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Math & Measurement
Assignment
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![]() 11th Edition |
![]() 12th Edition |
Instructions are given for both the 11th Edition of the textbook and the 12th Edition. |
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Temperature: Read what the book says about temperature and the three scales used for temperature. Learn how to convert between the three scales. Notice that the book gives you names of the three scales, (Fahrenheit, Celsius, & Kelvin) but does not explain how these names came about or the how the temperature scales were created. I feel that if you don't know this background information, there will always be a hole in your learning. I will cover temperature in a separate tutorial, but if I didn't, you should do your own background check. |
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Density: 11th Edition, page 35: Density can be calculated with simple measurements-volume and mass. Read Section on Density |
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The book shows both the algebraic approach and the Dimensional Analysis approach. Trust me, the Dimensional Analysis will be easier in the long run, so focus on that approach. They use parentheses to indicate multiplication, but as I've shown before, a faster way to write it is with vertical lines. |
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Book Example 2.23: Here is my suggested style. Write the 25mL as the starting amount and the grams as the end dimensions. The density is given as 19.3 g/mL. These dimensions are good because the grams stays and the mL cancels out the mL in 25.0 mL. |
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If this problem said, "You have 483 grams of gold. What is the volume?", then the 483 grams would be written first and the density would be written upside down (1 mL/19.3grams) so that the grams cancels out and the mL stays. The answer would be 25.0 mL. |
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Gold Density Problem 1: The first part of this problem is to solve for the volume of the bar. They give you the dimensions of the bar. Realize the volume of a rectangular solid (a bar) is V=L x W x H (length x width x height). Use the density of gold mentioned above and dimensional analysis to convert the volume of the bar into grams. Compare the calculated grams to the 3300 grams that it actually weighed. (a) What should it have weighed if it were pure gold? (b) Was it pure gold and why? |
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Gold Density Problem 2: The problem says to use the current price of $559 per
oz (troy oz); however, look up the current price of gold on the Internet
and then use that price. They give a conversion of 14.58 troy oz = 1 pound.
You will also need to know that 2.2 lbs = 1 kg = 1,000 g. |
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Problem #3: In the textbook they show this graphic to explain density.
What's nice they drew the boxes to scale. In other words, the sulfur box
measured about 1.7 centimeters (cm) on each side. That gives the volume
of 1.7cm x 1.7cm x 1.7cm = 4.9cm3, which is close to the volume
they show for sulfur. |
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Oil Slick Problem example: This is a bit tricky problem. The slick is considered
a very flat box with a volume equal to W x H x L. Volume is 200cm3(about a cup full).
Height is 0.5nm (about 1/200 of human hair) and the width and length are the same size, let's call
them M. |
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With dimensional analysis we put our starting amount on the left and what we want to find on the right. Realize that cm3 is cm x cm x cm. cm3 has "m" three times (cubic meter); however, our answer is square meters (m2). So that means we have to get rid of one of the meters (m). That's why the 0.5nm (nanometers) is on the bottom. The meter in "nm" will cancel one of the meters in the cubic centimeters. Then we end up with the meters squared (m2) that we want. The starting amount also has "centi" (c) three times, so we cancel them by multiplying by 0.01 over "c" three times. Remember c=0.01. Then "n" in 0.5nm needs to be canceled so we put "n" on top and its equivalent on the bottom (10-9, which is one billionth). If dimensions are in the right place, everything that needs to cancel will cancel and you are left with the correct final units (m2). Now we just multiply all of the numerators together and divide by each of the denominators. So the 200cm3, which is less than a cup of oil, can form an oil slick that covers 400,000 m2, which is the area of about 100 football fields. |
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Problem #4: Here is a picture of the Exxon Valdez. It spilled 11 million gallons of oil. How many square miles of ocean could it cover if the oil also coated the surface also with 0.5nm thickness of oil? Setup the problem the same as before except there will
need to be more conversions. If you can do this problem, count yourself
very smart. |
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| email your answers to me at chm130@chemistryland.com | ||
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