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In an experiment of combustion a mixture of gasoline and oxygen ina"pump" at constant volume, surrounded by water. Duringtheexperiment it is observed that the water´s temperatureincreases.If we consider the mixtures of gasoline and oxygen asthesystem:

i) Has been there heat transferred?

ii) Has been there work performed? What is the sign forΔU?Explain

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Physics: Principles with Applications
7th Edition, 2013
Giancoli
ISBN: 9780321625922

Related questions

A liquid has been irregularly agitated in a insulated recipientandit is observed that its temperature (of the liquid ) increases.Ifwe consider the liquid as the system:

a) has been there heat transferred?

b) Has been there work performed? What is the sign forΔU?Explain



A cylinder A, having Va = 30 litres of an ideal monoatmoicgas, is connected to a second cylinder, B, of circularcross-section, as shown in Fig. 3.16 of the book(shown below).Cylinder B is fitted with a piston of diameter 10 cm, which slideswithout friction or leaking. Initially: Pa = 10 MPa, Ta = 300 K, Vb= 0, and the compression force on the spring is zero. The springobeys Hooke's law and has a stiffness k = 10^5 Nm^-1. Remember thatthe work done by such a spring is: Wspring = -k(Xf^2 - Xo^2)/2,with x = 0 the equilibruim position of the spring.
The valve, V, is opened slowly and the gas leaks through fromA to B, compressing the spring. Equilibrium is eventuallyestablished again at a temperature of 300 K throughout all parts ofthe system.
(a) Calculate the distance by which the spring is compressedin the final equilibrium state.
(b) Determine the work done on the gas.
(c) Calculate the total heat transferred to the gas duringthis process.
Consider now there is an externally applied force holding thepiston hard against the left-hand side of volume B while the valveis opened fully. The external force is then gradually reducedallowing the piston to move slowly while the gas expandsisothermally, compressing the spring.
(d) Calculate the amount by which the spring is ultimatelycompressed.
(e) Establish the work of compression of the spring and thework done by the externally applied force.
(f) Determine the heat transferred to the gas during thisprocess.
WHAT I KNOW:
The back of the book provides all the answers but does notexplain how to get them.
it lists:
(a) .6684 m
(b) -22.34 kJ
(c) 22.34 kJ
(d) .6684 m
(e) 22.34 kJ (on spring), -48.38 kJ (on gas), and 26.04 (extforce)
(f) 48.38 kJ
I understand the answers for b and c given a - since thechange in energy is 0 so W = -Q. and putting in .6684 so Xf and 0for Xo into the Wspring equation you get the 22.34 kJ answer.
I can't however find how to calculate the compression. I haveused PV=NRT and manipulated it to high heaven and just cant getit.
Parts d through f I havn't touched since I havn't been able tofind a
Vapor cycles
5EM - Thermodynamics
September 2010
1 The T-S diagram
The temperature-entropy diagram is an alternative to the well knownpressure-
volume diagram. Before using it to analyze different vapor cycles,we need
to understand it properly.
1. Plot the following transformations for ideal gases in a T-Sdiagram
(a) Isothermal expansion
(b) Isobaric expansion
(c) Isometric heating
(d) Reversible adiabatic expansion
(e) Irreversible adiabatic expansion
2. Repeat the last question, but this time do it for a realsubstance,
starting in the compressed liquid1 region and ending in thesuperheated
region, when possible. Indicate the boundaries of eachregion.
3. We know that under certain circumstances the area under theplot
in a P-V diagram represents the work performed during theprocess.
What does it represent in this case? Under what assumptions isyour
answer true? Compare examples 6.1 and 6.2.
2 Thermal machines
We understand by thermal machine a device capable of transformingther-
mal energy (heat) into mechanical energy (work). We already knowthat
these machines have a limited efficiency which, in the two-sourcesmodel, is
obtained by Carnot’s cycle.
(Compressed liquid is sometimes also called subcooled liquid)
2.1 Carnot cycle
This cycle, although efficient, is impractical. To begin with, theextreme
temperatures of the cycle should be within the sources temperaturesfor a
finite heat flow to exist.
1. Given the temperature of the sources, draw the cycle accordingto the
named limitation.
2. Show that this leads to lower efficiency than the theoreticallimit.
3. Assume that heat flow from/to the sources is proportional to thetem-
perature difference between them and the working fluid, anddemon-
strate that a higher power output is related to a decreasedefficiency.
2.2 Rankine cycle
Out of the several practical possibilities, Rankine cycle and itsvariations is
widely used, especially for electric power generation.
1. Draw the basic cycle in a T-S diagram and explain it.
2. What does the efficiency of the cycle depend on? Comparewith
Carnot’s.
3. What are the differences between the ideal cycle and the realone?
4. Describe how it is modified by superheating and/or reheating.Explain
te benefits.
2.3 Problems
After answering the previous questions solve the followingexercises from the
book: 8.2, 8.4, 8.5, 8.13, 8.19, 8.20
3 Frigorific machines
3.1 Reverse Carnot cycle
We have already studied Carnot cycle in detail as the ideal thermalmachine.
Now we will take is as the starting point to understand thecharacteristics
of frigorific machines.
1. Draw the ideal cycle in a T-S diagram and explain it.
2. Show that this cycle has a theoretical efficiency ß =Tcold/Thot-Tcold
3. What are the difficulties in implementing such cycle in actualdevices?
3.2 Actual refrigerators
1. Why is the turbine replaced by an expansion valve in mostcases?
2. Plot the actual cycle and explain the differences with the idealcase.
3. How do cascade and multistage systems improve the performanceof
the refrigerator?
4. What aspects are important in the choice of a refrigerant fluid?Justify
3.3 Problems
After answering the previous questions solve the followingexercises from the
book: 10.2 10.7, 10.8, 10.9, 10.22, 10.23 10.1D

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