im a freshman in physics and i need help answering 5 questions out of these 6. please help
1.)A confined sample of an ideal gas is heated so that its temperature rises from 20°c to 100°c. Its initial pressure is 1 atmosphere. Find its final pressure.
2.)Explain how heat may be added to a gas while its temperature (and internal energy) do not increase?
3.)A gas absorbs 300J of heat and does 100J of work. By how much does its internal energy increase?
4.)A heat engine takes in 300J of heat while doing 100J of useful work. What is its efficiency? How much heat does it exhaust to the environment?
5.)Find the number of moles in a 600ml soda bottle at STP b) After heating up 20kevlin, what is the new pressure?
6.)A heat engine absorbs 200J of energy from a hot reservoir at 800K and expels 110J of energy to a sink at 300K. Calculate the ideal and actual efficiencies of the engine.
1.)A confined sample of an ideal gas is heated so that its temperature rises from 20°c to 100°c. Its initial pressure is 1 atmosphere. Find its final pressure.
2.)Explain how heat may be added to a gas while its temperature (and internal energy) do not increase?
3.)A gas absorbs 300J of heat and does 100J of work. By how much does its internal energy increase?
4.)A heat engine takes in 300J of heat while doing 100J of useful work. What is its efficiency? How much heat does it exhaust to the environment?
5.)Find the number of moles in a 600ml soda bottle at STP b) After heating up 20kevlin, what is the new pressure?
6.)A heat engine absorbs 200J of energy from a hot reservoir at 800K and expels 110J of energy to a sink at 300K. Calculate the ideal and actual efficiencies of the engine.
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Hello there. I will help you with these.
1) Use something called combined gas law. It goes like this (P1V1/T1)=(P2V2/T2) In this case, your volume is constant. So the equation will turn into P1/T1=P2/T2. Turn temperature into Kelvin (add 273) so you get (1atm/293K)=(x atm/ 373K). solve for x you get 1.273 atm.
2)Expand the volume while adding in heat. This will cause increase the size of the container and maintain the frequencies that the particles hit each other.
3)This is an easy one. 300-100=200J.
4)100J is used. So 100/300=33% efficiency. the other 200J is wasted, aka the exhaust.
5)STP means 273 kelvin and 1 atm. PV=nRT (1atm)(0.6L)=n(.0821)(273K). Solve for n you get .0268 moles. b) (x atm)(.6L)=(.0268moles)(.0821)(293K). Solve for x you get : 1.073atm.
6)Ideal efficiency (carnol efficiency) = (Thot-Tcold)/Thot. so (800-300)/800=.625=62.5% efficiency.
In the real world its different. Real efficiency = work/ Heat(hot) = 110J/200J=.55=55% effciency. This is way too high to exist in real life but its a book problem.
Hope this helped. Good luck
1) Use something called combined gas law. It goes like this (P1V1/T1)=(P2V2/T2) In this case, your volume is constant. So the equation will turn into P1/T1=P2/T2. Turn temperature into Kelvin (add 273) so you get (1atm/293K)=(x atm/ 373K). solve for x you get 1.273 atm.
2)Expand the volume while adding in heat. This will cause increase the size of the container and maintain the frequencies that the particles hit each other.
3)This is an easy one. 300-100=200J.
4)100J is used. So 100/300=33% efficiency. the other 200J is wasted, aka the exhaust.
5)STP means 273 kelvin and 1 atm. PV=nRT (1atm)(0.6L)=n(.0821)(273K). Solve for n you get .0268 moles. b) (x atm)(.6L)=(.0268moles)(.0821)(293K). Solve for x you get : 1.073atm.
6)Ideal efficiency (carnol efficiency) = (Thot-Tcold)/Thot. so (800-300)/800=.625=62.5% efficiency.
In the real world its different. Real efficiency = work/ Heat(hot) = 110J/200J=.55=55% effciency. This is way too high to exist in real life but its a book problem.
Hope this helped. Good luck
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Don't complicate things. Its just memorizing the equations and plug in the values.
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