Key Quiz 1

1) How many significant figures are in each of the following values?

1000.10 0.003702 1.03 x 103 4.2010 1.003702

6, 4,3,5,7

2) Write down the proper answer with the right number of significant figures

((2.70/3.00) -2.0) x (1.20) = 0.900 -2.0 = -1.1x1.20 = -1.3

2.5/2.0 = 1.125 = 1.12

(2.45/2.0) - 0.5 = 1.2 -0.5= 0.7

3.11 - 6.829 = -3.72

3) A cylindrical glass tube 30.0 cm in length is filled with ethanol. The mass of ethanol needed to fill the tube is found to be 19.28 g. Calculate the inner diameter of the tube in millimeters. (The density of ethanol is 78.9 g/dL.) V= p r2 l

Answer 19.28g / 0.789g/mL =V =24.4mL =24.4 cm3 /30.0cm =0.813 cm2 / p = r2 =0.259 r=0.509 d= 1.018 è 1.02 cm è 10.2 mm

4) Do the following conversions:

10.0 inches = / 254 / mm 10*2.54*10
1 ton = / 907.2 / Kg 2000*453.6/1000
12.5 gallons = / 47.3 / L 12.5*3.785
100.00 oF / 310.93 / K (5/9)*(F-32) + 273.15

5) What are the benchmarks that define the Celsius and Kelvin Temperature Scale? What happens at Absolute Zero?

Melting Point 0 and Boiling Pt (100) of water è Celsius

Absolute Zero 0 K == - 273.15 C all chemistry stops (no translational motions) but vibration motion continues and electron and nuclear motion continue.

6) What if the benchmarks were the BP/MP of methane which are -182.5 C and -161.7 C at one atmosphere. What would be the conversion relationship between MethaneScale (MS) and Celsius.

C= (20.8/100)*MS-182.5

To chedk: if MS =0 then C=-182.5 if MS=100 then C=20.8(100/100)-182.5=-161.7

7) An unhealthy person has about 209. mg of cholesterol per dL of blood. If the total blood volume of that individual is 5.74 L, how many grams of total blood cholesterol does the individual contain?

12.0 grams (209x10-3)g /10-1L x 5.74L =11.996g = 12.0 g

8) Water unlike most materials reaches its maximum density of 1.000 g/cc at 4oC at which point its density slightly decreases while being cooled to where its density is 0.9998 g/cc as a liquid. However when it solidifies its density drops dramatically to 0.917 g/cc at this same temperature oC. For the same mass of H2O how does the volume of the material change as it is cooled from room temperature down to below the 0oC? How does this affect its physical properties?

The volume decreases until it reaches 4C and then slightly increases as a liquid down to 0C at which point it turns to a solid and fairly uniquely then increases dramatically. This increase in volume results in a lower density due to higher order of molecules and the lower density results in ice floating in liquid water (unusual phenomena)

9) A block of ice is 5 inch on a side at 0 C is heated to 20C (r =0.99823 g/ml), what is the mass and volume of the liquid in ml?

(5in)3 = 125 in3 x (2.54cm)3 /1 in3 = 2048.38 cm3 *0.917 g/cc = 1878.37g same for Liquid/Solid

1878.37g * (1ml /0.99823g) = 1881.7 ml which is also cm3

10) Design a circular coin worth $1000 dollars. Conventional thickness of coins varies from 1.3-2 mm. Since gold is pliable let make it 2.00mm What would need to be the size of the coin in inches?

Price of Gold today is $40.03/gram (Note difference Troy vs US ounces)

24 carat is 100% gold, 18 carat is 75%

Density of Gold = 19.30g/cm3

$1000.00 x (1g/$40.03) = 24.98 g of Gold needed

24.98g * (1cm3/19.30g) = 1.294 cm3 is the need Volume of the coin

1.294 cm3 = p r2 (0.20cm)

r 2 = 2.06 cm2 è r = 1.44 cm

d= 2.88 cm 1.13 in in diameter