Chapter One Chemistry and Measurement

Copyright © Houghton Mifflin Company. All rights reserved.1 | 2 Question Which of the following is an example of a theory? a) Solution A is a darker red color than solution B. b) All matter is composed of tiny, indivisible particles called atoms. c) The grass is green. d) The temperature of the water is 45°C.

Copyright © Houghton Mifflin Company. All rights reserved.1 | 3 Answer b) All matter is composed of tiny, indivisible particles called atoms. A theory is a tested explanation of basic natural phenomena. The other potential answers are observations.

Copyright © Houghton Mifflin Company. All rights reserved.1 | 4 Question The boiling point of a liquid was measured in the lab, and the following results were obtained: TrialBoiling Point 122.0°C ± °C ± °C ± 0.1 The actual boiling point of the liquid is 28.7°C. The results of the determination of the boiling point are a) accurate and precise. b) precise but inaccurate. c) accurate but imprecise. d) inaccurate and imprecise.

Copyright © Houghton Mifflin Company. All rights reserved.1 | 5 Answer b) precise but inaccurate. The measurements are precise because they are all in close agreement with one another. However, they are relatively far from the true value, so they are inaccurate.

Copyright © Houghton Mifflin Company. All rights reserved.1 | 6 Question _______ is the agreement of a particular value with the true value. a) Certainty b) Precision c) Accuracy d) Systematic error e) Random error

Copyright © Houghton Mifflin Company. All rights reserved.1 | 7 Answer c) Accuracy If a measurement is in close agreement with the true value, it is an accurate measurement.

Copyright © Houghton Mifflin Company. All rights reserved.1 | 8 Question The glassware shown to the right is called a buret. The buret is filled to the zero mark (at the top) with a solution and the solution is transferred to a beaker. What volume of transferred solution should be reported? a) 20 mL b) 22 mL c) 22.0 mL d) mL e) 28 mL

Copyright © Houghton Mifflin Company. All rights reserved.1 | 9 Answer c) 22.0 mL In a measurement we always include one uncertain digit. The graduations on this buret are 1-mL graduations, so we can estimate the tenths place.

Copyright © Houghton Mifflin Company. All rights reserved.1 | 10 Question After calculating an answer in the lab, the number on your calculator reads “ ” If the number is to have five significant figures, what result should you report? a) b) c) d) e)

Copyright © Houghton Mifflin Company. All rights reserved.1 | 11 Answer c) The leading zeros (to the left of the 2) are not significant, but the captive zero (between the 3 and the 6) and terminal zero (to the right of the 6) are significant.

Copyright © Houghton Mifflin Company. All rights reserved.1 | 12 Question How many significant figures are in the number ? a) One b) Two c) Three d) Four e) Five

Copyright © Houghton Mifflin Company. All rights reserved.1 | 13 Answer d) Four The leading zeros (to the left of the 3) are not significant, but the captive zero (between the 3 and the 4) and terminal zero (to the right of the 4) are significant.

Copyright © Houghton Mifflin Company. All rights reserved.1 | 14 Question Express 3140 in scientific notation. a) 3.14 × 10 3 b) 3.14 × 10 −3 c) × 10 3 d) × 10 −3

Copyright © Houghton Mifflin Company. All rights reserved.1 | 15 Answer a) 3.14 × = 1000, and 3.14 × 1000 = We lose the zero because it is not significant (it is a placeholder). If the zero were significant we should write the number as “3140.”.

Copyright © Houghton Mifflin Company. All rights reserved.1 | 16 Question Which of the following describes an exact number? a) A basketball has a diameter of 9.39 inches. b) There are 60 seconds in a minute. c) π = d) A student walked 10 minutes to get to class.

Copyright © Houghton Mifflin Company. All rights reserved.1 | 17 Answer b) There are 60 seconds in a minute. Quantities that are derived from the definition of a unit are exact numbers.

Copyright © Houghton Mifflin Company. All rights reserved.1 | 18 Question The beakers below have different precisions as shown. You pour the water from these three beakers into one container. What should be the volume in the container reported to the correct number of significant figures? a) mL b) mL c) 78.8 mL d) 79 mL

Copyright © Houghton Mifflin Company. All rights reserved.1 | 19 Answer d) 79 mL In a measurement we always include one uncertain digit. So, the first measurement can be 26.4 mL ± 0.1 mL, the second can be 26 mL ± 1 mL, and the third can be mL ± 0.01 mL. When adding, the result has the same number of decimal places as the least precise measurement, in this case, to the ones place. So the answer is = mL, which must be rounded to 79 mL.

Copyright © Houghton Mifflin Company. All rights reserved.1 | 20 Question Which of the following is not an example of a derived quantity? a) Pressure b) Area c) Density d) Volume e) Length

Copyright © Houghton Mifflin Company. All rights reserved.1 | 21 Answer e) Length Derived quantities are combinations of base units. Pressure is force per unit area (such as kg/(m. s 2 )), area is volume squared (such as m 2 ), density is mass per unit volume (kg/m 3 ), and volume is length cubed (such as m 3 ).

Copyright © Houghton Mifflin Company. All rights reserved.1 | 22 Question Convert kg to milligrams. a) mg b) 5853 mg c) × 10 6 mg d) × 10 −6 mg

Copyright © Houghton Mifflin Company. All rights reserved.1 | 23 Answer c) × 10 6 mg The number of milligrams is larger than the number of kilograms because a kilogram is larger than a milligram. There are 1000 g/kg and 1000 mg/g, so the number of milligrams per kilogram is 10 3 g/kg x 10 3 mg/g = 10 6 mg/kg.

Copyright © Houghton Mifflin Company. All rights reserved.1 | 24 Question Ethylene glycol has a density of g/mL. What volume must be poured into a graduated cylinder to give 21.1 g of ethylene glycol? a) mL b) 18.9 mL c) mL d) 23.5 mL e) mL

Copyright © Houghton Mifflin Company. All rights reserved.1 | 25 Answer b) 18.9 mL Since d = m/V, the formula can be rearranged to give V = m/d. Substituting in the values gives The number of significant figure in the answer is three because the mass has only three significant figures.