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Audio 0:05:07.953778
The rate of effusion of A is four proportional to the square root of the masses so it has to be sixteen times

Audio 0:12:05.014774
In reactions involving reactant or products, the quantity of a gas is often specified in terms of its volume at a given temperature and pressure. – As noted earlier, stoichiometry involves relationships between amounts in moles. – For stoichiometric calculations involving gases, we can use the ideal gas law to determine the amounts in moles from the volumes, or to determine the volumes from the amounts in moles.
- n = (PV)/(RT)
- V = (nRT)/P

Carbon monoxide reacts with hydrogen to give methanol (CH3OH(g)). What volume (in liters) of H2 gas @ T=82 oC and P=738 Torr do we need to make 35.7 g methanol?

Audio 0:13:33.554013
How many grams of water form when 1.24 L of H2 gas at STP reacts completely with O2?

Real gases often do not behave like ideal gases at high pressure or low temperature.
Ideal gas laws assume
- 1. no attractions between gas molecules; and
- 1. that gas molecules do not take up space.
    - Based on the kinetic molecular theory
At low temperatures and high pressures, these assumptions are not valid.

Audio 0:19:58.672978
Because real molecules take up space, the molar volume of a real gas is larger than predicted by the ideal gas law at high pressures.

Audio 0:21:34.753481
At low pressures, the molar volume of argon is nearly identical to that of an ideal gas.
But as the pressure increases, the molar volume of argon becomes greater than that of an ideal gas. – At the higher pressures, the argon atoms themselves occupy a significant portion of the gas volume, making the actual volume greater than that predicted by the ideal gas law.

Audio 0:22:23.986334
In 1873, Johannes van der Waals (1837–1923) modified the ideal gas equation to fit the behavior of real gases at high pressure.
The molecular volume makes the real volume larger than the ideal gas law would predict.
Van der Waals modified the ideal gas equation to account for the molecular volume. – b is a constant van der Waals determined and is different for every gas because the molecules of each gas are of different sizes.

Audio 0:23:43.041877
Van der Waals modified the ideal gas equation to account for the intermolecular attractions. – a is another constant that van der Waals determined and is different for every gas because the molecules of each gas have different strengths of attraction.

At high temperature, the pressure of gases is nearly identical to that of an ideal gas.
But at lower temperatures, the pressure of gases is less than that of an ideal gas. – At the lower temperatures, the gas atoms spend more time interacting with each other and less time colliding with the walls, making the actual pressure less than that predicted by the ideal gas law.

Audio 0:25:16.451107
Combining the equations to account for molecular volume and intermolecular attractions, the following equation for real gases is derived:

A plot of PV/RT versus P for 1 mole of a gas shows the difference between real and ideal gases.

Audio 0:27:22.870965
A plot of PV/RT versus P for 1 mole of a gas shows the difference between real and ideal gases.
It reveals a curve that shows that the PV/RT ratio for a real gas is generally lower than ideal for “low” pressures—meaning that the most important factor is the intermolecular attractions.
It reveals a curve that shows that the PV/RT ratio for a real gas is generally higher than ideal for “high” pressures—meaning that the most important factor is the molecular volume.

Term	Definition
molecular volume	makes the real volume larger than the ideal gas law would predict to be more realistic
b	constant van der Waals determined and is different for every gas because the molecules of each gas are of different sizes
a	constant that van der Waals determined and is different for every gas because the molecules of each gas have different strengths of attraction