This is a slide deck that can be used by those teaching or studying CSEC Science. (CSEC - Caribbean Secondary Education Certificate). It is designed to function as a self-directed lesson, but it may be used during online video or face-to-face sessions.

1. CSEC (Form 4-5 | Grade 8=9) Science
SECTION: B - The Home and Workplace
Evaporation &
Cooling
KEISHA S LEWIS (C)2020 | biospecialist2019@gmail.com

2. OBJECTIVES SYLLABUS OBJECTIVE
Candidate should be able to:
Explain the cooling effects of evaporation;
LESSON OBJECTIVES
By the end of this lesson, the student should be able to:
Describe the differences between boiling and evaporation
Define the latent heat of vaporisation;
Explain how sweating helps a person to cool down;

3. INTRODUCTION
The video that follows shows the evaporation of water off a surface.
Do you think the temperature of that surface will change?
KEISHA S LEWIS (C)2020 | biospecialist2019@gmail.com

5. INTRODUCTION
If you measured the temperature of the concrete before and after
evaporation, you would have seen that the concrete became cooler.
This is because evaporation has a cooling effect, called the EVAPORATIVE
COOLING EFFECT.
In this lesson, we will explore this effect and how sweating uses it to keep
you cool.
KEISHA S LEWIS (C)2020 | biospecialist2019@gmail.com

6. EXPLANATION Evaporation and boiling are very similar. But there
are some major differences…
Click the blue text below. It is a link to an activity
describing the similarities and differences between
the two. Go through the activity and list the
similarities and differences in your notebook. Share
your answers in your Class Group.
https://h5p.org/node/538681
KEISHASLEWIS(C)2020|biospecialist2019@gmail.com

7. EXPLANATION cont’d/…
Take a look at this graph. It
is called a HEATING
CURVE.
This graph shows the
increase in temperature of
water as more and more
heat is added to it.
Did you notice what
happens at 0℃ and at
100℃?
KEISHASLEWIS(C)2020|biospecialist2019@gmail.com

8. EXPLANATION cont’d/…
At 100℃, the water has reached its BOILING POINT.
At that temperature, the water molecules uses the heat energy to change from
liquid to gaseous state, all at once.
Since the energy is being used, the temperature stays the same for a while.
This energy, used to change from liquid to gas, is called the
LATENT HEAT OF VAPORISATION.
KEISHA S LEWIS (C)2020 | biospecialist2019@gmail.com

9. Heat Energy
is being
used
KEISHASLEWIS(C)2020|biospecialist2019@gmail.com

10. This LATENT HEAT OF VAPORISATION
is also used by Evaporation.
This is why Evaporation cools things
down. It meets its Latent Heat needs
by sucking heat energy from its
surroundings.
With loss of heat, the surroundings
cool down.
KEISHASLEWIS(C)2020|biospecialist2019@gmail.com

11. PLEASE TRY THIS AT HOME
If you have access to the equipment, try this experiment.
Share your results with the class group. Did you get similar results?
https://h5p.org/node/544761
KEISHA S LEWIS (C)2020 | biospecialist2019@gmail.com

12. SUMMARYI
● Boiling and Evaporation are both processes that change a
substance from liquid to gaseous state.
● However, there are many differences between the two
processes. For example, boiling only occurs at a specific
temperature, whereas evaporation can occur at any
temperature.
● Conversion from one state to another either uses energy or
releases energy. Change from liquid to gas uses energy. This
heat energy is called the latent heat of vaporisation.
KEISHA S LEWIS (C)2020 | biospecialist2019@gmail.com

13. SUMMARYII
● Evaporation meets the need for latent heat of vaporisation by
sucking heat energy from its surroundings. The surroundings
therefore become cooler.
● The effect that evaporating liquid has on its surroundings is called
evaporative cooling.
● Sweating uses the evaporative cooling effect. When sweat dries off
your skin, it takes some of the heat with it, thus cooling you down.
KEISHA S LEWIS (C)2020 | biospecialist2019@gmail.com

15. REFERENCES
● Anon, viewed on 21st June 2019,
<https://pxhere.com/en/photo/1367513
>
● Community College Consortium for
Bioscience Credentials, Heating-
curve.png, viewed on 21st June 2019, <
https://commons.wikimedia.org/wiki/File:
Heating-Curve.png >
● Etienne Marais, viewed on 21st June
2019,
<https://www.pexels.com/photo/boil-
boiling-water-bubbles-water-194034/ >

16. REFERENCES
● Eusebius Ngemera, 21 Sept 2011,
Timelapse of Water Evaporating from
Concrete Ground, viewed on 21st June
2019, <https://youtu.be/HuF0Xg4MlJI>
● kmicican, Cycle Phase Change - Free Vector
Graphics, viewed on 21st June 2019,
<https://pixabay.com/vectors/cycle-
phase-change-process-diagram-
2019530/>
● Science Beyond, 9th August 2012, Water
Evaporation Test, viewed on 1st July 2019,
<https://youtu.be/nWWAETXtEbk>