup“Must show” labels1 key placement detail
Titrationburette, clamp stand, conical flask, white tileread burette at eye level (meniscus)
Gas syringegas syringe, bung, delivery tube, flaskairtight connections (no leaks)
Filtrationfilter funnel, filter paper, beaker/conical flaskfilter paper sits inside funnel
Simple distillationdistillation flask, thermometer, condenser, receiverthermometer bulb at side arm level
Labelled titration setupA vertical burette is held by a clamp stand above a conical flask on a white tile. The burette funnel is removed, the meniscus is read at eye level, and a separate volumetric pipette with a pipette filler is shown.clamp standburettetapfilling funnel removedread meniscus at eye levelconical flaskwhite tilefillervolumetric pipetteNever pipette by mouth.

Main titration setup

Transfer the measured volume safely

Titration setup: clamp the burette vertically, remove the filling funnel, read the meniscus at eye level and deliver into a conical flask on a white tile.
Simple distillation apparatusA heated round-bottom flask connects to a still head. The thermometer bulb is level with the condenser entrance. Vapour passes into a downward-sloping water condenser, with cooling water entering at the lower port and leaving at the upper port, before the distillate collects in an open receiver.electric heater / hot-water bathmixturethermometerbulb level with side armwater condenserwater outwater indistillatereceiver open to air
Simple distillation: the thermometer bulb sits beside the condenser entrance, and cooling water enters the condenser at the lower port.
Fractional distillation apparatusA heated round-bottom flask connects through a fractionating column to a still head. The thermometer bulb is level with the condenser entrance. Vapour passes into a downward-sloping water condenser, with cooling water entering at the lower port and leaving at the upper port, before the distillate collects in an open receiver.electric heater / hot-water bathmixturefractionating columnthermometerbulb level with side armwater condenserwater outwater indistillatereceiver open to air
Fractional distillation: a fractionating column provides repeated condensation and vaporisation before vapour reaches the condenser.

Avoiding common mistakes

  • Drawing “art” (shading, 3D) instead of a clean line diagram.
  • Missing labels for key items (e.g., burette vs “tube”).
  • Putting the thermometer bulb in the liquid during distillation (wrong position).
  • Reversing condenser water direction (water in at top).
  • In titration setups, leaving the funnel in the burette (not part of the titration).

Explaining your method

30-second diagram checklist
  1. Do you have the correct apparatus names?
  2. Are label lines straight and not crossing?
  3. Are the key positions correct (bulb, tubes, water in/out)?
  4. Did you show the measurement point (meniscus/scale)?

Worked examples

Modelled example 1

Distillation Thermometer Position

Core

Problem

In a simple-distillation diagram, where should the thermometer bulb be placed, and what temperature should it measure?
Study the worked solution

  1. Identify the measured substance

    Method

    Choose the vapour leaving the distillation flask.

    Reason

    The relevant boiling temperature is that of the vapour passing into the condenser, not the bulk liquid mixture.

    Working

    Measurement target: outgoing vapour.

  2. Position the bulb

    Method

    Place the thermometer bulb level with the side arm.

    Reason

    Vapour flows past the bulb at that point immediately before entering the condenser.

    Working

    Bulb at side-arm level, not submerged in the liquid.

Common misconception 2

Condenser Water Flow

Find and correct the mistake

Learner diagram

A learner labels “water in” at the top of a condenser and “water out” at the bottom. Correct the labels and explain why the direction matters.

Choose the inlet and outlet positions

Water inlet
Water outlet

View solution step by step

  1. Correct the flow direction

    Method

    Label water in at the bottom and water out at the top.

    Reason

    Incoming water rises through the condenser jacket.

    Working

    Bottom inlet → top outlet.

  2. Explain the purpose

    Method

    Keep the cooling jacket completely filled.

    Reason

    Upward filling displaces air and maintains effective contact between cooling water and the inner tube.

    Working

    Full jacket → efficient cooling and condensation.

Examiner practice 3

Titration Setup Labels

4 marks

Examination question

Name four pieces of apparatus shown in the main titration setup above, excluding the separate pipette panel. [4 marks]

Give four precise apparatus labels

View solution step by step

  1. Delivery apparatus

    1 mark

    Method

    Label the burette.

    Reason

    It measures and delivers the variable titre accurately.

    Working

    Burette.

  2. Support apparatus

    1 mark

    Method

    Label the clamp stand.

    Reason

    It holds the burette vertically and securely.

    Working

    Clamp stand.

  3. Reaction vessel

    1 mark

    Method

    Label the conical flask.

    Reason

    Its shape permits swirling without substantial splashing.

    Working

    Conical flask.

  4. See the end-point clearly

    1 mark

    Method

    Label the white tile.

    Reason

    Its pale background makes the indicator colour change easier to see.

    Working

    Burette, clamp stand, conical flask and white tile. The indicator is a substance in the flask, rather than a piece of apparatus.

Challenge 4

Gas Syringe “0 cm³” Problem

Minimal support

Fault-diagnosis transfer

A reaction visibly produces gas, but the connected gas syringe remains at 0 cm³. Identify a likely setup fault and explain the zero reading.

Infer the hidden fault from the observation

Likely fault
Effect on gas

Hints

Hint 1: path
Trace the gas path from the flask through the bung and delivery tube to the syringe.
Hint 2: pressure
The plunger moves only if produced gas reaches the syringe and raises pressure behind it.
View solution step by step

  1. Locate the likely fault

    Method

    Identify a leak at the bung, tubing or another connection.

    Reason

    Visible gas production makes a leak one plausible cause. A blocked tube or a stuck plunger could also prevent a reading; check the setup before concluding which fault is present.

    Working

    Setup is not airtight.

  2. Explain the reading

    Method

    State that gas escapes instead of pushing the syringe plunger.

    Reason

    Without collected gas entering the barrel, its measured volume does not increase.

    Working

    Likely error: a leak; gas escapes through gaps, leaving the syringe at 0 cm³.

Try it independently

Mind stretcher 1: Spot the Diagram Error (Titration)Extension

Question: A student draws a titration diagram with a funnel left in the burette during the titration. Why is this a problem?

Show Answer

Answer: Liquid can drip from the funnel into the burette during the titration, changing the volume delivered. This makes the titration inaccurate.

Mind stretcher 2: Spot the Diagram Error (Filtration)Extension

Question: A student draws filtration but forgets to include filter paper. What would happen?

Show Answer

Answer: The solid would pass through the funnel into the flask/beaker, so the mixture would not separate. You must show filter paper inside the funnel.

Practise and check

Topic check

See what you know across this topic, then go back to anything you got wrong.

Take the topic check

Syllabus and review details

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