Unit+5-+Ideal+Gas+Law

__Ideal Gas Law__ - Not all gases are ideal, but they have things in common which allow us to make useful predictions. - Ideal gas is a gas whose particles take up no space and have no intermolecular forces. - No gas behaves exactly like an "ideal gas", but it's a very useful way to approximate its behaviour.

__Formula__ - Since each gas acts the same way, we must define a constant: PV= nRT - In this formula; P= pressure, V= volume, n= number of moles, R= ideal gas constant, and T= temperature. - The following units are used for each part of the formula: P- kpa or atm, V- liters, n- number, R- 0.0821 L x atm/ mol x K, or 8.314 L x kPa/ mol x K, T- Kelvin - In order to figure out the given value in a problem you first need to plug in all the given values into the equation - You then use basic algebraic skills to solve for the unknown value

__Ideal Gas Constant__ - There are two values for the ideal gas constant (R): R = 0.0821 L x atm/ mol x K and R prime = 8.314 L x kPa/ mol x K - If in the equation you are given, the pressure is listed in atm, you use R; if it's in kPa, you use R prime. - In order to figure out the given value in a problem you first need to plug in all the given values into the equation - You then use basic algebraic skills to solve for the unknown value

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Example:__ Calculate the number of moles of gas contained in a 3.0 L. vessel at 300.0 K at a pressure of 1.50 atm

List your known values- V= 3.0L T= 300.0 K. P= 1.50 atm R= 0.0821 L x atm/ mol x K n= ?

PV = nRT Now plug the values into the equation

(1.50 atm) (3.0 L) = n ( 0.0821 L x atm/ mol x K) (300.0 K) n = 0.18 mol

__Example__: If pressure exerted by a gas at 25 degrees Celsius in a volume of 0.044 L. is 3.821 atm. how many moles of gas are present? List your known values- V=0.044 L. T= 25C or 298 K R= 0.0821 L x atm/ mol x K P= 3.821 atm n= ?

PV= nRT Now plug the values into the equations

(3.821atm)(0.044L) = n(0.0821 L x atm/ mol x K)(298 K) n = 0.007 mol

To see a video regarding an experiment using the ideal gas law go to: http://www.youtube.com/watch?v=NIZ-a3iu96s media type="youtube" key="NIZ-a3iu96s&hl=en" height="344" width="425"

To do some extra practice questions on the ideal gas law go to: http://www.chempractice.com/drills/java_Gas_Laws.php

To use an ideal gas law calculator go to: http://www.chemicool.com/idealgas.html

For more in-depth information on the ideal gas law go to: http://www.ausetute.com.au/idealgas.html