MYP 6 Science - Chemistry

MYP 6.2.3: The States of matter

Objectives:

  • To understand that state is temperature dependent
  • To understand how to use a Bunsen burner
  • To use a thermometer for recording temperature
  • To present data in the form of a graph
  • To understand the terms melting (fusing), solidifying, boiling, condensing, evaporation.
  • To introduce the law of conservation of energy

The students are introduced to the Bunsen burner for the first time. The parts of the Bunsen should be described as:

  • The base
  • The barrel or chimney
  • The jet
  • The gas tubing

The method of igniting the gas should be demonstrated. All safety points must be noted.

  1. Check that the air supply is closed.
  2. Open the gas supply and ignite the gas using a lighted splint

They should be given an opportunity to try heating a glass test tube containing water with the yellow flame and the blue flame. From this they can see that only the blue flame can be used for heating. The flame should be semi-yellow when not in use (safety flame). Explain that the yellow flame pollutes the air in the laboratory with carbon (soot) and carbon monoxide (a poisonous gas)

Student Activity

A cooling curve experiment

The students can prepare a cooling curve by heating up a sample of naphthalene (perhaps phenol - corrosive) in a test tube using a water bath to a temperature of 80ºC.

They can then allow it to cool (cool water bath) stirring throughout and recording the temperature every 30 seconds.

They then plot a graph of the temperature (y-axis) against time (x-axis).

Follow up discussion on the shape of the curve. Explain that heat energy is released as the particles bond together in the state change from liquid to solid.

What energy change would you expect from the reverse process (melting).

Discussion of other changes of state and the energy changes involved.


Resource

Science Explorer - Chemical Building Blocks Section 2 - Changes of States pp 42-53

Spotlight Science 7: p 6-7, 90-91, 96-101,

Video

Bunsen burner


 
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