Chapter1_soln_even

Chapter1_soln_even - Chapter 1 Chemical Foundations 16 a...

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Chapter 1 Chemical Foundations 16. a. Law versus theory: A law is a concise statement or equation that summarizes observed behavior. A theory is a set of hypothesis that gives an overall explanation of some phenomenon. A law summarizes what happens; a theory (or model) attempts to explain why it happens. b. Theory versus experiment: A theory is an explanation of why things behave the way they do, while an experiment is the process of observing that behavior. Theories attempt to explain the results of experiments and are, in turn, tested by further experiments. c. Qualitative versus quantitative: A qualitative observation only describes a quality while a quantitative observation attaches a number to the observation. Examples: Qualitative observations: The water was hot to the touch. Mercury was found in the drinking water. Quantitative observations: The temperature of the water was 62 ºC. The concentration of mercury in the drinking water was 1.5 ppm. d. Hypothesis versus theory: Both are explanations of experimental observation. A theory is a set of hypothesis that has not been tested over time and found to still be valid, with (perhaps) some modifications. 18. a. No b. Yes c. Yes 20. Accuracy: How close a measurement or series of measurements are to an accepted or true value. Precision: How close a series of measurements of the same thing are to each other. The results, average = 14.91 ± 0.03% are precise (close to each other) but are not accurate (not close to the true value). 22. Many techniques of chemical analysis need to be performed on relatively new materials. Thus, a separation step often is necessary to remove materials that will interfere with the analytical measurement. 24. a. exact b. inexact; 0.9144m/yd is exact (see Exercise 1.23c). Thus, there are 1/0.9144 = 1.093613 … yd/m c. exact d. inexact ( has an infinite number of decimal places.) 26. a. 1 00 (1 S.F.) b. 1.0 × 10 2 (2 S.F.) c. 1.00 × 10 3 (3 S.F.) d. 100 . (3 S.F.) e. 0.0048 (2 S.F.) f. 0.00480 (3 S.F.)
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g. 4.80 × 10 -3 (3 S.F.) h. 4.800 × 10 -3 (4 S.F.) 28. a. 5 × 10 2 b. 4.8 × 10 2 c. 4.80 × 10 2 d. 4.800 × 10 2 30. For multiplication and/or division, the result has the same number of significant figures as the number in the calculation with the fewest significant figures. a. 01 . 1 273 0821 . 0 102 . 0 × × = 2.26 35 = 2.26 b. 0.14 × 6.022 × 10 23 = 8.4 31 × 10 22 = 8.4 × 10 22 Since 0.14 only has two significant figures, the result should only have two significant figures. c.
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Chapter1_soln_even - Chapter 1 Chemical Foundations 16 a...

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