1.5 Section Review: #’s 1-41. Instruments are flawed and measuring always involves estimation.

2. Repeat the measurement several times; Compare the measurement to a standard or accepted value.

3. Last digit displayed is estimated. Estimate.

4. Golf, clay pigeon shooting, temperature readings…are all examples

Chemistry 1.5

Uncertainty in Measurements

I. Making Measurements

A. Digital Scale

1. Last number is estimated.

2. If flickers…use what is “preferred”

3. Use correct units!

B. Scale

1. Ex: graduated cylinder, ruler, etc.

2. Parallax – angle of observation

Which of the following eyes is correct for measuring a graduated cylinder?

a. What is the volume of

the water?

b. Make measurements

as accurate as possible!

43.0 ml

Trash Ball Thrower…

II. Reliability in Measurement

A. Precision – how close a series of measurements are together.

1. Ex: Throwing Darts

B. Accuracy – how close a measurement comes to the “accepted value”.

1. Ex: Throwing Darts

accepted value = bull's-eye

C. Pg. 24 Explanation

Poor AccuracyGood Precision

Good AccuracyGood Precision

Poor AccuracyPoor Precision

1.5 wks (put into notes)

The density of a solid is known to be 8.9 g/cm3. Create a scenario that describes the following situations:

1. High accuracy and high precision

2. Low accuracy and high precision

3. High accuracy and low precision

4. Low accuracy and low precision