Charles

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Charles Law

• volume temperature

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Temperature Changes Matter

• solids liquids expand/contract as temperature
  changes
• usually very small change
• gases show large volume changes as temperature
  changes

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ice water bath hot water
bath balloons can expand contract with ? temp
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Jacques Charles
Balloonist 1780s experiments that showed how
volume of gases depends on temperature
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How do hot air balloons work?
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Relationship between V and T
pressure moles are held constant high temp
gas particles move faster collide with walls
more often
pressure is constant, so volume will increase
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Volume-Temperature Data
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What did Charles do next?

• graphed his data

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volume vs temperature of gas
volume (ml)
temp (ºC)
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Linear Relationship

• plot Volume vs C forms straight line
• relationship between V and T is linear

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• Charles extrapolated graph to 0 volume
• and found X-intercept is -273 C

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Hints of Kelvin scale

• Charles extrapolated data to see T at which
  volume was 0ml WHY?
• first indication
• that -273 C
• had fundamental
• meaning

-273 C
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(No Transcript)
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Plot Volume vs. T (K)

• get straight line passing through 0 point
• relationship between V T is direct

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Charles Law verbally

• volume of gas at constant pressure moles
  varies directly with its absolute temperature

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Charles Law mathematicallyV kT

• V1 V2

Given any 3 variables, can find 4th
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Charles Law graphically

• plot V vs Kelvin T
• straight line passing through 0

V vs T of a gas
V
(K)
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Problem 1

• 150 mL of a gas at constant pressure
• temperature increases from 20C to 40C
• what is the new volume?

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Step 1 convert T1 and T2 to Kelvin
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Step 2 Rearrange equation

• V1 V2 becomes V1T2 V2
• T1 T2 T1

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Step 3 Solve

• V1T2 V2
• T1
• (150 mL)(313 K) 160 mL
• 293 K