CHEM104 Lecture Notes - Lecture 3: Kinetic Theory Of Gases, Stoichiometry, Effusion

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adrianaud

15 Feb 2017

School

University of Delaware

Department

Chemistry and Biochemistry

Course

CHEM104

Professor

Mike Dao

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Document Summary

Chapter 5 part 2: volume directly proportional to the number of gas molecules. More had molecules= larger volume: count number of gas molecules by moles, equal volumes of gases contain equal numbers of molecules. Ideal gas law: absolute pressure is directly proportional to kelvin temperature and the number of moles of the gas and is inversely proportional to the volume of the gas/ Standard conditions (stp: standard pressure = 1 atm, standard temperature 273 k or 0 c. Molar volume: at stp: 1 mol of gas= 22. 4l. Density of standard conditions: density of a das is generally given at g/l. Mixture of gases: considered one gas. Partial pressures: pressure of a single gas in the mixture. Total pressure and fractions of the mixture are known. Volume, temperature, and number of moles of each gas are know. Sun of all partial pressures of all of the gases equals total pressure (dalton"s law of partial pressure.

Related Questions

1. The number of molecules in 1atm of gas at constant pressure and temperature is identical,regardless of the identity of the molecules in the gas. Which ofthe following other statements are also true?

A) The molecules in a gas slow down with increasingtemperature.
B) The total number of atoms in the gas at standard temperature andpressure can vary depending on the identity of the gas
C) The volume of a gas is independent of the pressure of thegas.
D) The temperature of a gas is independent of the pressure of thegas.

2. In an ideal gas, P*V = n*R*T where P = pressure, V=volume,n=number of moles, R=gas constant, and T=temperature. Consider agas with pressure = 1 atm, 1 mole of molecules, and a temperatureof 295 K. R=0.082 atm*L/(mol * K). How much volume should this gasoccupy? Choose the closest answer.

A) 1.0 L
B) 30.6 L
C) Infinite space
D) 22.4 L

3. Suppose you conducted an experiment using Helium gas. Giventhat Helium is much lighter than Propane and Butane, you wouldexpect the relationship between the volume of helium and thepressure to be:

A) exponential, because Helium is lighter
B) inversely proportional, just like propane and butane
C) directly proportional, just like propane and butane
D) periodic, because Helium is lighter

4. What do you predict would happen if you conducted anexperiment using sulfur hexafluoride (SF6) which is much heavierthan methane or butane?

A) The volume of SF6 would be larger and this would affect thepressure in the flask
B) The relationship between temperature and volume would beinversely proportional for a gas of higher molecular weight
C) The speed of the SF6 gas molecules would be faster causing adifference in the temperature measurements
D) The relationship between temperature and volume would bedirectly proportional just as it was for methane and butane

1. The number of molecules in 1 atm of gas at constant pressureand temperature is identical, regardless of the identity of themolecules in the gas. Which of the following other statements arealso true?

A) 1.0 L
B) 30.6 L
C) Infinite space
D) 22.4 L

3. Suppose you conducted an experiment using Helium gas. Giventhat Helium is much lighter than Propane and Butane, you wouldexpect the relationship between the volume of helium and thepressure to be:

A) exponential, because Helium is lighter
B) inversely proportional, just like propane and butane
C) directly proportional, just like propane and butane
D) periodic, because Helium is lighter

4. What do you predict would happen if you conducted anexperiment using sulfur hexafluoride (SF6) which is much heavierthan methane or butane?

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

CHEM104 Lecture Notes - Lecture 3: Kinetic Theory Of Gases, Stoichiometry, Effusion

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