Chemistry a Study of Matter Answer Key

University:
High School
Course:
High School Chemistry
Academic year:

2020
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419

Pages:

4
Author:

Duappyarcawayr1

The Volume of a fixed mass of gas varies indirectly with the pressure at constant temperature P₁V₁ = P₂V₂ Kinetic Theory and Boyle's Law Pressure of a gas is caused by the molecules of the gas striking the walls of the container If the gas is compressed to half the volume it had, twice as many molecules are present in any given volume Twice as many impacts per second on the walls * pressure of the gas will double Ex 1: A balloon filled with Helium has a volume of 457 mL at standard atmospheric pressure. After the balloon is released, it reaches an altitude of 6.3 km where the pressure is only 65.5 kPa. What is the volume of the balloon at this altitude? P₁V₁ = P₂V₂ 101.3 kPa x 457 mL = 65.5 kPa x V₂ V₂ = 706.8 mL Ex 2: Under a pressure of 673 mm Hg, a confined gas has a volume of 335 mL. If the pressure is increased until the volume is 252 mL, what is the new pressure, assuming the temperature remains constant? P₁V₁ = P₂V₂ 673 mm Hg x 335 mL = P₂ x 252 mL P₂ = 898 mm Hg Charles's Law For a FIXED MASS of gas, as long as the PRESSURE is held constant, the VOLUME varies directly with the KELVIN TEMP V₁/T₁ = V₂/T₂ The Kelvin Temperature Scale ABSOLUTE zero Lowest possible TEMP NEVER been reached 0K = ABSOLUTE zero K = °C + 273 Ex 1: A quantity of gas occupies a volume of 506 cm³ at a temperature of 147°C. Assuming the pressure stays constant, at what temperature will the volume of the gas be 604 cm³? 506 cm³ / T₁ = 604 cm³ / T₂ T₂ = 470 K Kinetic Molecular Theory and Charles's Law Doubling the KELVIN TEMP of a gas DOUBLES the average KINETIC ENERGY of its molecules Faster moving molecules strike the walls of the CONTAINER more OFTEN From BOYLE'S Law we derive that the VOLUME would have to DOUBLE if the KELVIN TEMP is Doubled so that PRESSURE would remain CONSTANT Boyle's Law: When TEMP is held constant, the pressure and volume of a gas are indirectly proportional. Mathematically, Boyle's law is stated P₁V₁ = k (constant) or P₁V₁ = P₂V₂ At a pressure of 405 kPa, the volume of a gas is 6.00 cm³. Assuming the temperature remains constant, at what pressure will the new volume be 4.00 cm³? 405 kPa x 6.00 cm³ = P₂ x 4.00 cm³ P₂ = 607.5 kPa A volume of gas at 1.10 atm was measured at 326 cm³. What will be the volume if the pressure is adjusted to 1.90 atm? 1.10 atm x 326 cm³ = 1.90 atm x V₂ V₂ = 188.7 cm³ If 36.5 m³ of a gas are collected at a pressure of 755 mm Hg, what volume will the gas occupy if the pressure is changed to 632 mm Hg? 755 mm Hg x 36.5 m³ = 632 mm Hg x V₂ V₂ = 43.6 m³