UNIVERSITY PHYSICS I: ***PLEASE ANSWER AS MANY QUESTIONS AS POSSIBLE. I ONLY HAV
ID: 1615444 • Letter: U
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UNIVERSITY PHYSICS I:
***PLEASE ANSWER AS MANY QUESTIONS AS POSSIBLE. I ONLY HAVE 2 QUESTIONS LEFT FOR THIS MONTH
Chapter 19: THE KINETIC THEORY OF GASES - LECTURE REVIEW
1) Suppose your bicycle tire is fully inflated,with an absolute pressure of 7.00×10^(5) Pa(a gauge pressure of just under 90.0 lb/in^(2))at a temperature of 18.0ºC . What is the pressure after its temperature has risen to 35.0ºC ? Assume that there are noappreciable leaks or changes in volume.
2) The active ingredient in Tylenol is acetaminophen (C8H9NO2).Find the number of active molecules of acetaminophen in asingle 325 mg pill.
3) How many moles of gas are in the bike tire with a volume of 2.00×10^(–3) m^(3) (2.00 L), apressure of 7.00×10^(5) Pa (a gauge pressure of just under 90.0 lb/in^(2)), and at atemperature of 18.0ºC ?
4) (a) What is the average kinetic energy of a gas molecule at 20.0ºC (room temperature)?
(b) Find the rms speed of a nitrogen molecule N2 at this temperature.
5) What is the relative humidity whenthe air temperature is 25ºC and thedew point is 15ºC ?
6) Find the mean free time for argon atoms M = 39.9 g/mol at atemperature of 0°C and a pressure of 1.00 atm. Take the radiusof an argon atom to be 1.70×10^(10) m.
Chapter 20: THE FIRST LAW OF THERMODYNAMICS - LECTURE REVIEW
7) Studies of a van der Waals gas require an adjustment to the ideal gas law that takes into consideration that gas molecules have a definite volume. One mole of a van der Waals gas has an equation of state
(p+ (a/V^(2)) )(v-b)= RT,
where a and b are two parameters for a specific gas. Suppose the gas expands isothermally from volume V1 to volume V2. How much work is done by the gas during the expansion?
8) (a) Suppose there is heat transfer of 40.00 J to a system, while the system does 10.00 J of work. Later, there is heat transfer of 25.00 J out of the systemwhile 4.00 J of work is done on the system. What is the net change in internalenergy of the system?
(b) What is the change in internal energy of a system when a total of 150.00 J ofheat transfer occurs out of(from) the system and 159.00 J of work is done on the system?
Chapter 21: THE 2ND LAW OF THERMODYNAMICS - LECTURE REVIEW
9) A coal-fired power station is a huge heat engine. It uses heat transfer from burning coal to do work to turn turbines, which are used to generate electricity. In a single day, a large coal power station has 2.50×10^(14) J of heat transfer from coaland 1.48×10^(14) J of heat transfer into the environment.
(a) What is the work done by the power station?
(b) What is the efficiency of the power station?
(c) In the combustion process, the following chemical reaction occurs: C + O2 CO2 . This implies that every 12 kg of coal puts 12 kg + 16 kg+ 16 kg = 44 kg of carbon dioxide into the atmosphere! Assuming that 1 kg of coal can provide 2.5×10^(6) J of heat transfer upon combustion, how much CO2 is emitted per day by this power plant?
10) Suppose a nuclear power reactor has pressurized water at 300ºC. Steam, produced in the steam generator, is used to drive the turbine-generators. Eventually the steam is condensed to water at 27ºC and then heated again to start the cycle over. Calculate the maximum theoretical efficiency for a heat engine operating between these two temperatures.
11) What is the best coefficient of performance possible forsuch a heat pump, if it has a hot reservoir temperature of 45.0ºC and a cold reservoir temperature of 15.0ºC ?
12) Imagine a Carnot heat pump operates between an outside temperature of 0°C and an inside temperature of 20.0°C . What is the work needed if the heat delivered to the inside of the house is 30.0 kJ?
13) Spontaneous heat transfer from hot to cold is an irreversible process. Calculate the total change in entropy if 4000 J of heat transfer occurs from a hot reservoir at Th = 600K (327º C) to a cold reservoir at Tc = 250 K (23º C) , assuming there is no temperature change in either reservoir.
14) Entropy is directly related to the fact that not all heat transfer can be converted into work.
(a) Calculate the work output of a Carnot engine operating between temperatures of 600 K and 100 K for 4000 J of heat transfer to the engine.
(b) Now suppose that the 4000 J of heat transfer occurs first from the 600 K reservoir to a 250 K reservoir (without doing any work, producing the increase in entropy calculated above) before transferring into a Carnot engine operating between 250 K and 100 K. What work output is produced?
15) When ice melts, it becomes more disordered and less structured. The systematic arrangement of molecules in a crystal structure is replaced by a more random and less orderly movement of molecules without fixed locations or orientations. Its entropy increases because heat transfer occurs into it. Entropy is a measure of disorder. Find the increase in entropy of 1.00 kg of ice originally at 0ºC that is melted to form water at 0ºC.
Explanation / Answer
1 )
Pf = Po Tf / To
= 7 X 105 X 308 / 391
Pf = 7.41 X 105 Pa
2 )
C8H9NO2 = 151 g
325 X 10-3 / 151 = 2.15 X 10-3 moles
N = 2.15 X 10-3 X 6.023 X 1023
N = 1.3 X 1021 molecules
3)
V = 2.00 X 103 m3
P = 7.00 X 105 Pa
T = 273 + 18.0 = 291 K
P V = n R T
n = PV / R T
n = 7.00 X 105 X 2.00 X 103 / 8.314 X 291
n = 578662.0837 moles
4 )
KE = 3/2 k T
KE = 1.5 X 1.38 X 10-23 X 293
KE = 6.07 X 10-21 J
b )
m = 2 X 14.0067 X 10-3 / 6.023 X 1023
m = 4.65 X 10-26 kg
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