<< Chapter < Page Chapter >> Page >

Observation 1: limitations of the validity of the ideal gas law

To design a systematic test for the validity of the Ideal Gas Law , we note that the value of P V n R T , calculated from the observed values of P , V , n , and T , should always be equal to 1, exactly. Deviation of P V n R T from 1 indicates a violation of the Ideal Gas Law . We thus measure the pressure for several gases under a variety of conditions by varying n , V , and T , and we calculate the ratio P V n R T for these conditions.

Here , the value of this ratio is plotted for several gases as a function of the "particledensity" of the gas in moles, n V . To make the analysis of this plot more convenient, the particle density is given in termsof the particle density of an ideal gas at room temperature and atmospheric pressure ( i.e. the density of air), which is 0.04087 mol L . In this figure , a particle density of 10 means that the particle density of the gas is 10 times the particle density of air at roomtemperature. The x-axis in the figure is thus unitless.

Validity of the ideal gas law

Note that P V n R T on the y-axis is also unitless and has value exactly 1 for an ideal gas. We observe inthe data in this figure that P V n R T is extremely close to 1 for particle densities which are close to that of normal air. Therefore, deviations fromthe Ideal Gas Law are not expected under "normal" conditions. This is not surprising, since Boyle's Law , Charles' Law , and the Law of Combining Volumes were all observed under normal conditions. This figure also shows that, as the particle density increases above the normalrange, the value of P V n R T starts to vary from 1, and the variation depends on the type of gas we are analyzing. However, even forparticle densities 10 times greater than that of air at atmospheric pressure, the Ideal Gas Law is accurate to a few percent.

Thus, to observe any significant deviations from P V n R T , we need to push the gas conditions to somewhat more extreme values. The results for such extreme conditions areshown here . Note that the densities considered are large numbers corresponding to very high pressures. Under theseconditions, we find substantial deviations from the Ideal Gas Law . In addition, we see that the pressure of the gas (and thus P V n R T ) does depend strongly on which type of gas we are examining.Finally, this figure shows that deviations from the Ideal Gas Law can generate pressures either greater than or less than that predictedby the Ideal Gas Law .

Deviations from the ideal gas law

Observation 2: density and compressibility of gas

For low densities for which the Ideal Gas Law is valid, the pressure of a gas is independent of the nature of the gas, and is therefore independent of the characteristics of theparticles of that gas. We can build on this observation by considering the significance of a low particle density. Even at thehigh particle densities considered in this figure , all gases have low density in comparison to the densities of liquids. To illustrate,we note that 1 gram of liquid water at its boiling point has a volume very close to 1 milliliter. In comparison, this same 1 gram of water, onceevaporated into steam, has a volume of over 1700 milliliters. How does this expansion by a factor of 1700 occur? It is not credible that theindividual water molecules suddenly increase in size by this factor. The only plausible conclusion is that the distance betweengas molecules has increased dramatically.

Questions & Answers

Given that the elasticity of supply for a good is 2 and the percentage change in price is 45%.What is the percentage change in quantity supplied
Mbe Reply
state and explainfour function of a costumer service
Egba Reply
the circular flow model of the economy is a simplification showing how the economy works and the relationship between income,production and spending in the economy as a whole
Anna Reply
what is circular flow
Ntokozo Reply
what is economics?
Dorcas Reply
Economics is defined as the science that study human behaviour as a relationship between ends and scarce means which have alternative uses.
economics is a social science concerned with the production,distribution, and consumption of goods and services
in 2021 Amazon reduced the annual subscription fee for its prime membership service which provides free two_day shipping on many goods and other benefits, from $119 to $99. Zoppa consulting, an investment firm estimated that before the price reduction, prime had 62million subscribers globally. If so, what is the arc elasticity of demand for a prime membership.
Joan Reply
Differences between microeconomics and macroeconomics
tatiana Reply
Macroeconomics deal with the economy as a whole.that is an economy affect the firm ,government and the households eg.unemployment, whilst Microeconomics deal with the the decision making of households,firm and government separately.
what is Economics
Ebem Reply
the branch of knowledge concerned with the production, consumption, and transfer of wealth and has Influence by sociology!!!!
Economics is the study of how humans make decisions when they want to fulfil their requirements and desires for goods, services and resources.
Economics is the study how humans make decisions in the faces of scarcity.
economic is the study of how human make decision in the fact of scarcity.
Economics is a social science which study human behavior as a relationship between earn and scarce mean which have alternative uses
what is market structure
market structure in economics depicts how firms are differentiated and categorised based on types of goods they sell and how their operations are affected by external factors and elements.
what is economic theory
what is demand
Gooluck Reply
demand is the willingness to purchase something
demand is the potential ability or williness to purchases something at a particular price at a given period of time..
Demand refers to as quantities of a goods and services in which consumers are willing and able to purchase at a given period of time. Demand can also be defined as the desire backed by ability to purchase .
what is demand
John Reply
is the production of goods in scarcity
Demand refers to as quantities of a goods and services in which consumers are willing and able to purchase at a given period of time.
Demand refers to the quantity of goods and services that a consumer is willing and able to buy at a given price over a period of time
Do high interest rate in a country increase investment
what is demand of supply
music Reply
What is the meaning of supply of labour
Anthonia Reply
what is production?
Elizabeth Reply
Production is basically the creation of goods and services to satisfy human wants
importance of tertiary and example
Production is the process of producing goods and services to satisfy human needs and want.
under what condition will demand curve slope upward from left to right instead of normally sloping downward from left to right
Atama Reply
how i can calculate elasticity?
Tewekel Reply
A soccer field is a rectangle 130 meters wide and 110 meters long. The coach asks players to run from one corner to the other corner diagonally across. What is that distance, to the nearest tenths place.
Kimberly Reply
Jeannette has $5 and $10 bills in her wallet. The number of fives is three more than six times the number of tens. Let t represent the number of tens. Write an expression for the number of fives.
August Reply
What is the expressiin for seven less than four times the number of nickels
Leonardo Reply
How do i figure this problem out.
how do you translate this in Algebraic Expressions
linda Reply
why surface tension is zero at critical temperature
I think if critical temperature denote high temperature then a liquid stats boils that time the water stats to evaporate so some moles of h2o to up and due to high temp the bonding break they have low density so it can be a reason
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
Crystal Reply
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
Chris Reply
Difference between extinct and extici spicies
Amanpreet Reply
While the American heart association suggests that meditation might be used in conjunction with more traditional treatments as a way to manage hypertension
Beverly Reply
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get Jobilize Job Search Mobile App in your pocket Now!

Get it on Google Play Download on the App Store Now

Source:  OpenStax, General chemistry ii. OpenStax CNX. Mar 25, 2005 Download for free at http://cnx.org/content/col10262/1.2
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'General chemistry ii' conversation and receive update notifications?