Gas Laws

Gas Laws Review (participation)

Take home quiz after class

Multiple Choice

PV=nRT

If volume goes down, pressure goes _____.

• up

• down

Multiple Choice

PV=nRT

If temperature goes up, pressure goes _____.

• up

• down

PV=nRT

• Opposite sides: directly proportional (if T $\uparrow$ , P $\uparrow$  )
  

• Same side: inversely proportional (if P $\uparrow$ , V $\downarrow$ )
  

Multiple Choice

PV = nRT

If the temperature goes up, volume must go ____.

• up

• down

Multiple Choice

PV=nRT

If the number of moles (n) goes up, temperature must go ____.

• up

• down

PV=nRT

*These relationships assume everything else stays constant

• when comparing P vs V, everything else (n, R, T) is constant

• when comparing T vs V, everything else (P, n, R) is constant

PV=nRT

If n, R, T stay constant, then:

•  $P_1V_1=nRT=P_2V_2$  
  

• Boyle's Law - allows us to solve for changes in pressure and volume

• P and V can be in any units as long as same on both sides

PV=nRT

If n, R, P stay constant, then:

•  $\frac{V_1}{T_1}=\frac{nR}{P}=\frac{V_2}{T_2}$ 

• Charles' Law - allows us to solve for changes in volume and temperature

• V can be in any units as long as same on both sides, T must be in Kelvin

Combined Gas Law

•  $\frac{P_1V_1}{T_1}=nR=\frac{P_2V_2}{T_2}$  

• All three (P, V, T) are changing together

• T must be in Kelvin, everything just same on both sides

Multiple Choice

$$P_1V_1=P_2V_2$$  

If a balloon occupies 5L at a pressure of 10atm, what volume will the balloon be at 20atm?

• 2.5L

• 5L

• 10L

Multiple Choice

$$P_1V_1=P_2V_2$$  

If an inflatable ring has a volume of 4L at 1atm, what pressure is needed to increase the volume to 6L?

• 0.67 atm

• 1.5 atm

• 2 atm

Multiple Choice

$$\frac{V_1}{T_1}=\frac{V_2}{T_2}$$  

A balloon takes up 8L at a temperature of 300K. What will be the volume if the temperature is increased to 450K?

• 8L

• 12L

• 16L

Multiple Choice

$$\frac{V_1}{T_1}=\frac{V_2}{T_2}$$  

A floaty ring has a volume of 5L at an unknown temperature. If the temperature is increased to 300K, the volume becomes 15L. What was the initial temperature? 

• 100K

• 150K

• 300K