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Chemistry II - Measurement

Page history last edited by David Young 7 years, 1 month ago

 


 

General Discussion

There is a general discussion forum for Mr. Young's students.  You can use this forum to post questions for your fellow classmates and also look at historical discussion of similar topics.  

Chemistry I Forum

Chemistry II HAIKU Page Discussion Forum 

 

 

 

Instructional Materials

The learning resources for this unit are organized in one place on this page.  Here you can find guidelines to make up missed work (or to work ahead), a description of upcoming assessments, powerpoints used in class, etc.

 

Quick Links

Unit 1 Resource Folder - Rubrics and Answers to Assignments

Mr. Young's Scientific Skill Toolbox

Chemistry II Haiku Page

 

Assessment Summary

Item  How to be prepared and successful 

Quiz 1 - Powers of 10

Complete packet worksheets, check your answers online, discuss issues with classmates

or your teacher.  Review Learning Check 1 and Numeracy Assessment pre-test.

Quiz 2 - Significant Figures and Math Skills

Complete packet worksheets, check your answers online, discuss issues with classmates

or your teacher.  Review Learning Check 2 and Numeracy Assessment pre-test.

 

Lab - Density of Ethanol  
Quiz 3 - Measurement, Accuracy and Precision  

 

 

Learning Tasks

 

Task 1 - Numeracy Pre-test

This is a 40 question multiple choice test designed to survey the class's understanding of numeracy and measurement concepts.  This test DOES NOT count toward your grade but will be used by Mr. Young to inform teaching practice.  A paper copy of the test will be given to you but we will use HAIKU to enter answers.  Follow the link below to access the electronic version of the assessment.

 

 Practice: U1 - Numeracy Assessment (Pre-test)

 

Task 2 - Orders of Magnitude and Powers of 10

 

Task 1 looks at the topics of scientific notation and metric prefixes.  As numbers in science can be both very small and very large, scientists need ways to represent these quantities efficiently.  Scientific notation and the SI system of measurement both utilize powers of 10 to simplify working with large and small quantities.

  • work through the numeracy packet sections covering these topics
  • additional information, video tutorials and examples can be found on the following pages

 

 

Script Practice: U1 - Learning Check 1 - Powers of 10

 

Task 3 - Significant Figures

 

No measurement in science is exact.  When we make measurements, the last recorded digit is an estimate.  

Since measurements are at best, very good estimates, we are limited when measurements are used in calculations.  Final answers are rounded to show how estimates in measurement limit our confidence in the calculated value.  This concept is described as significant figures (or digits).

 

The figure below shows how the measuring instrument you choose can affect the detail of a measurement and in turn the number of significant figures.  

 


  • work through the numeracy packet section on significant figures
  • additional information, video tutorials and examples can be found on the following page

 

Script Practice: U1 - Learning Check 2 - Significant Figures

 

Task 4 - Math Skills

Math skills - rearranging equations, correct substitution, performing the necessary unit conversions, being able to use your calculator, and checking your results - are crucial to success in any science subject.

 

Task 5 - Measurement, Accuracy and Precision

 

How long is the pencil?

 

What is the temperature reading on the thermometer?

 

 

 

ABSOLUTE UNCERTAINTIES - KEY CONCEPTS

 

Takes into account both limitations of instrument scale, AND how it is being used.

 

An absolute uncertainty value has only ONE significant figure.

 

The place value of the uncertainty matches the place value of the estimated digit in the measurement. 

 

 

 

 

PERCENTAGE or RELATIVE UNCERTAINTIES - KEY CONCEPTS

 

Expressed as a % of the measurement value and can be more than one significant figure.

 



Both of these graduated cylinders are being used to measure the same volume of liquid.

 

Record a measurement for each cylinder with absolute uncertainty.

 

Calculate the % uncertainty for each measurement.

 

Comment on 

 

a) which is the better instrument to use and why

 

b) why percent uncertainty is a useful value 

 

Sometimes it is not so obvious . . . compare these two measurements

 

945 ± 5 m      and        8.7 ± 0.3 cm  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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