C15 - Ideal Gases Flashcards
How are pressure and volume related? (Boyle’s gas law)?
Pressure of an ideal gas is inversely proportional to volume, given temperature and mass remain constant.
How are pressure and temperature related? (Ideal gas law)
Pressure is proportional to temperature, given volume and mass remain the same.
How are volume and temperature related? (Ideal gas law)
Volume is proportional to temperature, given mass and pressure remain the same.
What is r.m.s. speed?
Root mean squared speed of gas particles (as normal speed would be 0m/s
What assumptions are made in the kinetic model for an ideal gas?
1) The gas contains a very large number of atoms/molecules which move randomly at high speeds.
2) The atoms occupy a negligible volume on comparison to the volume of the gas.
3) Collisions of atoms/molecules are elastic.
4) The time of collisions between atoms/molecules is negligible compared to the time between collisions.
5) Electrostatic forces are negligible except during collisions.
What’s the kinetic theory of matter?
A model to describe the behaviour of atoms or molecules in an ideal gas.
How can the relationship between pressure and temperature tested?
Gather a beaker and water, ice, thermometer, round bottom flask and pressure sensor.
Fill the beaker with hot water. Place the flask in the water and attach it to the pressure sensor.
When the reading on the pressure sensor stops changing, it can be assumed than the water (T1) and the air within the flask (T2) and in thermal equilibrium.
Record the temperature and pressure before adding ice / cold water to the beaker to change the temperature and repeat.
As T increases, particles gain KE, increasing momentum and with shorter time between collisions. This increases the force against the flask walls, increasing pressure.
How can the relationship between volume and temperature tested?
Gather a beaker and water, ice and a capillary tube with a H2SO4 bead (within).
Measure the distance between the end of the tube and the bead.
Fill the beaker with hot water, place the capillary tube within and measure the change in position of the bead. Then add some cold water, wait for the bead to move again then measure the distance and repeat.
As temperature increases, molecules gain KE and move faster, increasing momentum and colliding more frequently. This causes the gas to expand, increasing the volume and forcing the bead to move upwards.
How can the relationship between pressure and volume tested?
Gather a syringe and data logger.
Fill the syringe 3/4 with air and attach to the data logger.
Push the syringe (decreasing volume) to identify the effect on pressure.
Record the values for volume and pressure.
As volume decreases, particles have a smaller space to travel, decreasing the time between collisions. This results in an increase in the force exerted in the syringe walls, increasing pressure.
What’s Boyle’s law?
pV = constant
p is inversely proportional to V
What’s Charles’ law?
V/T = constant
V is proportional to T
What is Gay-Lussac’s law?
p/T = constant
p is proportional to T
