Basic Chemistry Chapter 11 Gases Chapter 11 Lecture Fourth Edition Chapter 11 Gases 11.6 Combined Gas Law Learning Goal Use the combined gas law to find the final pressure, volume, or temperature of a gas when changes in two of these properties are given and the amount of gas is constant.

Combined Gas Law Combined gas law incorporates all pressure-volume-temperature relationships for gases previously studied is useful for studying the effect of changes in two of these variables on the third variable, while the amount remains constant

Summary of Gas Laws

Learning Check Helium gas has a volume of 0.180 L, a pressure of 0.800 atm, and a temperature of 29 °C. At what temperature (°C) will the gas have a volume of 90.0 mL and a pressure of 3.20 atm?

Step 1 Organize the data in a table of initial and final conditions. Solution Helium gas has a volume of 0.180 L, a pressure of 0.800 atm, and a temperature of 29 °C. At what temperature (°C) will the gas have a volume of 90.0 mL and a pressure of 3.20 atm? Step 1 Organize the data in a table of initial and final conditions. Conditions 1 Conditions 2 P1 = 0.800 atm P2 = 3.20 atm V1 = 0.180 L (180. mL) V2 = 90. mL T1 = 29 °C + 273 = 302 K T2 = ?

Solution Helium gas has a volume of 0.180 L, a pressure of 0.800 atm, and a temperature of 29 °C. At what temperature (°C) will the gas have a volume of 90.0 mL and a pressure of 3.20 atm? Step 2 Rearrange the gas law equation to solve for the unknown quantity.

Solution Helium gas has a volume of 0.180 L, a pressure of 0.800 atm, and a temperature of 29 °C. At what temperature (°C) will the gas have a volume of 90.0 mL and a pressure of 3.20 atm? Step 3 Substitute values into gas law equation and calculate.

Learning Check A gas has a volume of 675 mL at 35 °C and 0.850 atm pressure. What is the volume (mL) of the gas at −95 °C and a pressure of 802 mmHg?

Step 1 Organize the data in a table of initial and final conditions. Solution A gas has a volume of 675 mL at 35 °C and 0.850 atm pressure. What is the volume (mL) of the gas at −95 °C and a pressure of 802 mmHg? Step 1 Organize the data in a table of initial and final conditions. Conditions 1 Conditions 2 P1 = 0.850 atm P2 = 802 mmHg = 1.06 atm V1 = 0.675 mL V2 = ? T1 = 35 °C + 273 = 308 K T2 = −95 °C + 273 = 178 K

Solution A gas has a volume of 675 mL at 35 °C and 0.850 atm pressure. What is the volume (mL) of the gas at −95 °C and a pressure of 802 mmHg? Step 2 Rearrange the gas law equation to solve for the unknown quantity.

Solution A gas has a volume of 675 mL at 35 °C and 0.850 atm pressure. What is the volume (mL) of the gas at −95 °C and a pressure of 802 mmHg? Step 3 Substitute values into gas law equation and calculate.