Temperature, Thermal Expansion, and Ideal Gas Law The Density of copper is 8.9 E 3 kg/m^3 and each copper atom has a mass of 63 u, where 1u= 1.66 E -27 kg. Estimate the average distance between neighboring atoms. Answer: 2.3 E -10 m between atoms RoessBoss 1
Temperature, Thermal Expansion, and Ideal Gas Law Normal Body temperature is 98.6 degrees Fahrenheit. What is this on the Celsius Scale? Answer: 37.0 RoessBoss 2
Temperature, Thermal Expansion, and Ideal Gas Law A steel bed of a suspension bridge is 200 m long at 20 degrees Celsius. If the extremes of temperature to which it might be exposed are -30 degrees Celsius to + 40 degrees Celsius, how much will it contract and expand? Answer: 4.8 E -2 m and -12.0 E -2 m RoessBoss 3
Temperature, Thermal Expansion, and Ideal Gas Law An iron ring is to fit snugly on a cylindrical iron rod. At 20 degrees Celsius, the diameter of the rod is 6.445 cm and the inside diameter of the ring is 6.420 cm. To slip over the rod, the ring must be slightly larger than the rod diameter by about 0.008 cm. To what temperature must the ring be brought if the hole is to be large enough so it will slip over the rod Answer: 430 degrees Celsius RoessBoss 4
Temperature, Thermal Expansion, and Ideal Gas Law The 70 L steel gas tank of a car is filled to the top with gasoline at 20 degrees Celsius. The car is then left to sit in the sun, and the tank reaches a temperature of 40 degrees celsius. How much gasoline do you expect to overflow from the tank. Answer: 1.3 L RoessBoss 5
Temperature, Thermal Expansion, and Ideal Gas Law Determine the volume of 1.00 mol of any gas, assuming it behaves like an ideal gas A) at STP B) 20 degrees Celsius. Answer: 22.4 E -3 m^3 RoessBoss 6
Temperature, Thermal Expansion, and Ideal Gas Law Estimate the mass of air in a room whose dimensions are 5 m x 3m x 2.5 m high at 20 degrees Celsius Answer: 1600 mol RoessBoss 7
Temperature, Thermal Expansion, and Ideal Gas Law An automobile tire is filled to a gauge pressure of 200 kpa at 10 degrees Celsius. After driving 100 km, the temperature within the tire rises to 40 degrees Celsius. What is the pressure within the tire now. Answer: 333 kpa RoessBoss 8
Temperature, Thermal Expansion, and Ideal Gas Law Use Avogadro s number to determine the mass of a hydrogen atom. Answer: 1.67 E -27 kg RoessBoss 9
Kinetic Theory of Gases What is the average translational kinetic energy of molecules in an ideal gas at 37 C Answer: 6.42 E -21 J RoessBoss 10
Kinetic Theory of Gases Eight particles have the following speeds given in m/s: 1.0, 6.0, 4.0, 2.0, 6.0, 3.0, 2.0, 5.0. Calculate a) the mean speed b) the rms speed Answer: 3.6 m/s, 4.0 m/s RoessBoss 11
Kinetic Theory of Gases What is the rms speed of air molecules (Oxygen and Nitrogen) at room temperature (20 C) Answer: 480 m/s RoessBoss 12
Kinetic Theory of Gases On a particular hot day, the temperature is 30 C and the partial pressure of water vapor in the air is 21.0 torr. What is the relative humidity? Answer: 66% RoessBoss 13
Heat and The First Law of Thermodynamics How much heat is required to raise the temperature of an empty 20 kg vat made of iron from 10 C to 90 C B) what if the vat is filled with 20 kg of water Answer:720 kj, 6700kJ RoessBoss 14
Heat and The First Law of Thermodynamics If 200 cm^3 of tea at 95 C is poured into a 150 g glass cup initially at 25 C, what will be the final temperature T of the mixture when equilibrium is reached, assuming no heat flows to the surroundings. Answer: RoessBoss 15
Heat and The First Law of Thermodynamics How much energy does a refrigerator have to remove from 1.5 kg of water at 20 C to make ice at -12 C Answer:660 kj RoessBoss 16
Heat and The First Law of Thermodynamics At a party, a 0.50 kg chunk of ice at -10 C is placed in 3.0 kg of iced tea at 20 C. At what temperature and in what phase will the final mixture be? The tea can be considered as water Answer: 5.1 C RoessBoss 17
Heat and The First Law of Thermodynamics A) an amount of heat equal to 2500 J is added to a system and 1800 J of work is done on the system. What is the change in internal energy of the system Answer: RoessBoss 18
Heat and The First Law of Thermodynamics In an engine, 0.25 moles of gas in the cylinder expands rapidly and adiabatically against the piston. In the process the temperature drops from 1150 K to 400 K. How much work does the gas do? Assume the gas is ideal. Answer: 2300J RoessBoss 19
Second Law of Thermodynamics An automobile engine has an efficiency of 20 percent and produces an average of 23,000 J of mechanical work per second during operation. How much heat is discharged from this engine per second? Answer: 92,000 watts RoessBoss 20
Second Law of Thermodynamics A steam engine operates between 500 C and 270 C. What is the maximum possible efficiency of this engine? Answer: 0.30 RoessBoss 21
Second Law of Thermodynamics An engine manufacturer makes the following claims; the heat input per second of the engine is 9.0 kj at 475 K. The heat output per second is 4.0 kj at 325 K. Do you believe these claims. Answer: RoessBoss 22
Second Law of Thermodynamics A heat pump has a coefficient of performance of 3.0 and is rated to do work at 1500 W. A) how much heat can it add to a room per second? B) If the heat pump were turned around to act as an air conditioner in the summer, what would you expect its coefficient of performance to be, assuming everything remains the same. Answer: 2.0 RoessBoss 23