Water cycles and Changes in State
Factors Affecting Rate of Evaporation
This science revision note aims to help your child understand how to explain evaporation concepts clearly.
But before you read on, you might want to download this entire revision notes in PDF format to print it out for your child, or to read it later.
This will be delivered to your email inbox.
Rachel conducted an experiment. She had three different containers with an equal volume of water in each, as shown in the diagram below. She left the containers open for 20 minutes under the hot sun.
After 20 minutes, which of the containers (A, B or C) would contain the least volume of water? Explain your answer.
STEP 1
Identify the factor affecting the rate of evaporation that is being changed here.
In the lesson notes, your child has learnt 3 factors affecting rate of evaporation.
- Presence of Wind
- Exposed surface area
- Temperature of the liquid
We use the acronym WET.
Now, we have to identify which is the relevant factor for the above question.
- The temperature of water: As all containers were placed in the same place, this factor is not changed.
- Presence of wind: As all containers were placed in the same place, this factor is not changed.
- Exposed surface area of water: The shapes of the containers are different and their openings are of different sizes, as seen by the diagram. Hence, the exposed surface area of water is the factor being changed.
STEP 2
Explain how the factor changed affects the rate of evaporation.
How does exposed surface area affect rate of evaporation? The greater the exposed surface area of water, the faster the rate of evaporation, the lower the volume of water left at the end of the experiment.
Step 3
Identify which container will contain the least volume of water after 20 minutes.
Let’s work backwards: Least water left the fastest rate of evaporation the greatest exposed surface area
Which container has the greatest exposed surface area?
Container B
Hence, Container B will contain the least volume of water after 20 minutes.
FINALLY, put your answers together.
Question: After 20 minutes, which of the containers (A, B or C) would contain the least volume of water? Explain your answer.
Answer: Container B will contain the least volume of water after 20 minutes. Container B has the greatest exposed surface area, so the water in Container B has the fastest rate of evaporation. Hence, Container B will have the least volume of water left after 20 minutes.
Note: Your answer must state the factor affecting the rate of evaporation. For this question, the relevant factor is exposed surface area.
Common mistakes
Wrong answer: Container B will contain the least volume of water after 20 minutes. Container B has a greater exposed surface area, so the water in Container B has a faster rate of evaporation. Hence, Container B will have less water left after 20 minutes.
Since you are comparing more than two containers, you have to use superlatives (eg. greatest, fastest) to explain your answer!
You can download this revision notes so your child can revise them anytime.
This will be delivered to your email inbox.
Your child can read any one of our free revision notes here.
>>> https://scienceshifu.com/science-revision-notes/
These notes provide a quick revision for your child before he/she sits for the exams.
Join the ScienceShifu Channel to get the latest learning tips.
Benefits of joining ScienceShifu on Telegram:
– Be the first to receive science revision notes from us
– Receive special promotions on all our online courses.
Click on the button below to join the ScienceShifu channel:
Follow the ScienceShifu Instagram Channel to learn more science concepts
Benefits of joining Instagram:
– Watch out for interesting posts from ScienceShifu explaining science concepts
– Short videos where I will be going through past year exam questions
Click on the button below to follow the ScienceShifu Instagram Channel:
Talk again soon!
Andy Ling
Guiding your child to be the master of science concepts
We strive to improve the revision notes for your child.
Let us know what you would like your child to learn by leaving your comments below.
