Scientific Measurement

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Slide 1

Measuring

Volume

Temperature

Mass

Slide 2

Reading the Meniscus

Always read volume from the bottom of the meniscus. The meniscus is the curved surface of a liquid in a narrow cylindrical container.

Slide 3

Try to avoid parallax errors.

Parallax errors arise when a meniscus or needle is viewed from an angle rather than from straight-on at eye level.

Correct: Viewing the meniscus at eye level

Incorrect: viewing the meniscus from an angle

Slide 4

Graduated Cylinders

The glass cylinder has etched marks to indicate volumes, a pouring lip, and quite often, a plastic bumper to prevent breakage.

Slide 5

Measuring Volume

Determine the volume contained in a graduated cylinder by reading the bottom of the meniscus at eye level.

Read the volume using all certain digits and one uncertain digit.

Certain digits are determined from the calibration marks on the cylinder.

The uncertain digit (the last digit of the reading) is estimated.

Slide 6

Use the graduations to find all certain digits

There are two unlabeled graduations below the meniscus, and each graduation represents 1 mL, so the certain digits of the reading are…

52 mL.

Slide 7

Estimate the uncertain digit and take a reading

The meniscus is about eight tenths of the way to the next graduation, so the final digit in the reading is .

The volume in the graduated cylinder is

0.8 mL

52.8 mL.

Slide 8

10 mL Graduate

What is the volume of liquid in the graduate?

_ . _ _ mL

6

2

6

Slide 9

25mL graduated cylinder

What is the volume of liquid in the graduate?

_ _ . _ mL

1

1

5

Slide 10

100mL graduated cylinder

What is the volume of liquid in the graduate?

_ _ . _ mL

5

2

7

Slide 11

Self Test

Examine the meniscus below and determine the volume of liquid contained in the graduated cylinder.