Chemistry 1001
Recitation Topics #6 for
Come to recitation prepared to discuss each problem quickly; a quiz might follow, and problems like these are fair game for exams.
One thing to notice about this Recitation Topic: it’s a mixture of old and new material. Gotta get you ready for the final exam, which is cumulative!
Another thing to notice: we are making you combine concepts now.
_____________________________________________________________
Page 1

1. The isotope
2
1
H is known as deuterium, a form of hydrogen. In chemical formulae, it is usually just given the symbol D. For example, deuterated water is D
2
O. Consider perdeuterated (i.e., completely deuterated) methanol, CD3OD. Compared to normal methanol, CH
3
OH, the density of CD
3
OH is:
Less The Same More
Circle One molecules?)
Briefly explain your reasoning. (Hint: what takes up space in atoms &
Page 2

2. We will hydrolyze water by dropping a battery into brine. Besides hydrogen and oxygen, this will make quite a mess! How would you normally dispose of a 9-volt battery and will it make such a mess as we shall see?
Page 3

3. Stephanie weighs 145 lbs. If she develops a fever that raises her body temperature to 102°F, that must take quite a lot of energy! She is either producing too much heat or failing to dissipate it. Estimate the heat required
(in calories and Joules) to raise her temperature to 102°F. You can make assumptions, but you must state them clearly and justify them.
Assumption: ________________________________________
Justification:______________________________________
Assumption: ________________________________________
Justification:______________________________________
Assumption: ________________________________________
Justification:______________________________________
________________Calories
_________________Joules
Page 4

4. In very cold, dry climates, snow can disappear even though it never melts. Explain.
(The obvious answer--it blows away--is too easy, although that certainly is part of the reason why the snow goes away).
I lived here for awhile.
See it in summertime.
Page 5

5. Under typical voltages as used in the home, electrons move rather slowly in a wire-e.g., about 2.5

10
-4 m/s. This is called "drift velocity". If you turn on a light switch, compute the time (in minutes) it takes an electron to travel from the switch to a light bulb located 20 feet down the wire and across the room.
____________minutes
Page 6

6. In the previous problem, you should have gotten a pretty long time. How come the light turns on so quickly then?
7. Actually, the electrons in a home wiring circuit just jiggle back and forth 60 times a second (60 Hz) and they would never travel 20 feet. (The electrons in the wires of your house are the same ones that have been there for years, despite all the money you have sent to the power company!) This is because we use alternating current (AC) power instead of direct current (DC). In our 60 Hz power supply system, how far do electrons drift leftward before they reverse course and drift rightward.
Page 7

b) a) c)
8. Explain the following observations in terms of where electrons are found in covalent, as opposed to metallic, materials: a) People can walk on hot coals, but you rarely see them walk on hot frying pans. b) You can touch your tongue to a tree on a freezing cold day, but if you try the flagpole, your tongue will stick to it rather quickly and someone will have to call a rescue squad. (I know, not fair--there are never any cold days in Louisiana, but it is no wives’ tale that your tongue can get stuck if touched to cold metal, as in the movie, “Christmas Story”: http://www.youtube.com/watch?v=pFu7SjF7Hfg ) c) Plastics exist that can be brought to very high temperatures (enough to hold molten aluminum, for example) but the plastic "branding iron" is not a big success.
Page 8

9. A list of record cold temperatures by state appears on the next page (taken from: http://www.usatoday.com/weather/wcstates.htm
). Convert any five of the temperatures to
Kelvin and Celsius (centigrade) without a calculator, using the tricks we showed in lecture. Show how you do it in the box below for our warmest and coldest states. How would you do it quickly for all 50 states? Your TA will demonstrate!
Here’s what it says in my spreadsheet cell for one conversion:
_______________________
The coldest state is _________ and that’s ____________°C or ________________K
The warmest state is _________ and that’s ____________°C or ________________K
Page 9

State
Alabama
Alaska
Arizona
Arkansas
California
Colorado
Connecticut
Delaware
Florida
Georgia
Hawaii
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Louisiana
Maine
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Montana
Nebraska
Nevada
New Hampshire
New Jersey
New Mexico
New York
North Carolina
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont
Virginia
Washington
West Virginia
Wisconsin
Temp. Date Station
( oF)
-27 Jan. 30, 1966 New Market
-80 Jan. 23, 1971 Prospect Creek
-40 Jan. 7, 1971 Hawley Lake
-29 Feb. 13, 1905 Pond
-45 Jan. 20, 1937 Boca
-61 Feb. 1, 1985 Maybell
-32 Feb. 16, 1943 Falls Village
-17 Jan. 17, 1893 Millsboro
-2 Feb. 13, 1899 Tallahassee
-17 Jan. 27, 1940 N. Floyd County
12 May 17, 1979 Mauna Kea
-60 Jan. 18, 1943 Island Park Dam
-36 Jan. 5, 1999 Congerville
-36 Jan. 19, 1994 New Whiteland
-47 Feb. 3, 1996* Elkader
-40 Feb. 13, 1905 Lebanon
-37 Jan. 19, 1994 Shelbyville
-16 Feb. 13, 1899 Minden
-48 Jan. 19, 1925 Van Buren
-40 Jan. 13, 1912 Oakland
-35 Jan. 12, 1981 Chester
-51 Feb. 9, 1934 Vanderbilt
-60 Feb. 2, 1996 Tower
-19 Jan. 30, 1966 Corinth
-40 Feb. 13, 1905 Warsaw
-70 Jan. 20, 1954 Rogers Pass
-47 Feb. 12, 1899 Camp Clarke
-50 Jan. 8, 1937 San Jacinto
-47 Jan. 29, 1934 Mt. Washington
-34 Jan. 5, 1904 River Vale
-50 Feb. 1, 1951 Gavilan
-52 Feb. 18, 1979* Old Forge
-34 Jan. 21, 1985 Mt. Mitchell
-60 Feb. 15, 1936 Parshall
-39 Feb. 10, 1899 Milligan
-27 Jan. 18, 1930 Watts
-54 Feb. 10, 1933* Seneca
-42 Jan. 5, 1904 Smethport
-25 Feb. 5, 1996 Greene
-19 Jan. 21, 1985 Caesars Head
-58 Feb. 17, 1936 McIntosh
-32 Dec. 30, 1917 Mountain City
-23 Feb. 8, 1933* Seminole
-69 Feb. 1, 1985 Peter's Sink
-50 Dec. 30, 1933 Bloomfield
-30 Jan. 22, 1985 Mountain Lake
-48 Dec. 30, 1968 Mazama
-37 Dec. 30, 1917 Lewisburg
-55 Feb.4, 1996 Couderay
1,720
6,525
1,929
800
958
4,700
1,500
700
5,470
3,700
5,200
6,288
70
7,350
425
3,100
2,277
2,471
3,275
8,092
915
3,870
2,120
2,200
1,300
Elevation Temp.
(feet) (oC)
760
1,100
8,180
1,250
5,532
5,920
585
20
193
1,000
13,770
6,285
722
785
770
1,812
730
194
458
2,461
640
785
1,430
420
Temp.
(K)
Page 10

10. Life is full of conflict. At my home, Supreme Command has determined that butter belongs on the counter—that is, outside the refrigerator. So, if I butter a soda cracker, it’s just yellow goo on top. Yuck. Epicures know that butter is intended to be kept chilled, so it remains solid on your cracker. After 37 years of wedded bliss, a compromise has been reached….I now have my own little container of butter kept in the fridge. It’s a miracle.
But what should I use to spread the butter, a metal knife or a plastic knife? Why?
Page 11

11. One summer, I attempted to climb a mountain. The official starting elevation was 9450 ft, the ending elevation was 13,335 feet. Unfortunately, I had to park a distance away from the trail head…an uncertainty in the starting elevation of 
75 feet. Also, I didn’t quite make it to the top (I’m blaming a hail storm, but bad planning had something to do with the failure, too). I got to 13,200

55 feet before wimping out. Now, my weight is 180

3 pounds (I am lying). a. What energy in calories is required for the climb? (
W = m·a·d where a = acceleration = gravity = 9.8 m·s -2
).
Energy = ____________

_________calories b. How many candy bars is this, if a candy bar provides 270 Calories (i.e., 270,000 calories). You can ignore the

part here, but think about it anyway.
Number of candy bars: _____________ c. If a friend tells you he is going to lose weight by exercise, without altering his eating habits, what do you say?
Page 12