notestest1 - Notes for test 1 chapters 2, 3, and 4 Chapter...

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Notes for test 1 chapters 2, 3, and 4 Chapter 2 Aug. 26 Rules: Significant Figures 1. How many significant figures in (a) 455 (b) 1233 (c) .12 Answer: (a) 3 (b) 4 (c) 2 RULE: All non-zero numbers are significant. 2. How many significant figures in (a) 1002 (b) 506 Ans: (a) 4 (b) 3 Remember: Ending zeros(where there is no decimal point) and zeros before the first non-zero number are not significant. 3. How many significant figures (a) 0.012 (b) 0.0140 Ans: (a) 2 (b) 3 RULE: Zeros before the first non-zero number are not significant. Ending zeros where there is a decimal point are significant. 4. How many significant digits (a) 1.23 X 10 3 (b) 1.00 X 10 -3 Ans: (a) 3 (b) 3 RULE: When written in scientific notation, all numbers are significant. 5. How many significant digits (a) 100 (b) 1000 (c) 100.0 Ans: (a) 1 (b) 1 (c) 4 ( if there is a decimal after ending zeros, they are significant.) RULE: Ending zeros, with no decimal point behind them, may or may not be significant. You have to know where the number came from. So, consider them not significant unless a line is drawn above the zeros. Rules for Multiplication and Division: 6. Write the answer to each problem with then correct number of significant figures. (a) 4.45 X 1.3 = 578.5 ( 580) (b) 1233/11 = 112.09 ( 110) RULE: When multiplying or dividing, the answer may have no more significant figures than the least in the numbers being multiplied or divided.
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Rules for Addition and Subtraction 7. Write the answer to each problem with the correct umber of significant figures. (a) 1.23 + 3.1 = 4.33 ( 4.3) (b) 5.44 + 6.112 = 11.552 (11.55) RULE: The answer may have not more digits to the right of the decimal point than the least number to the right of the decimal point in numbers being added or subtracted. ( Note this rule is based on decimal points not significant figures.) Scientific Notation 8. Write in Scientific Notation: (a) 2334 ( 2.334 X 10 3 ) (b) .00120 (1.20 X 10 -3 ) 9. Write in non-scientific: (a) 1.23 X 10 4 (12300) (b) 2.4 X 10 -4 ( .00024) If you were absent, go to the website and open link 8 and do pages 1-3. Do the following before the next class period. 1. Have your scientific calculator 2. Have a set of note cards ( 50 should be enough for all semester.) Aug. 31 Try this practice exam: 1. How many significant figures in each. (a) 122 (b) 0.005860 (c) 3.45 X 10 4 (d) 1000.0 (e) 1000 (f) 12006 Answers: (a) 3 (b) 4 (c) 3 (d) 5 (e) 1 (f) 5
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2. Write the answer with the correct number of significant figures: (a) 141 X 25.01 = 3526.41 (3530) (b) 15.44/ 2.3 = 6.696 (6.7) (c) 6.11 + 5.022 = 11.132 (11.13) (d) 12.345 – 0.5 = 11.845 (11.8) 3. Write in scientific notation: (a) 1455 (1.455 X 10 3 ) (b) 0.00221 (2.21 X 10 -3 ) 4. Write in non-scientific notation: (a) 2.34 X 10 -3 (.00234) (b) 1.24 X 10 4 (12400) Board Problems 1. How many sig digs in each number: (a) 124 (b) 0.0412 (c) 2.010 (d) 62.00 (e) 6200 (f) 6200 – line over last two zeros. Answers (a) 3
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This note was uploaded on 01/03/2011 for the course CHEM 3302 taught by Professor Dickpowell during the Spring '10 term at UT Arlington.

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notestest1 - Notes for test 1 chapters 2, 3, and 4 Chapter...

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