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Chemistry 1201 Section 4
Spring 1999
Professor Russo
Exam #1
Type of exam: Take-home. You can work with anyone on this exam, including me! You
better know how to do these problems, though. You will probably see similar problems again.
If this kind of material seems completely hopeless to you, you may wish to transfer to Chem
1001, then return to try 1201 another semester. Don't give up too easily; we will help you.
Due: Thursday, January 28 at the beginning of class.
100 points. Show your work neatly. We will not grade papers that just show an answer,
nor can we assign partial credit if we don't see the work.
________________________________________________________________________
Question #1. (BLB Text 1.12) In 1807 Humphry Davy passed an electric current through
molten potassium hydroxide and isolated a bright, shiny, reactive substance. He claimed the
discovery of a new element, which he named potassium. In those days, before the advent of
modern instruments, what was the basis on which one could claim that a substance was an
element? Be skeptical and critical like a good scientist.
Your answer must fit in this box!
Question #2. (related to BLB Text 1.24-c) The density of a piece of ebony wood is 1.20
g/cm3. What is the volume of 4.23 pounds of ebony wood? Express your answer in cubic
meters.
__________________
Put your answer here
Chem 1201 Sec. 4
Exam #1
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Question #3. (BLB Text 1.30-c) Mercury is a liquid metal that freezes at 234.28 K. What is
its freezing point in oF?
__________________
Put your answer here
Question #4. Someone tells you there are   107 seconds in one year. Compute the percent
error in this assessment.
__________________
Put your answer here
Question #5. (BLB #1.38) Carry out the following operations and express the answers with
the appropriate numbers of significant digits.
(a) 320.55 - (6104.5/2.3) = __________________________
(b) [(285.3  105)-(1.200  103)]  2.8954 = __________________________
(c) (0.0045 x 20,000.0) + (2813 x 12) = __________________________
(d) 863 x [1255 - (3.45 x 108)] = __________________________
Chem 1201 Sec. 4
Exam #1
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Question #6. This problem deals with how errors or uncertainties propagate from one
measurement to the next. A certain quantity used in the measurement of polymers is usually
given the Greek symbol, . The mass of the polymer molecules is proportional to the square of
this property--i.e., m  . Suppose that you measure  = 1.015  0.020 where the  indicates
the uncertainty of the measurement. (This is best obtained by repeating the measurements).
Based on the uncertainty in , what is the percentage uncertainty in the measurement of m?
__________________
Put your answer here
Question #7. (BLB Text 1.48) The maximum allowable concentration of carbon monoxide in
urban air is 10 mg/m3 over an 8-hour period. At this level, what mass of carbon monoxide in
grams is present in a room measuring 8  12  20 feet? (Hint: the 8 hour time span has
nothing to do with the answer). Show your work!
__________________
Put your answer here
Chem 1201 Sec. 4
Exam #1
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Question #8. (BLB Text 1.63-c) A brass sphere has a radius of 2.37 cm. If the density of
brass is 8.47 g/mL what is the mass of the sphere? (The volume of a sphere of radius R is
given by V = 4R3/3).
__________________
Put your answer here
Question #9. (BLB Text 1.64) An 8.47 g sample of solid is placed in a 25.00-mL flask. The
remaining volume in the flask is filled with benzene in which the solid is insoluble. The solid
and benzene together weigh 24.54 g. The density of the benzene is 0.879 g/mL. What is the
density of the solid?
25.00 mL ; Total mass: 24.54 g
Solid: 8.47 g
__________________
Put your answer here
Chem 1201 Sec. 4
Exam #1
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Question #10. Is ink an element, compound or mixture? Defend your answer briefly in the
box provided.
Your answer must fit in this box!
Chem 1201 Sec. 4
Exam #1
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