Questions/Problems Unit 2
Chemistry
10. Explain the conditions under which you would use the fire blanket versus the fire
extinguisher.
11. You see your lab partner rubbing her eyes during lab. What do you do?
12. Where are the fire extinguishers located in room 219?
13. You are heating a liquid in a 250 mL beaker and it catches fire. What do you do?
14. When are you allowed to take your safety goggles off during the lab period?
Mass Vol of Objects
160
140
Mass in g
120
Glycerol (l)
100
mercury(l)
80
Copper (s)
Oak (s)
60
Ethanol (l)
40
20
(l) = liquid
0
(s) = solid
0
5
10
15
Volume in mL
30. What is the most dense material shown above? What is its density?
31. Name the liquids in which copper will float:
32. Name the liquids in which Oak will float:
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33. What would be the mass of a 5.0 mL chunk of copper?
34. What would be the volume of a 60. g chunk of copper?
35. Steel alloy has a density of 7.8 g/mL. Sketch in its density line on the graph
above.
36. What is the density of a piece of concrete that has a mass of 8.76 g and a volume
of 3.07 mL? [2.85 g/mL]
37. Illegal ivory is sometimes detected on the basis of density. What is the density of
a sample of ivory whose volume is 14.5 mL and whose mass is 26.8 g? [1.85 g/mL]
38. An archeologist finds that a piece of ancient pottery has a mass of 0.61 g and a
volume of 0.26 mL. What is the density of the pottery? [2.3 g/mL]
39. Back of the previous problem. What would be the volume of an ancient vase of
mass 1.5 kg? Watch your units. [650 mL]
50. Little Johnny found a yellow substance that looked consistent throughout.
When it was burned in air the single gaseous product contained just two elements,
one of which was oxygen. Classify Johnny’s substance.
51. Salt water is consistent throughout, that is it is homogeneous. Explain why it is
NOT classified as a compound.
52. How would you classify milk?
53. Little Mildred found a solid white substance in her mother’s kitchen. She
vigorously heated it in the absence of air (don’t ask how!!) and found that it broke
down into different compounds. Classify Mildred’s substance.
54. Pure substance Z is melted and the liquid is placed in an electrolysis apparatus
similar to the Hoffman apparatus shown in class. When an electric current is passed
through the liquid, a black solid forms in one chamber and a white solid forms in the
other chamber. Is substance Z an element or a compound?
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55. When copper (II) sulfate is dissolved in an ammonia solution it combines with
the ammonia to form a beautiful blue material. Classify this new material. What is it
when it is dissolved in the liquid ammonia?
56. Steel is an made by dissolving some carbon in liquid iron followed by cooling.
Classify steel.
60. Back in the 80’s a cult leader named Jim Jones poisoned his entire group by
dissolving potassium cyanide in punch than forcing his followers to drink up. In this
situation identify the solute, solvent and solution.
61. Oil based paint can be removed from clothing using turpentine. In this situation
identify the solute, solvent and solution.
70. Identify each of the following as a physical or chemical property.
a. color
b. taste
c. reacts with zinc metal
d. density
e. tarnishes upon exposure to air
f. boiling temperature
71. Identify the following as physical or chemical changes:
a. Butter melting in a hot kitchen
b. Butter turning black after being placed into a hot skillet
c. Scrubbing burnt-on butter from a skillet with a steel wool pad.
d. Using oven cleaner to remove burnt-on butter from a skillet
e. Cooking down raw tree sap to make maple syrup
f. Grinding a steak with your teeth
g. Digesting a steak in your stomach and intestines
h. Adding hot water to coffee grounds to make some morning brew.
i. Acids produced by bacteria in plaque cause teeth to decay.
j. Adding Chlorox bleach to a red shirt to make it a pink shirt.
72. Aluminum can be melted then drawn into wire. Is this a chemical or physical
change?
73. When iron nails are used to secure a tin roof, the nails corrode away. Is this a
physical or a chemical change?
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80. An Alka-Seltzer of mass 2.00 grams is added to a flask with water. The mass of
the flask, cover and water is 142.00 grams. The tablet is placed into the flask then
tightly sealed. What will be the mass of the system after the tablet has completely
reacted?
81. 1.0 kg of nitroglycerine is detonated. An explosive such as this does not require
oxygen to explode. The result of the explosion gave 0.5 kg of carbon dioxide, 0.3 kg
of water vapor. How many kilograms of the third product, nitrogen dioxide, were
also produced?
82. If 114 grams of pure octane were to react with oxygen it would produce 352
grams of carbon dioxide and 162 grams of water. How many grams of oxygen must
have been consumed?
90. How much gravitational potential energy is stored in a cannon ball of mass 2.5
kg sitting on a fence post 2.0 m high? Assume the acceleration of gravity is 9.8 m/s2.
{49 J}
91. What is the kinetic energy of a 2.5 kg cannon ball rolling on the floor at 3.0 m/s?
{11.3 J}
92. How much potential energy is stored in a car of mass 1500 kg about to roll down
a hill of vertical distance 10.0 meters?
93. If this same car was rolling at 5.0 m/s, how much kinetic energy would it
possess? {18,750 J}
94. Why is kinetic energy called the “energy of movement”?
95. Still remember dimensional analysis? Try this: How much kinetic energy, in
Joules, does a bicyclist of mass 150 lbs have traveling at 10 ft/s? Assume 454 g =
1.00 lb and 2.54 cm/in {316 J}
110. Describe each of the following as an endothermic situation or an exothermic
situation:
a. Propane gas grill burning.
b. Exhaust coming from a turbo jet engine
c. Your body converting glucose to carbon dioxide and water.
d. Lighting 5 grams of glucose on fire and having it produce carbon dioxide
and water.
e. An ice cube melting.
f. The school nurse squeezes the two ingredients in a cold pack and starts the
reaction.
g. Aluminum is an excellent metal to recycle because it requires huge
amounts of energy to refine and produce new aluminum. Is the refining process
endothermic or exothermic?
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120. State the law of conservation of energy also known as the first law of
thermodynamics:
121. If the cannon ball in problem 50 were to fall from the fence post, how much
kinetic energy would it possess right before it hit the ground? What about when it
was 1.0 meter from the ground?
122. In the “Ring of Truth” video:
a. How was the energy input of the bikers measured?
b. What was a JDUnit?
c. Known energy outputs were rolling resistance and wind resistance. What
was the missing third energy output?
d. On a bicycle, what accounts for the largest energy output?
e. Name a cyclist who has won the Tour de France 7 times.
123. Give an example of converting kinetic energy to potential energy.
130. Suggest a reason why you can touch a piece of aluminum foil that has just come
from a hot oven and you will not burn yourself.
131. Suggest a reason why you would be severely burned if you tried to remove a
corning ware bowl from the same oven in problem 70.
132. Think of a situation in which some boiling water would have less heat in it than
cold water.
133. What does a thermometer directly measure, heat or temperature?
134. Explain why it costs more to heat a swimming pool from 20 to 25°C than water
at the same temperature in a 5 gallon bucket.
135. What is colder, a 1 cubic meter of ice at 0°C or a dead gray squirrel at 0°C?
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