Volume,+Temperature+and+Pressure...Are+they+related?

**What is Pressure?**
Pressure is a basic physical property of a gas. It is measured as the force exerted by the gas per unit area on its surroundings.

**What is Volume?**
Volume is the amount of space that something takes up. Solids have a fixed volume and shape. Liquids have a fixed volume but take the shape of their container. Gases take the volume and shape of their container.

**What is Temperature?**
Temperature is most commonly thought of as how hot or cold something is. More precisely, temperature is related to the measure of the average kinetic energy of the particles of a sample of matter. This matter can be in any state. Matter is made up of atoms and molecules, and these particles are constantly moving. (Only at 0 Kelvin does all motion stop. This is known as absolute zero, and represents the lowest temperature possible.) media type="file" key="Dry Ice.wmv"

Key Concepts

 * An Ideal Gas (perfect gas)is one which obeys [|Boyle's Law] and [|Charles' Law] exactly.
 * * An Ideal Gas is modelled on the Kinetic Theory of Gases which has 4 basic postulates: || * Real Gases deviate from Ideal Gas Behaviour because: ||
 * # Gases consist of small particles (molecules) which are in continuous random motion
 * 1) The volume of the molecules present is negligible compared to the total volume occupied by the gas
 * 2) Intermolecular forces are negligible
 * 3) Pressure is due to the gas molecules colliding with the walls of the container || # at low temperatures the gas molecules have less kinetic energy (move around less) so they //do// attract each other
 * 4) at high pressures the gas molecules are forced closer together so that the volume of the gas molecules becomes significant compared to the volume the gas occupies

3. Under ordinary conditions, deviations from Ideal Gas behaviour are so slight that they can be neglected 4. A gas which deviates from Ideal Gas behaviour is called a //non-ideal gas//. ||

**When is a gas not an ideal gas?**  In general this occurs in two situations: 1. Extremely high pressures (the intermolecular spaces are very small and they can collide with each other) 2. Extremely low temperatures (the molecules will move slow and they might feel the attraction and...well you know what happens after that)

**The Relationship between P, V, and T:**
The relationship between gas volume (V), pressure (P), and temperature (T) can be expressed by the ideal gas law:

PV = nRT where P = pressure of gas, V = volume occupied, T = temperature, n =.moles, and R = gases constant (R = 0.0821 L atm K-1 mol-1 if Pressure is in atmospheres(atm), Volume is in litres(L), Temperature is in Kelvin(K) In simpler terms, if volume is constant, an increase in temperature results in a proportional increase in pressure. media type="custom" key="3051404" If pressure is constant, an increase in temperature results in a proportional increase in volume. Inversely, if volume is decreased and pressure remains constant, temperature must decrease. Basically, pressure and volume are directly proportional to temperature and inversely proportional to each other.


 * Find out more **: go to http://www.explorelearning.com/index.cfm!!

[|take the test on concepts and definitions]
Your Own Balloon:**
 * Activities:

Blow up two similar balloons. Let them sit for several minutes until their temperatures match the room temperature. Measure the room temperature with a thermometer. Measure the circumference of each balloon at the widest spot with a piece of string or a measuring tape. Record these measurements. Place one balloon in a refrigerator or freezer, and keep the other balloon at room temperature as a control. Measure the temperature inside the refrigerator or freezer with the same thermometer. Leave the balloon in the refrigerator or freezer for about an hour. Remove the balloon and measure the circumference around the widest spot as quickly as possible. Compare this measurement to the measurement made before the balloon was placed in the refrigerator! Allow the balloon to warm back up to room temperature and measure again! Also measure the control balloon. Now compare the numbers. What is the relationship between temperature and volume? Does the pressure stay the same inside of the balloon? Why or why not? Use the control balloon to make sure the refrigerated balloon did not leak. How would you do this?