L3 - Melting & Boiling Points

objectives

• Recalled (Yr7) change of state

activity 2 - graphing our results

1.ALWAYS USE A PENCIL

2.The thing that has changed (independent variable) should go along the bottom of the graph

3.The thing that has been measured (dependent variable) should go up the side of the graph

4.Choose your scales so that the graph fills all of the page

5.Start both your scales at 0 and make sure they go up in regular intervals e.g. 2 4 6 8 (not 3 4 7 23 etc)

6.Make sure you label your axis and ALWAYS INCLUDE THE UNITS e.g. seconds, meters, etc

7.USE A SCATTER GRAPH (it is very unusual to use a bar graph in science)

8.Use a LINE (or curve) of best fit. Don’t join up the crosses

9.Give your graph a title that tells the reader exactly what it shows

Why do different substances boil at different temperatures?

• Different types of particles have different forces of attraction holding them together.
• Some forces are strong so it’s difficult to break the particles apart.
• Some forces are weak, so it’s easy to break those types of particles apart.
• What does this mean for the temperature when substances will melt?

Forces of Attraction

Is there a difference between boiling and evaporating???