 Heat Energy transferred due to differences in temperature  Temperature Measure of the average kinetic energy of particles composing a material  Pressure Force per unit area  Volume The amount of space a material occupies

 Pressure and volume are indirectly related  Pressure and 1/volume are directly related

1. A balloon initially occupies 12.4 L at 1.00 atm. What will be the volume at atm? 2. A sample of gas expands from 10.0 L to 30.0 L. If the initial pressure was 1140 mm Hg, what is the new pressure?

 Using Boyles law Calculate: A balloon contains 40.0 L of a gas at kPa. What is the volume of the gas when the balloon is brought to an altitude where the pressure is only 10.0 kPa? (Assume that the temperature remains constant.)

 Temperature and volume are directly related  At constant pressure  Absolute zero Theoretically, point at which all motion stops. The temperature at which volume of a gas becomes zero when the plot of temperature vs. volume is extrapolated.

1. Calculate the decrease in temperature when 2.00 L at 20.0°C is compressed to 1.00 L. 2. A gas occupies mL at a temperature of 27.0°C. What is the volume at 132.0°C?

 Temp and pressure are directly related  Absolute zero The temperature at which the pressure of a gas becomes zero when a plot of pressure versus temperature for a gas is extrapolated  -273  C = 0 K or K =  C + 273

1. Consider a container with a volume of 22.4 L filled with a gas at 1.00 atm at 273 K. What will be the new pressure if the temperature increases to 298K?

2. A container is initially at 47 mm Hg and 77K (liquid nitrogen temperature.) What will the pressure be when the container warms up to room temperature of 25  C?

3. A thermometer reads a pressure of 248 Torr at 0.0  C. What is the temperature when the thermometer reads a pressure of 345 Torr?

 STP (standard temperature and pressure)  T = 273K (which is 0°C)  P = 1 atm, kPa, 760 mmHg, 760 torr  V = 22.4 L (one mole of gas)  Formula P 1 V 1 =P 2 V 2 T 1 T 2

 10.0 cm 3 volume of a gas measured 75.6 kPa and 60.0  C is to be corrected to correspond to the volume it would occupy at STP.

The Kinetic Molecular Theory describes IDEAL gases  Most gases approximate ideal gases and the model works great for most gases.  Some REAL gases need adjustments Real gases experience electrostatic attractions. Real gases have volume

 PV = nRT P = pressure-measured in atm, kPa, mmHg, torr V = volume - usually measured in L T = temperature in K n = number of moles (“mol”) R = “universal gas constant”  Calculate R if pressure is in atm: (most common) (1 atm)(22.4 L) = atm*L/K*mol (273 K)(1mol)

 Calculate R if pressure is in kPa: (most common) (101.3 kPa)(22.4 L) = kPa*L/K*mol (273 K)(1mol)  Calculate R if pressure is in torr or mm Hg: (rarely used) (760 torr)(22.4 L) = torr*L/K*mol (273 K)(1mol) (760 mmHg)(22.4 L) = mmHg*L/K*mol (273 K)(1mol)

 Calculate the temperature of moles of a gas occupying a volume of 20.0 L with a pressure of 99.9 kPa. (99.9 kPa)(20 L) = K (8.312 kPa*L/K*mol)(.5 mol)

 Calculate the moles of a gas occupying a volume of mL with a temperature of 25.5  C and a pressure of 755 torr. (755 torr)(.5 L) = mol (298.5 K)(62.36 torr*L/K*mol)

 Calculate the volume of 1.00 mol of H 2 at STP STP = 0  C 273  K and 1.00 atm  P = 1 atm  V = ?  n = 1 mol  R = L-atm/mol-K  T = 273K PV = nRT nRT/P = V (1 mol)(.0821L-atm/mol-K)(273 K) = 1 atm That number should look familiar! It is the volume of one mole of any gas at STP. The number from the mole map comes from the ideal gas law L

End