Charles’s lawstates that the volume of a given mass of gasis directly proportional to its kelvin temperature at constantpressure. For help with understanding direct relationships, seetheMath Handbook,page 905. So for any two sets of condi-tions, Charles’s law can be expressed asHereV1andT1represent any initial pair of conditions,whileV2andT2are any new set of conditions. As with Boyle’slaw, if you know any three of the four values, you can cal-culate the fourth using the equation. The temperature must be expressed in kelvin units when using the equa-tion for Charles’s law. The kelvin scale starts at absolute zero, which corre-sponds to –273.15°C and is 0 K. Because a Celsius degree and a kelvin unitare the same size, it is easy to convert a temperature in Celsius to kelvin units.Round 273.15 to 273, and add it to the Celsius temperature.TK273TCVT11VT22424Chapter 14Gasesproblem-solvingLABHow is turbochargingin a carengine maximized? Interpreting Scientific IllustrationsAftergasoline and air are burned in the combustionchamber of an automobile, the resulting hotgases are exhausted out the tailpipe. The horse-power of an automobile engine can be signifi-cantly improved if the energy of these exhaustgases is used to operate a compressor that forcesadditional air into the combustion chamber.Outside air is then blown over this compressedair to cool it before it enters the engine.Increasing the power of an engine in this manneris known as turbocharging.AnalysisExamine the illustration of an engine fitted witha turbocharging system. The paths of the exhaustgas, entering combustion air, and the cooling airare shown.Thinking Critically1.What property of the exhaust gas is beingused to turn the turbine that runs the com-pressor? Explain.2.If more power is to be gained from this design,what must also accompany the extra supply ofoxygen to the combustion chamber?3.What property does the compressor alter sothat more air can be injected into the combus-tion chamber? Explain.4.Why does the air in the compressor get hot,and why does cooling help to improve thepower of the engine?Charge-air coolerTurbochargerExhaustgasTurbinewheelCompressorwheelAirinletEngine cylinderOil outletOil inletFigure 14-4This graph illustrates the directlyproportional relationshipbetween the volume and thekelvin temperature of a gas heldat constant pressure. When thekelvin temperature doubles, thevolume doubles.