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Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,Charless Law,The relationship between temperature and volume,If we place a balloon in liquid nitrogen it shrinks:,How Volume Varies With Temperature,So, gases shrink if cooled.,Conversely, if we heat a gas it expands (as in a hot air balloon).,Lets take a closer look at temperature before we try to find the exact relationship of V vs. T.,No. 68,F (20,C) is not double 50,F,(10,C),Yes. 44 lb (20 kg) is double 22 lb (10 kg),Whats the difference?,Weights (kg or lb) have a minimum value of 0.,But the smallest temperature is not 0,C.,We saw that doubling P yields half the V.,Yet, to investigate the effect of doubling temp-erature, we first have to know what that means.,An experiment with a fixed volume of gas in a cylinder will reveal the relationship of V vs. T,Temperature scales,Is 20,C twice as hot as 10,C?,Is 20 kg twice as heavy as 10 kg?,Temperature vs. Volume Graph,(fig.7,8 pg.430),5,10,15,20,25,30,Volume (mL),Temperature (,C),0,100, 273,25 mL at 22C,31.6 mL, 23.1 mL,Y=0.0847x + 23.137,If a volume vs. temperature graph is plotted for gases, most lines can be interpolated so that when volume is 0 the temperature is -273,C.,Naturally, gases dont really reach a 0 volume, but the spaces between molecules approach 0.,At this point all molecular movement stops.,273,C is known as “absolute zero” (no E,K,),Lord Kelvin suggested that a reasonable temp-erature scale should start at a true zero value.,He kept the convenient units of,C, but started at absolute zero. Thus, K =,C + 273.,62,C =,?,K: K=,C+273 = 62 + 273 = 335 K,Notice that kelvin is represented as K not,K.,The Kelvin Temperature Scale,What is the approximate temperature for absolute zero in degrees Celsius and kelvin?,Calculate the missing temperatures,0,C = _ K100,C = _ K,100 K = _,C ,30,C= _ K,300 K = _,C 403 K = _,C,25,C = _ K0 K = _,C,Kelvin Practice,273,373,173,243,27,130,298,273,Absolute zero is ,273,C or 0 K,Looking back at the temperature vs. volume graph, notice that there is a direct relationship.,It can be shown that V/T = constant,Read pages 432-3. Answer these questions:,Give Charless law in words & as an equation.,Charless Law,: as the temperature of a gas increases, the volume increases proportionally, provided that the pressure and amount of gas remain constant,V,1,/T,1,= V,2,/T,2,Charless Law,A sample of gas occupies 3.5 L at 300 K. What volume will it occupy at 200 K?,If a 1 L balloon is heated from 22C to 100C, what will its new volume be?,Do questions 16, 17, 19 on page 434,V,1,= 3.5 L, T,1,= 300K, V,2,= ?, T,2,= 200K,Using Charles law: V,1,/T,1,= V,2,/T,2,3.5 L / 300 K = V,2,/ 200 K,V,2,= (3.5 L/300 K) x (200 K) =,2.3 L,V,1,= 1 L, T,1,= 22C = 295 K,V,2,= ?, T,2,= 100 C = 373 K,V,1,/T,1,= V,2,/T,2,1 L / 295 K = V,2,/ 373 K,V,2,= (1 L/295 K) x (373 K) =,1,.26 L,
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