UNIT 1 EXTRA PROBLEMS FOR THE WEBSITE (Honors & Regents): Matter & Energy
1. Use scientific notation to express each number
a) 4,375 b) 186,000 c) 0.00012 d) 40.05
2. How many significant figures are there in each of the numbers in question #1?
3. The unaided eye can perceive objects which have a diameter of 0.1 mm. What is the diameter in inches? (2.54 cm = 1 in)
4. The density of alcohol is 0.80 g/mL. What is the mass of 50. mL of alcohol?
5. Calculate the density of a block of wood which weighs 750 kg and has the dimensions 25 cm x 0.10 m x 50.0 m.
6. The density of concentrated sulfuric acid is 1.85 g/mL. What volume of the acid would weigh 74.0 g?
7. A chemist dropped a 200. g object into a tank of water. It displaced 60. mL of water when it sank to the bottom of the tank. In a similar experiment, it displaced only 50. g of an oil into which it was dropped. Calculate the density of the object and the oil.
8. How many calories of heat must be added to 3.0 L of water to raise the temperature of the water from 20.0C to 80.0C?
9. Determine the quantity of heat required to convert 10. g of ice at 00C to vapor at 100.0C.
10. The freezing point of silver is 960.80C, and the freezing point of gold is 1063.00C. Convert these two readings to kelvin.
The following problems are for Honors only:
11. What is the volume in liters of a rectangular tank which measures 2.0 m by 50. cm by 200. mm?
12. A silver dollar weighs about 0.943 ounces. Express this mass in grams; kg; and mg. (1 oz = 28.35 g)
13. A piece of iron weighing 20.0 g at a temperature of 95.00 C was placed in 100.0 g of water at 25.00C. Assuming that no heat is lost to the surroundings, what is the resulting temperature of the iron and water? (specific heat of iron = 0.108 cal/g.0C)
14. Determine the heat required to raise 60. g of Pb from 20.0C to 360.0C, given its specific heats are 0.0306 cal/g.0C (solid) and 0.0375 cal/g0C (liquid). Its heat of fusion is 5.86 cal/g; its melting point is 3270C.
Answers: 1. (a) 4.375 x 103 (b) 1.86 x 105 (c) 1.2 x 104 (d) 4.005 x 101 , 2. [4; 3; 2; 4] , 3. 3.94 x 10-3 in , 4. 40.g , 5. 0.60 g/cm3 , 6. 40.0 mL , 7. [3.33 g/mL; 0.833 g/mL] , 8. 180,000 cal, 9. 7200 cal , 10. [1234 K; 1336.2 K] , 11. 2.0 x 102 L , 12. [26.73 g; 0.02673 kg; 26,730 mg] , 13. 26.50C , 14. 990. cal
The following is an example of an Honors test for Unit 1:
Multiple Choice:
1. When 20. calories of heat is added to 2.0 g of water at 15 degrees C, the temperature of the water (in degrees C) increases to:
a) 15 b) 50. c) 5 d) 25
2. Which substance can be decomposed by a chemical change?
a) helium b) argon c) ammonia d) iron
3. Which Kelvin temperatures represent, respectively, the normal freezing point and the normal boiling point of water?
a) 273 K and 373 K b) 0 K and 273 K c) 100 K and 273 K d) 0 K and 100 K
4. The graph to the right (get the diagram from Ms. Fed) represents the relationship between temperature and time as heat is added uniformly to a substance, starting as a solid below its melting point. During the BC portion of the curve, the average kinetic energy of the molecules of the substance...
a) decreases but the potential energy increases b) increases and the potential energy increases
c) remains the same and the potential energy decreases d) remains the same and the potential energy increases
5. At constant temperature, which 10 mL sample (at STP) will uniformly take the shape and volume of a 100 mL container into which it is placed?
a) mercury b) water c) carbon dioxide d) sodium chloride
6. Which temperature is the same as -13oC?
a) 747 K b) 773 K c) 286 K d) 260 K
7. Which phrase best describes the following reaction? ........ H2O (l) + energy ----> H2 (g) + 1/2 O2 (g)
a) exothermic, releasing energy b) endothermic, absorbing energy c) endothermic, releasing energy d) exothermic, absorbing energy
8. Which of the following substances is made up of particles with the highest average kinetic energy?
a) Br2 (l) at 20oC b) Fe (s) at 35oC c) H2O (l) at 30oC d) CO2 (g) at 25oC
9. At STP, which element is a solid?
a) argon b) carbon c) nitrogen d) hydrogen
10. Which process occurs when dry ice, CO2 (s), is changed into CO2 (g)?
a) sublimation b) crystallization c) solidification d) condensation
11. Which temperature represents absolute zero?
a) 273oC b) 0oC c) 273 K d) 0 K
12. The temperature of 50 g of water was raised to 50oC by the addition of 1000 calories of heat energy. What was the original temperature (in degrees Celsius) of the water?
a) 60 b) 30 c) 10 d) 20
13. The temperature of a sample of a substance changes from 10oC to 20oC. How many Kelvin degrees does the temperature change?
a) 283 b) 293 c) 10 d) 20
14. The temperature at which a substance in the liquid phase freezes is the same as the temperature at which the substance
a) sublimes b) boils c) melts d) condenses
15. Two different elements combine chemically to form substance X. This substance X must be....
a) a mixture b) a solution c) a compound d) an element
16. Which is NOT a form of energy?
a) motion b) heat c) temperature d) light
17. The temperature of a substance is a measure of the average ...
a) mass of its molecules b) kinetic energy of its molecules c) attractive force between its molecules d) potential energy of its molecules
18. An example of a chemical change is the
a) breaking of glass b) burning of gasoline c) boiling of water d) sublimation of moth balls
19. The heat of fusion for ice is 80 calories per gram. Adding 80 calories of heat to 1 gram of ice at STP will cause the ice to
a) increase in temperature b) decrease in temperature c) change to water at a higher temperature d) change to water at the same temperature
20. At which temperature would the molecules in a one gram sample of water have the LOWEST average kinetic energy?
a) 100 K b) 5oC c) -100oC d) 5 K
21. In the diagram at the right (get diagram from Ms. Fed) which represents a substance being heated from a solid to a gas under constant pressure, between B and C the substance exists in...
a) both the solid and liquid states b) neither the solid nor the liquid state c) the solid state only d) the liquid state only
22. Which phase change represents fusion?
a) gas to solid b) liquid to gas c) solid to liquid d) gas to liquid
23. A sample of water is heated from 10oC to 15oC by the addition of 30 calories of heat. What is the mass of the water?
a) 5 g b) 6 g c) 150 g d) 30 g
24. As a substance changes from a liquid to a gas, the average distance between tha molecules
a) decreases b) increases c) stays the same
25. When ice is melting, the temperature of the ice-water mixture remains constant because
a) heat energy is being converted to kinetic energy b) the ice is colder than the water c) heat is not being absorbed d) heat energy is being converted to potential energy
26. A combination of sand, salt, and water is an example of a
a) homogeneous mixture b) compound c) heterogeneous mixture d) pure substance
27. The elements calcium and fluorine combine to form the mineral fluorspar. The symbols for those elements are
a) K and F b) Ca and F c) Ca abd Fl d) Na and F
28. Which one of the following is an extensive property?
a) density b) shape c) boiling point d) freezing point
29. Round the number 0.07535 to two significant figures.
a) 0.08 b) 0.076 c) 0.0754 d) 0.075
30. 3 km2 is the same as _____ m2.
a) 3 x 106 b) 3 x 10-6 c) 3 x 104 d) 3 x 10-4
Problems: (pay attention to significant figures and include all units)
31. How much energy does it take to convert 0.50 kg ice at -20.0oC to water at 93.6oC? Specific heats: ice, 2.1 J/g.oC; liquid, 4.2 J/g.oC. Heat of fusion = 333 J/g
32. A piece of an unknown metal with mass 23.8 g is heated to 100.00oC and dropped into 50.0 mL of water at 24.0oC. The final temperature of the system is 32.50oC. What is the specific heat of the metal? (in J/g.oC)
33. Convert 4.8 yards/min to mm/s, using the Factor-Label method. (1 yard = 3 feet; 1 inch = 2.54 cm)
34. A team of students determined the density of a sample of wood to be 0.52 g/cm3. The Handbook of Chemistry and Physics reported a density of 0.548 g/cm3 for the same type of wood. What is the percent error of the students' value?
35. In the process of attempting to characterize a substance, a chemist makes the following observations: a) it melts at 649oC, b) its density at 20oC is 1.738 g/cm3, c) the substance reacts with chlorine to give a brittle, white solid, d) it can be pounded into thin sheets or drawn into thin wires. Which of these characteristics are physical properties and which are chemical properties?
a) _______________ b) ________________ c) _______________ d) __________________
36. A stock bottle of silver nitrate in the chemistry lab is filled with 462.2 g of that chemical at the beginning of that period. Successive students removed (with great care!) 22 g, 0.43 g, 58 mg, and 13.21 g. How much remains?
Answers:
1 d, 2 c, 3 a, 4 d, 5 c, 6 d, 7 b, 8 b, 9 b, 10 a, 11 d, 12 b, 13 c, 14 c, 15 c, 16 c, 17 b, 18 b, 19 d, 20 d, 21 a, 22 c, 23 b, 24 b, 25 d, 26 c, 27 b, 28 b, 29 d, 30 a.
(31) 3.9 x 105 J ,(32) 1.1 J/g.oC ,(33) 73 mm/s , (34) 5% , (35) physical, physical, chemical, physical , (36) 427 g.