Examples of gas in the following topics:
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- The Ideal Gas Equation in the form $PV=nRT$ is an excellent tool for understanding the relationship between the pressure, volume, amount, and temperature of an ideal gas in a defined environment that can be controlled for constant volume.
- We know the Ideal Gas Equation in the form $PV=nRT$.
- The term $\frac{m}{V}$ appears on the right-hand side of the above rearranged Ideal Gas Law.
- This derivation of the Ideal Gas Equation allows us to characterize the relationship between the pressure, density, and temperature of the gas sample independent of the volume the gas occupies; it also allows us to determine the density of a gas sample given its pressure and temperature, or determine the molar mass of a gas sample given its density.
- Atmospheric science offers one plausible real-life application of the density form of the ideal gas equation.
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- We can derive a form of the Ideal Gas Equation, PV=nRT, that incorporates the molar mass of the gas (M, $g*mol^{-1}$ ).
- The molar mass of an ideal gas can be determined using yet another derivation of the Ideal Gas Law: $PV=nRT$.
- We can plug this into the Ideal Gas Equation:
- This derivation of the Ideal Gas Equation is useful in determining the molar mass of an unknown gas.
- What is the molar mass of the gas?
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- Real gases deviate from the ideal gas law due to the finite volume occupied by individual gas particles.
- The ideal gas law is commonly used to model the behavior of gas-phase reactions.
- At high pressures where the volume occupied by gas molecules does not approach zero
- The particles of a real gas do, in fact, occupy a finite, measurable volume.
- The available volume is now represented as $V - nb$, where b is a constant that is specific to each gas.
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- Take the general gas-phase reaction:
- Recall that the ideal gas law is given by:
- In this expression, $\Delta n$ is a measure of the change in number of moles of gas in the reaction.
- For instance, if a reaction produces three moles of gas, and consumes two moles of gas, then $\Delta n=(3-2)=1$.
- Write the equilibrium expression, KP, in terms of the partial pressures of a gas-phase reaction
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- The Ideal Gas Law does not account for these interactions.
- When the weight of individual gas molecules becomes significant, London dispersion forces, or instantaneous dipole forces, tend to increase, because as molecular weight increases, the number of electrons within each gas molecule tends to increase as well.
- To correct for intermolecular forces between gas particles, J.D. van der Waals introduced a new term into the Ideal Gas Equation in 1873.
- In the term above, a is a constant specific to each gas and V is the volume. van der Waals also corrected the volume term by subtracting out the excluded volume of the gas.
- where b is the excluded volume of the gas, R is the universal gas constant, and T is the absolute temperature.
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- How many moles of gas are contained in the box?
- For the ideal gas equation, note that the product PV is directly proportional to T.
- Add purple gas molecules and watch what happens to the piston.
- Now add yellow gas molecules.
- Try heating or cooling the gas molecules.
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- The van der Waals equation modifies the Ideal Gas Law to correct for the excluded volume of gas particles and intermolecular attractions.
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volume occupied by the gas particles is no longer negligible compared to the
volume of the container and the volume of the gas particles needs to be taken
into account.
- The constants a and b have positive values and are specific to each gas.
- The b term represents the excluded volume of the gas or the volume occupied by the gas particles.
- Distinguish the van der Waals equation from the Ideal Gas Law.
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- Solubility of a gas in water tends to decrease with increasing temperature, and solubility of a gas in an organic solvent tends to increase with increasing temperature.
- In general, solubility of a gas in water will decrease with increasing temperature: colder water will be able to have more gas dissolved in it.
- The trend that gas solubility decreases with increasing temperature does not hold in all cases.
- There are several molecular reasons for the change in solubility of gases with increasing temperature, which is why there is no one trend independent of gas and solvent for whether gases will become more or less soluble with increasing temperature.
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- A 2.0 L container is pressurized with 0.25 atm of oxygen gas and 0.60 atm of nitrogen gas.
- What is the mole fraction of neon gas?
- From the Ideal Gas Law, we can easily calculate the measured pressure of the nitrogen gas to be 0.763 atm.
- The measured pressure of the oxygen gas is 0.215 atm.
- We now define the partial pressure of each gas in the mixture to be the pressure of each gas as if it were the only gas present.
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- Kinetic Molecular Theory explains the macroscopic properties of gases and can be used to understand and explain the gas laws.
- The volume occupied by the individual particles of a gas is negligible compared to the volume of the gas itself.
- The particles of an ideal gas exert no attractive forces on each other or on their surroundings.
- Gas particles are in a constant state of random motion and move in straight lines until they collide with another body.
- Increasing the kinetic energy of the particles will increase the pressure of the gas.