Charles' Law

QuickNotes

Charles's Law: V1/T1= V2/T2

  • T refers to temperature measured in Kelvin (K) 
    • Temperature in Kelvin = C + 273
  • V refers to volume measured in Liters (L)
  • Just like in Boyle's law, the temperatures and volumes must be given in the same units on both sides of the equation. For example:
(8 L)/(40 K) = (4 L)/(20 K)
(8 mL)/(40K) = (4 L)/(20 C) 

  • Questions using Charles's law are not affected by pressure. To recognize that you need this formula, notice that various data about temperature and volume will be given followed by a statement or implication that pressure is constant. 
  • Important Concept: Volume and Temperature are directly proportional. This means that as temperature increases, volume increases, and vice versa.
Examples:

Example 1: Calculate the decrease in temperature when 2.00 L at 20.0 °C is compressed to 1.00 L.

1. Convert the temperature into Kelvin:
20+273 = 293 K

2. (2.00 L)/(293 K) = (1.00 L)/(x K), where
x  = 146.5 K = 147 K

The temperature decreases by 147 K.
 
Example 2: 600.0 mL of air is at 20.0 °C. What is the volume at 60.0 °C?
1. Convert all temperatures to Kelvin:
20°C + 273 = 293 K
60°C + 273 = 333 K

2. (600.0)/(293) = (x)/(333), where
x = 681.9 mL = 682 mL

Check out this review video on Charles's Law!


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