Pressure – Temperature: Gay-Lussac and Dalton

OUTCOME QUESTION(S): C11-2-07 UNITS AND RELATIONSHIPS Describe the various units used to measure pressure and convert between units. Include: atmospheres, kilopascals, millimetres of mercury Experiment to develop the relationship between the pressure and volume of a gas using visual, numeric, and graphical representations. Include: Boyle’s Law Experiment to develop the relationship between the volume and temperature of a gas using visual, numeric, and graphical representations. Include: Charles’ Law, Absolute zero, Kelvin scale, Ideal gas Develop the relationship between the pressure and temperature of a gas using visual, numeric, and graphical representations. Include: Gay-Lussac’s Law, Dalton’s Law Vocabulary & Concepts  Partial pressure

pressure and temperature show a constant direct relationship Joseph Louis Gay-Lussac: (1778 - 1850) Experimented with pressure and temperature of a sample at constant volume. Data plotted – as pressure vs. temperature Linear relationship emerges (a straight line) Slope is constant and predictable rise = constant run P = constant T pressure and temperature show a constant direct relationship rise run

(when held at a constant volume) Gay-Lussac’s Law: The pressure of a given amount of gas varies directly with the temperature in Kelvin. (when held at a constant volume) P α T

What is the new pressure of 200 kPa of gas if the temperature in Kelvin is doubled? P α T A direct relationship suggests: 400 kPa 2 α 2 Double the temperature will double the original pressure If temperature is reduced to 1/3rd ? 1 3 α 1 3 66.7 kPa Decreased temperature will reduce pressure to 1/3 the original Direct of a third is a third

= P1 T1 P2 T2 P1 T1 P2 T2 G-L’s Law Equation: P = constant T rise run **All temperatures must be in Kelvin. P = constant T P1 T1 P2 T2 Initial conditions always equal Final conditions when divided

If a 12. 0 L sample of gas has a pressure of 101. 3 kPa at 0 If a 12.0 L sample of gas has a pressure of 101.3 kPa at 0.0°C, calculate the new pressure at 128°C. P1 = 101.3 kPa T1 = 0oC + 273 = 273 K P2 = ? T2 = 128oC + 273 = 401 K P1 P2 = T1 T2 Predicted result? 101.3 149 kPa = P2 (401) 273 Increasing the temperature by 128 degrees will cause an increase in pressure to 149 kPa

(when held at a constant temperature) Dalton’s Law of Partial Pressure: The total pressure is the sum of the partial pressures exerted by each gas in a container. (when held at a constant temperature) Ptotal = P1 + P2 + P3 + P4 … The partial pressure of a gas in a mixture is the same as the pressure of the gas in the container by itself

Ptotal = P1 + P2 + P3 + P4 … PT = 50.5 + 20.0 + 30.5 PT = 101 kPa The following gases are found in a 10.0 litre container and held at 250 K, what is the total pressure inside the container? O2 gas with a partial pressure of 50.5 kPa He gas with a partial pressure of 20.0 kPa Ar gas with a partial pressure of 30.5 kPa Ptotal = P1 + P2 + P3 + P4 … PT = 50.5 + 20.0 + 30.5 PT = 101 kPa

PT = PO2 + PHe + PX PX = 25 - 15 - 7 PX = 3 atm A mixture of three gases in a 30.0 litre container, held at 270 K have a total pressure of 25 atm. What is the partial pressure of the unknown gas? O2 - partial pressure = 15 atm He - partial pressure = 7 atm X - partial pressure = ? PT = PO2 + PHe + PX PX = 25 - 15 - 7 PX = 3 atm

Two individual gases held in containers are joined into a new 10 Two individual gases held in containers are joined into a new 10.0 litre container. What is the total pressure inside the new container? 2.0 L of O2 at an original pressure of 202.6 kPa 3.00 L of Ne at an original pressure of 303.9 kPa Hint: what does a new larger container do to the partial pressure exerted by each gas? PT = P1 + P2

P1V1 = P2V2 Oxygen: (202.6)(2.00) = P2 (10.0) P2 = 40.5 kPa Neon: (303.9)(3.00) = P2 (10.0) P2 = 91.2 kPa Need to use the correct Law to find the partial pressure for each gas in the new container PT = 40.5 + 91.2 PT = 131.7 kPa

CAN YOU / HAVE YOU? C11-2-07 UNITS AND RELATIONSHIPS Describe the various units used to measure pressure and convert between units. Include: atmospheres, kilopascals, millimetres of mercury Experiment to develop the relationship between the pressure and volume of a gas using visual, numeric, and graphical representations. Include: Boyle’s Law Experiment to develop the relationship between the volume and temperature of a gas using visual, numeric, and graphical representations. Include: Charles’ Law, Absolute zero, Kelvin scale, Ideal gas Develop the relationship between the pressure and temperature of a gas using visual, numeric, and graphical representations. Include: Gay-Lussac’s Law, Dalton’s Law Vocabulary & Concepts  Partial pressure