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Grade 8 Beginner About 15 min Version 1 Awaiting review Premium

Reading a laboratory thermometer

Temperature tells us how hot or cold something is. It is measured in degrees Celsius (°C) with a thermometer. In a laboratory thermometer, a coloured liquid in a thin glass tube expands as it gets hotter and rises up the scale. Water freezes at 0 °C and boils at 100 °C at sea level. The thermometer takes time to reach the temperature of what it is measuring, so keep the bulb in the liquid and wait until the column stops moving before you read it.

What you will learn

  • Read a laboratory thermometer to the nearest degree.
  • Explain why a thermometer must be left until its reading is steady.
  • Recall the melting and boiling points of water.

Before you start

  • Read a scale that includes negative numbers.

Materials

  • Ice water, tap water, warm water and boiling water

Equipment

  • Laboratory thermometer (−10 °C to 110 °C)
  • Beakers and a stopwatch

Procedure

  1. Choose a sample and wait for the reading to settle.
  2. Use the magnifier to read the top of the red column and move the reading slider to it.
  3. Record the temperature of ice water, tap water and boiling water once each reading is steady.

How this simulation is simplified

  • The thermometer starts at a room temperature of 25 °C and approaches the sample's temperature, getting about two-thirds of the way every 20 s.
  • The water boils at 100 °C (sea level).