project in it2n ... chemisty

Robert Boyle (1627-1691)Birth: 1660, IrelandPublished book on Gases: 1680."The Sceptical Chymist"

Boyle studied the compressibility of gases in 1660. In his experiments he observed "At a fixed temperature, the volume of a gas is inversely proportional to the pressure exerted by the gas." The experiment is simple: (see figure on left).

Formula:

or PV=k

The equation states that product of pressure and volume is a constant for a given mass of confined gas as long as the temperature is constant. For comparing the same substance under two different sets of condition, the law can be usefully expressed as

P1V1=P2V2The equation shows that, as volume increases, the pressure of the gas decreases in proportion. Similarly, as volume decreases, the pressure of the gas increases. 

• P is pressure of the gas• V is volume of the gas• k is a constant, and has units of

force times distance

Example:1. Freon-12, CCl2F2, is used in refrigeration

systems. What is the new volume (L) of a 8.0 L sample of Freon gas initially at 550 mm Hg after its pressure is changed to 2200 mm Hg at constant T?

Set up a data table:Conditions 1 Conditions 2 P1 = 550 mm Hg P2 = 2200 mm HgV1 = 8.0 L V2 = ?

 An  animation  of Boyle's Law,  showing  the  relationship  between  volume  and pressure when mass and temperature are held constant.

Solution for Boyle’s Law V2: P1V1 = P2V2

V2 = V1 x P1 P2 V2 = 8.0 L x 550 mm Hg = 2.0 L 2200 mm Hg pressure ratio decreases volume

2. A sample of gaseous nitrogen in a 65.0 L automobile air bag has a pressure of 745 mm Hg. If this sample is transferred to a 25.0 L bag at the same temperature. what is the pressure of the gas in the 25.0 L bag?

Solution: It is often useful to make a table of the information provided.Initial conditions Final conditions P1 = 745 mm Hg P2 = ?V1 = 65.0 L V2 = 25.0L

Therefore,P2 = P1V1

V2P2 = [745 mm Hg][65.0 L]

25.0 L

P2 = 1937 mm Hg