This preview shows pages 1–4. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Unformatted text preview: 1 Gases Todays Lecture 5.1 Early Experiments 5.2 The Gas Laws of Boyle, Charles and Avogadro 5.3 The Ideal Gas Law 5.4 Gas Stoichiometry 5.5 Daltons Law of Partial Pressures 1 Pressure a balloon expands when it is inflated with air, but what keeps it in its distended shape? its not easy to measure the total force exerted by a gas so instead we consider the gas pressure Pa m N area force Pressure 2 = = = Vacuum the unit of pressure in the SI system is N/m 2 called the pascal 2 h = 760mm Hg for standard atmosphere note that a pascal is a rather small pressure unit, so units like the standard atmosphere (atm), mm Hg (called torr) and the kilopascal (kPa) are more commonly used 1 atm = 760 mm Hg = 760 torr = 101.325 kPa 2 The Gas Laws in 1662, working with air, Robert Boyle discovered the first of the gas laws, now known as Boyles law using a Jshaped tube closed at one end, he studied the relationship between the pressure of the trapped air and its volume PV = k (this equation is called Boyles law), where P = pressure of the gas, V = volume of the gas and k = constant at a specific temperature for a given sample of air 3 rearranging Boyles law gives: y = mx + b (in this case, y = V, x = 1/P, m = k and b = 0) P k V = Boyles Law Therefore, a plot of V vs. 1/P should give a straight line of slope k and an intercept of zero (Figure 5.4(b)). Figure 5.4(a) shows a plot of P vs. V (again, note the inverse relationship between pressure and volume). in Hg) 50 100 20 40 slope = k (in 3 ) 4 P ( 20 40 60 50 P P 2 V 2 V 1/ P (in Hg) 0.01 0.02 0.03 V (b) (a) Fig. 5.4 3 Boyles Law (contd) note that Boyles law (PV = k) only approximately describes the relationship between pressure and volume for a gas (i.e....
View
Full
Document
This note was uploaded on 06/27/2009 for the course CHEM CHEM 121 taught by Professor Peggy during the Spring '09 term at Simon Fraser.
 Spring '09
 PEGGY
 Chemistry, Partial Pressure, Stoichiometry

Click to edit the document details