151F09 Disc02 sig fig D2L

151F09 Disc02 sig fig D2L - GenChem 2 meeting nd Welcome to...

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GenChem 1 Welcome to your Welcome to your Chem 151 Chem 151 Discussion. Discussion. Where chemistry comes to you! Where chemistry comes to you! 2 nd meeting
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GenChem 2 nd Class Measurement Today’s Agenda: Explore the limits of measuring tools. Connect measurement and significant figures. Form a team Recognize measured numbers do divisions and multiplications to the correct sig figs do addition and subtraction to the correct sig figs. practice, practice, practice
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GenChem So….Join Your Team Try to have at least one laptop per group…
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GenChem Work the problems and take good notes in your lab Note book from discussion is graded for participation. 3 points add up
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GenChem Suppose you need to measure Length and MASS What are the properties of the right right tool? The tool needs to measure the property you are measuring (length, volume, spectra, etc.) The tool needs to measure in the range you need ( accuracy ). The tool needs to meet the precision you need ( tenths, hundreths, etc.) The measurements need to be repeated .
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GenChem You can pick from many tools Usually the more precise The more EXPENSIVE
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GenChem Measure mass to one gram Measure mass to one milligram 0.001 gram Measure mass to one microgram 0.000001 gram Home Postal scale Cost $3.00 Mettler Analytical Balance cost $750-$1000 Sartorius Microbalance Cost $20,000
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GenChem | ׀׀׀׀ | ׀׀׀׀ | ׀׀׀׀ | ׀׀׀׀ | ׀׀׀׀ | ׀׀׀׀ | ׀׀׀ | ׀׀׀׀ | ׀׀׀׀ | ׀׀׀׀ | ׀׀׀׀ | ׀׀׀׀ | ׀׀׀׀ | ׀׀׀׀ | ……. .. 0 1 2 3 4 5 6 |-------|--------|-------|-------|-------|----------|----------|--------- 0 1 2 3 4 5 6 A B Length of the nail using cm cm Measuring Length: Everyone Measure the nail ! cm = centimeter; m-meter Ruler A = cm Ruler B = cm Write your answers down. Then compare and discuss. Let′s think!
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GenChem Did everyone get the same numbers? Is there a possible range of valid results ? About what range? How many numbers should you write down? Which ruler was “best.”? As a group create a rule for properly reading any marked device. | ׀׀׀׀ | ׀׀׀׀ | ׀׀׀׀ | ׀׀׀׀ | ׀׀׀׀ | ׀׀׀׀ | ׀׀׀ | ׀׀׀׀ | ׀׀׀׀ | ׀׀׀׀ | ׀׀׀׀ | ׀׀׀׀ | ׀׀׀׀ | ׀׀׀׀ | ……. .. 0 1 2 3 4 5 6 |-------|--------|-------|-------|-------|----------|----------|--------- 0 1 2 3 4 5 6 A B cm cm The Rule: Find the smallest division -- estimate into that division. Record all the measured numbers and one estimated digit. Let′s think!
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GenChem Two Groups – select A representative To report
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GenChem Rules to read an instrument Group A Group B Save these and erase the board (screen) so we can continue Did everyone get the same numbers? Is there a possible range of valid
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This note was uploaded on 02/06/2012 for the course CHEM 151 taught by Professor Staff during the Fall '08 term at University of Arizona- Tucson.

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151F09 Disc02 sig fig D2L - GenChem 2 meeting nd Welcome to...

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