1 / 25

Chapter One

Chapter One. Chemistry and Measurement. 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.

kasimir-swanson
Télécharger la présentation

Chapter One

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter One Chemistry and Measurement

  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.

  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.

  4. Question • The boiling point of a liquid was measured in the lab, and the following results were obtained: • TrialBoiling Point • 1 22.0°C± 0.1 • 2 22.1°C± 0.1 • 3 21.9°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.

  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.

  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

  7. Answer • c) Accuracy • If a measurement is in close agreement with the true value, it is an accurate measurement.

  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) 22.00 mL e) 28 mL

  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.

  10. Question • After calculating an answer in the lab, the number on your calculator reads “0.023060070.” If the number is to have five significant figures, what result should you report? a)0.0230 b) 0.00231 c) 0.023060 d) 0.2367 e) 0.02306

  11. Answer • c) 0.023060 • 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.

  12. Question • How many significant figures are in the number 0.03040? a) One b) Two c) Three d) Four e) Five

  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.

  14. Question • Express 3140 in scientific notation. a) 3.14 × 103 b) 3.14 × 10−3 c) 3.140 × 103 d) 3.140 × 10−3

  15. Answer • a) 3.14 × 103 • 103 = 1000, and 3.14 × 1000 = 3140. 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.”.

  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 = 3.1415. d) A student walked 10 minutes to get to class.

  17. Answer • b) There are 60 seconds in a minute. • Quantities that are derived from the definition of a unit are exact numbers.

  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) 78.817 mL b) 78.82 mL c) 78.8 mL d) 79 mL

  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 26.42 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 26.4 + 26 + 26.42 = 78.82 mL, which must be rounded to 79 mL.

  20. Question • Which of the following is not an example of a derived quantity? a) Pressure b) Area c) Density d) Volume e) Length

  21. Answer • e) Length • Derived quantities are combinations of base units. Pressure is force per unit area (such as kg/(m.s2)), area is volume squared (such as m2), density is mass per unit volume (kg/m3), and volume is length cubed (such as m3).

  22. Question • Convert 5.853 kg to milligrams. a) 5.853 mg b) 5853 mg c) 5.853 × 106 mg d) 5.853 × 10−6 mg

  23. Answer • c) 5.853 × 106 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 • 103 g/kg x 103 mg/g = 106 mg/kg.

  24. Question • Ethylene glycol has a density of 1.114 g/mL. What volume must be poured into a graduated cylinder to give 21.1 g of ethylene glycol? a) 0.0528 mL b) 18.9 mL c) 18.94 mL d) 23.5 mL e) 23.51 mL

  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.

More Related