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Warmup (5 min)

Warmup (5 min). Have your packet out!. 1. 10 3 / 10 -4 = 2. (10 19 ) (10 2 ) = 3. Round 5.678 to 3 digits 4. 16 = 3.0 5. (56.8)(6.0) =. All answers will be discussed during lecture, but see if you can do these NOW!. *You will need a calculator today.

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Warmup (5 min)

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  1. Warmup (5 min) Have your packet out! 1. 103 / 10-4 = 2. (1019) (102) = 3. Round 5.678 to 3 digits 4. 16 = 3.0 5. (56.8)(6.0) = All answers will be discussed during lecture, but see if you can do these NOW! *You will need a calculator today.

  2. Introduction to Quantitative ChemistrySignificant FiguresRoundingScientific Notation Take notes on Introduction to Quantitative Chemistry Notes/Problems and ALSO on a separate sheet of paper

  3. Quantitative ObservationsQualitative Observations Involves measured Involves general values and numbers observations without examples? measurement Ex. It is 36.7⁰C outside today The river is 31.5 m deep The cheese costs $4.25 per pound Ex. It is hot today The building is tall I do not weigh a lot

  4. What are significant figures? (‘sig figs’) “Important numbers”?!?!?! 11.818 sec vs 12.000 sec? Who cares? In swimming/track, the stopwatch is VERY precise • There is a reason for placing zeros in a measured value when they are not important for calculation purposes. Significant does not mean IMPORTANT. • The number of sig figs reported in a value implied the degree of precision of the instrument used to make the measurement.

  5. Which digits are significant? 0.00450600

  6. With a partner, take 2 minutes to discuss how many significant figures are in each of these values: 3 2 1) 1908 2) 0.0025 3) 15.9 5 5 1 4) 0.7040 5) 340.06 6) 140. vs 140.0 vs 140

  7. Pacific Atlanticdecimal present decimal absent 0.00805 100800 4.000100 2000 3 4 7 1 Pick your ocean Skip zeros, find first 1-9 digit Count all digits, even the zeros

  8. Round these values to four significant figures: • 0.0587920 b. 1670.48564 c. 3450824 a. 0.05879 b. 1670. c. 3451000 Rules for Rounding: • If the digit to be removed is < 5, the preceding digit remains unchanged Ex. 25.44 rounds to 25.4 • If the digit to be removed is ≥ 5, then the preceding digit is increased by 1 Ex. 25.46 rounds to 25.5

  9. 16 = b. (56.8)(6.0) = 3.0 c. 590.0 = d. (324.6)(815.991) = 611 Perform each operation and round answers to the appropriate number of sig figs 340 5.3 0.966 264900 Rules1) To see how many sig figs to use in your answer, look at the # sig figs in the values given to you in the problem.2) If the starting values have different numbers of sig figs, use the lower # of sig figs

  10. 7.442 - 7.429 0.013 c. 16.82 + 3.2257 20.0457 20.05 Perform the indicated calculations on the following measured values, giving the final answer with the correct number of significant figures. • 2.86 + 3.4921 + 1.3 7.6521 7.7 Round to the last digit that they have in common. I will sometimes break this rule for one reason or another…… just go with it.

  11. Scientific notation is used to simplify very small or large numbers. It expresses a number as: • a number between 1 and 10 and 2) a power of 10 Ex. 6780  6.780 x 103 PART 1: Identifying correct scientific notation Which of these numbers are/are not written in correct scientific notation? 3.57 x 10-8 4.23 x 10-2 75.3 x 10-10 2.92 x 109 0.00345 x 104 Gross!

  12. Move the decimal to the right, exponent = negative 0.00032  3.2 x 10-4 PART 2: Changing a value into scientific notation Move the decimal to the left, exponent = positive. 32000  3.2 x 104 a. Change 0.00045 to scientific notation b. Express 1.28 x 10-5 in standard (regular) notation a. 4.5 x 10-4 b. 0.0000128 Put the following values into scientific notation using 3 significant figures: 1) 0.00980 3) 25900.0 2) 10.5 4) 0.043 2.59 x 104 9.80 x 10-3 1.05 x 101 4.30 x 10-2

  13. 5 x 10-3 4 0.0015 1 x 106 5.05 x 103 0.00000335 220000 2.5 x 10-4 Take 3 minutes to fill in the missing pieces from this chart

  14. PART 3 Multiplying, dividing numbers in scientific notation Ex A: (2.5 x 105)(2.0 x10-2) = 5.0 x 103 Ex B: 6.8 x 107 1.7 x 103  ****make sure to group values in your calculator using parenthesis!!!!!!!!!!!!!! = 4.0 x 104 (add a zero bc you need 2 sig figs) ( )

  15. 1.78 x 10-11 7.37 x 103 Do the last 5 on your own. I will give answers in 3 minutes. 1. (8.31 x 10-1)(2.14 x10-11) = 2. (3.51 x 10-3)(2.10 x106) = 3. 9.1 x 104 =4. (5.9 x 104) = 11 x 108 (7.2 x 10-3) 5. (5.5 x 104) (1.1 x106) = (3.2 x 108) 8.2 x 106 8.3 x 10-5 1.9 x 102

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