Examination 2. Multiple Choice Questions. Unit Conversions can be found at the End of the Exam. 1. The SI Unit standard for mass is the:

Transcription

1 CHEM 109 Introduction to Chemistry Fall 2015 Name: Answer Key Examination 2 Multiple Choice Questions Unit Conversions can be found at the End of the Exam. 1. The SI Unit standard for mass is the: a) Pound (lb) b) gram (g) c) slug (sl) d) kilogram (kg) ***** 2. What quantity is measured using the following unit? cubit 2 a) length b) volume c) area ***** d) mass 3. Perform the following unit conversion: 3.5 x 10 2 L =? nl a) 3.5 x nl b) 3.5 x 10-7 nl 3.5 x 10 2 L (1 nl / 10-9 L) = 3.5 x nl c) 3.5 x nl d) 3.5 x nl ***** 4. Perform the following unit conversion: 3.1 x 10 4 mg =? dg a) 3.1 x 10 2 dg ***** b) 3.1 x 10 1 dg 3.1 x 10 4 mg (10-3 g / 1 mg) (1 dg / 10-1 g) = 3.1 x 10 2 dg c) 3.1 x 10-1 dg d) 3.1 x 10-2 dg

2 5. The fifth was once the usual size of bottles of distilled spirits; a volume opf 1/5 gallon. Liquor is now sold in bottles of 750 ml. What is 1/5 gallon in milliliters? a) 763 ml b) 761 ml 1/5 gal (4 qt / 1 gal) (1 L / qt) (1 ml / 10-3 L) = 757 ml c) 759 ml d) 757 ml ***** 6. Sound travels at 5.4 x 10 3 cm/s through Rubber. How long will it take sound to travel across a rubber block 3 meters across? a) s ***** b) 0.32 s 3 m (1 cm / 10-2 m) = 300 cm c) 1.7 s d) 24. s 300 cm / (5.4 x 10 3 cm/sec) = sec 7. Lead has a density of g/cm 3. What is the mass of a rectangular block of Lead 2.5 cm x 5.0 cm x 10.0 cm? a) 9.8 x 10-1 g b) 2.7 x 10 1 g V = 2.5 cm x 5.0cm x 10.0 cm = 125 cm 3 c) 4.1 x 10 2 g d) 1.4 x 10 3 g ***** m = d x V (11.34 g/cm 3 ) (125 cm 3 ) = 1.4 x 10 3 g 8. Which of the following measurements will not be useful in identifying a substance? a) density b) mass ***** An extensive physical property. c) color d) melting point 9. An Oil-Water system is a: a) Heterogeneous system. ***** 2 phases are present. b) Homogeneous system. c) Solution. d) Pure Substance.

3 10. Vacuum filtration is usually used when one wants to: a) separate and purify a liquid from a solid. b) separate and purify a solid from a liquid. ***** c) separate two solids from each other. d) separate two liquids from each other. 11. Which of the following is not a solution: a) Salt-Water. b) Air. c) Crude Oil. d) Grain Alcohol. ***** 12. Attached is a paper chromatogram of sever naturally occurring oils: How many components does Oil L contain? a) 1 b) 2 c) 3 ***** d) 4

4 13. When Water is electrolyzed, two colorless gases are given off in a two-one proportion. This experiment tells us: a) the gases are both compounds. b) the gases are both elements. c) nothing about the elemental nature of the gases. ***** 14. An Oil-Water system can be separated by: a) filtration. b) using a separatory funnel. ***** c) distillation. d) paper chromatography 15. A mixture of Kerosene and Gasoline, both petroleum products, can be separated by: a) filtration. b) using a separatory funnel. c) distillation. ***** d) paper chromatography 16. The element Cesium (Cs) is a: a) non-metal solid. b) non-metal liquid. c) metal liquid. d) metal solid. ***** 17. Oxygen(O), Sulfur(S), and Selenium (Se) are grouped together because they: a) have the same boiling point. b) react chemically in a similar manner. ***** c) are all gases. d) are all metals.

5 Short Answer Questions 1. Discuss the progression of events in the establishment of the meter as a unit standard. Your discussion should address the following questions: i) Why did the French Academy of Sciences promote the establishment of the meter? ii) What was the original definition of the meter? iii) Why was the provisional meter established? iv) Why did we move away from the 1875 meter standard; two marks on a Pt-Ir bar? v) In very general terms, how is the current meter defined? At the time the Academy recommended the establishment of the meter, many different units were in use throughout France and they wanted to replace these many units with a single unit standard for each quantity to be measured. Originally the meter was defined as 1/10,000,000 of the distance between the Pole and the Equator along a meridian running through Paris. A provisional meter was established to be used while the survey was being conducted to determine the length of the meter. The 1875 definition of the meter was abandoned because too many factors, such as temperature, affected the length of the Pt-Ir bar used in the definition. The current definition of the meter is the distance light travels in a specified period of time.

6 2. In the "Chemical Families" movie, we saw that Fluorine, Chlorine, Bromine and Iodine form a chemical family called the Halogens. Generically, what criteria are used to arrange elements into a chemical family? Elements are arranged into "families" according to similar chemical reactivities and physical properties. 3. Provide an example of a colloid. What phases are involved in your colloid? Milk, an emulsion with a liquid dispersed into a liquid. 4. How can you separate Potassium Nitrate and Cupric Sulfate from each other? (Think back to an experiment we did in the laboratory.) Dissolve the mixture into Water. Boil off Water until the Potassium Nitrate crystals begin to precipitate. Then cool the liquid until the Potassium Nitrate crystallizes fully. Then filter off the Potassium Nitrate crystals. 5. The heavy element Francium does not occur naturally. Why is this? Francium is a radioactive element that very rapidly transmutes into lighter elements. It is prepared in a nuclear reaction by fusing lighter elements together.

7 6. An automobile engine has a displacement of 305 cubic inches. What is its displacement in liters? 305 in 3 x (2.54 cm/1 in) 3 x (1 ml/1 cm 3 ) x (10-3 L/1 ml) = 5 L 7. Consider the elements of the 4 th Period of the Periodic Table of the Elements; the 4 th row of the Table. What is the trend in metallic character (metal to non-metal or vice versa) as one goes across this Period from left to right? Provide two examples that support your contention. Left to right the metallic character decreases. The leftmost element in the Period is Potassium (K) a metal. The rightmost element is Krypton (Kr), a non-metal.

8 Unit Conversions Length Mass Temperature 1 in = 2.54 cm 1 kg = lb K = o C mi = 5280 ft 1 lb = 16 oz o C = ( o F - 32) 1 ft = 12 in 1 amu = x kg 1 yd = 3 ft 1 cubit = 18 in 1 ell = 45 in o F = o C + 32 Volume Energy Pressure 1 L = 10-3 m 3 1 cal = J 1 atm = Pa 1 L = qt 1 ev = x J 1 atm = 760 Torr = 760 mmhg 1 gal = 4 qt 1 bar = 10 5 Pa 1 qt = 2 pt 1 J = 1 kg m 2 /s 2 1 psi = Pa 1 pt = 16 oz 1 ml = 1 cm 3 1 Pa = 1 N/m 2 = 1kg/m s 2