3.14 To measure the volume of liquid substances

Natural sciences

Matter, measuring and reactions

Educator section

Memorandum

1. Answers may vary from one individual to another:

• Meniscus: This is the curvature of the surface of a liquid due to the liquid's clinging to the sides of the container, to form an upside-down bow.

Assignment 7:

You sip up the liquid and put your finger on the top end as quickly as possible. Then you lift your finger and let the water drain until the meniscus is level with the line. You use it when you want to measure exactly 25 mℓ or 50 mℓ (or any size of the pipette) to add to something.

• Burette: The readings will depend on the size of the spoons.

Leaner section

Content

Activity: to measure the volume of liquid substances [lo 1.1, lo 2.3]

MEASURING WITH THE HELP OF A MEASURING CYLINDER

Volume refers to the contents of particular spaces. When you buy a cold drink, you pay for a particular amount of liquid that fills a specific space.

This amount of cold drink can also be described as the volume of cold drink.

Volumes can be measured with the help of a measuring cylinder, a burette or a pipette.

By using a measuring cylinder frequently, you will develop your skill in estimating correctly.

1. Use a typical measuring cylinder to measure the volume of the following containers (and to see how accurate your estimation is):

Two basic rules have to be considered for taking a correct reading from a measuring cylinder:

• Your eye should be in line with the lower level of the surface of the water (meniscus);
• The measuring cylinder has to be placed on a level surface and not be tilted, as in the illustrated example!

Explain what a meniscus is, using your own words:

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MEASURING WITH THE HELP OF A PIPETTE

Study the following illustration to get to know a pipette:

ASSIGNMENT 7

• Give your own explanation of how a pipette is used to obtain a reading:

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MEASURING WITH THE HELP OF A BURETTE:

A burette is used to measure liquid volume.

It is particularly suitable for measuring volumes smaller than 50 cm.

Burettes are calibrated (marked in divisions) from top to bottom and usually are more accurate than measuring cylinders.

The amount of liquid that is tapped from a burette can simply be read from the burette by checking the level of the meniscus.

Now use the burette to measure the following volumes:

Assessment

Learning Outcome 1: The learner will be able to act confidently on curiosity about natural phenomena, and to investigate relationships and solve problems in scientific, technological and environmental contexts.

Assessment Standard 1.1: We know this when the learner plans investigations: plans simple tests and comparisons and considers how to conduct these properly.

Learning Outcome 2: The learner will know and be able to interpret and apply scientific, technological and environmental knowledge.

Assessment Standard 2.3: We know this when the learner interprets information by identifying key ideas in text, finding patterns in recorded data, and making inferences from information in various forms (e.g. pictures, diagrams, text).