CHMA10H3 Lecture 10: Non-ideal Gases & Quantum Model of Atom

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29 Jan 2019

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The escape of molecules through a tiny orifice. Rate is proportional to molecular mass: graham"s law. Applicable to molecular speeds, travel times/distance etc . Lower molecular weight = higher rate of effusion. Real gases deviate from the gas laws in very specific conditions (e. g. specified temperature and pressure) Kinetic molecular theory of ideal gases assumes: Volume of gas particles is negligible (but not zero!) Gas molecules have some sort of stickiness . At high pressure and low temperature, the ideal gas fails. Volume of real gas is larger than predicted gas law. Pressure of a real gas is smaller than predicted by the ideal gas law since attractive forces between particles reduce pressure. The gases aren"t just bouncing off each other, they stick" to each other a little bit. At low temperature, loss of kinetic energy in collisions between molecules and formation of clusters of molecules.

Related Questions

M 121 1 201 Ideal Gas Law (PV n Experiment to T ) Determine the Ideal Gas Constant R 1. Conduct basic measurements, measurement , mathematical calculations and conversions for of volume, pressure, and temperature: calculate percent error and account for sources of error in an e xperimental result name and by following safety proced ty experiments for a redox reaction by using equipment identifiable by form chemical calculations using mass, mole and volumes and idenify limitatios of measuring devices in order to state the uncertainty/significant figures in measurements and calculation results. 5. Demonstrate a proficiency in relating the chemistry of gases to everyday phenomenon. Introduction Molecules in gases have very little attraction for one another, because relative to their size, they are so far apart from each other. For this reason we can often assume that a gas behaves "idcally." meaning that the physical behavior of the gas is independent of the composition of the gas. If a gas behaves ideally, then its physical properties can be described by the Ideal Gas Equation: Let's consider why the variables in the ideal gas equation have the relationships expressed in Equation 1aã The ideal gas equation assumes that there are no attractive forces between gas molecules. One can picture two billiard balls bouncing off one another in a totally clastic collision. If these molecules are placed in a balloon the collisions will occur not only with each other but also with the wall of the balloon, causing the balloon to expand. This expansion can be measured as a volume (V). More molecules will cause more collisions and thus more expansion. Therefore the quantity of molecules or number of moles (n) is directly proportional to the volume, and thus volume and number of moles appear on opposite sides of the equation. Another factor to consider is the kinetic energy of these molecules. Kinetic energy is related to the temperature (T) of the molecules, in that the kinetic energy. If the collisions with the wall of the balloon are happening at a very high speed due to high kinetic energy, the collisions will be harder and more frequent and thus the wall of the balloon will be pushed out further (a larger volume) than if the kinetic energy were less. The result is that volume is also directly proportional to the temperature. This relationship is seen in Equation la with (T) on the right side of the equation and (V) on the left. higher the temperature the greater the considered. While the molecules inside the balloon are pushing the balloon out, there are also molecules in thea Finally the pressure of the outside environment (atmospheric pressure) needs to be 59

Question 11 pts

Which general statement about gases is NOT correct?

The molecules of a pure gas are distributed evenly throughout the container.

Gases are much less dense than liquids or solids

Molecules in a gas mixture can form layers according to their densities

Gases can be compressed, even to the point of liquefaction

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Question 21 pts

Which example is the greatest pressure?

1.00 atm

101 kPa

760 mm Hg (= 760 torr)

All of the above pressures are equal.

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Question 31 pts

Which example is the greatest pressure?

850 mm Hg (= 850 torr)

1.5 atm

All of the above pressures are equal.

96 kPa

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Question 41 pts

Assuming all other variables are held constant, a graph of which of the following will NOT yield a straight line?

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Question 51 pts

A sealed vessel contains 0.250 mol of oxygen gas. Which of the following will result in a decrease in the pressure of the oxygen gas?

increasing the number of moles of oxygen

increasing the temperature of the vessel

increasing the volume of the vessel

adding some helium to the vessel

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Question 61 pts

According to Charlesâs law, which change will cause the pressure of a gas to double? Pressure and amount of gas are constant.

The temperature decreases from 650 K to 325 K.

The temperature of the sample decreases fromï¿½88 Â°C to 44 Â°C.

The temperature of the sample increases fromï¿½22 Â°C to 44 Â°C.

The temperature of the sample increases fromï¿½250 K to 500 K.

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Question 71 pts

Which set of units for P, V, and T can be used for combined gas law calculations?

torr, L, and Kelvins

tm, g/L, and Kelvins

atm, mL, and degrees Celsius

inches of mercury, g/mL, and degrees Celsius

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Question 81 pts

The vapor pressure of a gas is

the atmospheric pressure at which the boiling point is determined.

the pressure at a Kelvin temperature exactly two times the boiling point.

impossible to determine experimentally without knowing the temperature and volume.

the pressure above a gas sample when evaporation and condensation are balanced.

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Question 91 pts

In a chemistry experiment where CO2 is collected over water, the atmospheric pressure is 755 mm. The partial pressure of water at the temperature in the lab is 24.2 mm. What is the pressure of the CO2?

779 mm

731 mm

More information is needed to answer this question

755 mm

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Question 101 pts

Which statement is NOT true according to the kinetic molecular theory of gases?

Molecules undergo elastic collisions

Molecules move in straight-line paths.

Molecules of different gases have differentï¿½kinetic energies at the same temperature

Molecules occupy a negligible volume.

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