Chemistry 100 –Chemistry Today

Exam 1 (April 12, 2002)

Questions 1 - 6 (24 points) are multiple choice questions. There will be no partial credit given for these problems. Problems 7 - 10 (16 points) are short response questions. Problems 11-20 (60 pts) should be worked out on the exam and partial credit will be given for work shown. In these last sets of problems, the answer by itself is not satisfactory for full credit.

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There is a blank page at the end of this examination for use as scratch paper.

INFORMATION THAT MAY BE OF USE TO YOU IN THE EXAM.

0.62 mile = 1 km1 in ≡ 2.54 cm

1 L = 1.06 qts

Periodic Table

Name:

1.(4)What question can we ask in order to distinguish between a theory and a law?

a.Does the statement concern atoms?

b.Does the statement concern gases?

c.Is the statement comprehensible?

d.Is the statement measurable?

e.none of the above.

2.(4)What physical quantity is expressed by the metric unit milliliter?

a.length

b.mass

c.volume

  1. density
  2. none of the above

3.(4)According to the metric system, 1 m = 1000 ___

a.cm

b.cm3

c.km

d.mm

e.none of the above

4.(4)Which of the following can be separated into two or more pure substances using a physical method?

a.compound

b.element

c.mixture

  1. all of the above
  2. none of the above

5.(4)Refer to a periodic table and predict which of the following elements is a gas at 25C and one atmosphere pressure?

  1. Na
  2. Nb
  3. Nd
  4. Ne
  5. Np
  1. (4)According to the conservation of mass and energy law, which of the following is true of a nuclear fusion bomb?
  1. The mass of the bomb and the fusion products are identical
  2. The energy of the bomb and the fusion products are identical
  3. A small amount of matter is converted into energy
  4. All of the above
  5. None of the above
  1. (4) State the number of significant digits in each of the following:
  2. 2.50 cm
  1. 0.0032 g
  1. $6,024,288,000,000 is the US national debt
  1. the answer to 242.167 g minus 175 g

8. (4)Classify each of the following as a physical or chemical change.

  1. Touching a match to methane soap bubbles and seeing a flame
  1. Heating water in a flask produces moisture on the glass
  1. Grinding aspirin tablets produces a powder
  1. Adding together two colorless solutions gives a deep pink solution

9. (4)Identify two forms of energy that are involved in a lead-acid battery

10. (4)Write the name of the element or the symbol for each of the following elements

  1. P
  1. Fe
  1. gold
  1. nickel

Show your work on all problems!

  1. (4)The freshman class this year was 444 strong. This year 80 students were enrolled in CHM 100 and 83 students were enrolled in CHM 113. Assuming these students were all freshmen, what percent of the freshman class enrolled in beginning chemistry courses this year?

12. (4)If a mineral water bottle contains 375 mL, what is the volume in quarts?

13.(6)If an automobile engine is 155 in3, what is the volume in L?

14. (8)How many minutes are required for sunlight to travel from the Sun to the Earth? (Assume the Sun is 93,000,000 miles from Earth and that sunlight travels at 3.00 x 108 m/sec.)

15. (4)If 2.43 g of magnesium are burned in oxygen to produce 4.03 g of magnesium oxide, what is the mass of reacting oxygen gas?

16. (6)What is the total number of each kind of element (C, H, O) in stearic acid, CH3(CH2)16COOH?

17. (6)If a steel cylinder of helium gas is cooled from 50C to 0C, does the kinetic energy and motion of helium atoms increase or decrease? Explain.

18. (6)Is the weight of an astronaut more, less, or the same on Pluto as on Mars? The mass of Pluto is 1.27 x 1022 kg, and that of Mars is 6.42 x 1023 kg. Explain.

19. (10)I found two gold colored metals and was wondering if they were the same material. One weighed 86.85 g and was cylindrical in shape. I put it into a graduated cylinder that contained 26.5 mL of water and the water level rose to 31.0 mL. The other piece was in the shape of a block and weighed 5.60 g and had the dimensions of 0.5 cm x 0.5 cm x 2.5 cm. Are these the same metals?

20.(6)In lab you compared the densities of the plastics to the densities of three solutions (water, sugar water, and alcohol). The densities of these are 1.00 g/mL, 1.10 g/mL, and 0.93 g/mL respectively. If a plastic from a milk jug has a density of 0.96, tell me if the plastic would sink or float when placed in each of the three solutions.