IDEAL GAS VS REAL GAS

IDEAL GAS	REAL GAS
PV=nRT	(P + an2)(V - nb)=nRT                           V2
Condition : Low Pressure, High temperature	Condition: Low temperature, high Pressure
When pressure decrease, Volume increase      ·         Distance between gas molecules far          apart      ·         The volume of gas too small                        compared  to volume of the container      ·         Thus volume of gas molecules is                negligible	When pressure increase, volume decrease      ·         The distance between gas molecules        become closer      ·         Volume of gas become significant and       cannot be neglect
When temperature increase      ·         Kinetic energy of gas molecules                 increase      ·         Molecules move faster and able to             overcome the intermolecular forces           between molecules      ·        Thus, the attractive forces between           gas molecules can be neglect.	When temperature decrease      ·         Kinetic energy of gas decrease      ·         Gas molecules are close to each                other and move slower      ·         The attractive forces between gas              molecules become significant

 In Van Der Waals equation:6

n term of pressure (P + an2)                                        V2	In term of volume (V - nb)
At low temperature, average kinetic energy of gas decrease	At high pressure, volume of container decrease
Gas move slower and intermolecular forces become significant	Gas molecules are much closer and volume of gas molecules become significant
The frequency of collision on the wall container decrease
As a result: P real< P ideal	As a result: Vreal > V ideal
The factor an2/V2 is added to the P term correct the pressure of real gas which is smaller than ideal gas	The factor nb is substracted from the V term to correct the volume of real gas which is larger than ideal gas.
a is constant to correct for intermolecular forces	b is constant to correct for volume occupied by gas molecules
The higher the a value, the stronger the attractive forces between gas molecules	The higher the b value, the bigger the volume occupied by gas molecules

More explaination about ideal gas and real gas :

Common polyatomic ions

Intramolecular forces and intermolecular forces

Intramolecular and intermolecular forces

Analogy to understand about intramolecular forces and intermolecular forces.

We have six towels—three are purple in color, labeled hydrogen and three are pink in color, labeled chlorine. We are given a sewing needle and black thread to sew one hydrogen towel to one chlorine towel. After sewing, we now have three pairs of towels: hydrogen sewed to chlorine. The next step is to attach these three pairs of towels to each other. For this we use Velcro (grey colour as label intermolecular attraction) as shown above .

So, the result of this exercise is that we have six towels attached to each other through thread and Velcro. Now if I ask you to pull this assembly from both ends, what do you think will happen? The Velcro junctions will fall apart while the sewed junctions will stay as is. The attachment created by Velcro is much weaker than the attachment created by the thread that we used to sew the pairs of towels together. A slight force applied to either end of the towels can easily bring apart the Velcro junctions without tearing apart the sewed junctions.

Exactly the same situation exists in molecules. Just imagine the towels to be real atoms, such as hydrogen and chlorine. These two atoms are bound to each other through a polar covalent bond—analogous to the thread. Each hydrogen chloride molecule in turn is bonded to the neighboring hydrogen chloride molecule through a dipole-dipole attraction—analogous to Velcro. We’ll talk about dipole-dipole interactions in detail a bit later. The polar covalent bond is much stronger in strength than the dipole-dipole interaction. The former is termed an intramolecular attraction while the latter is termed an intermolecular attraction.

So now we can define the two forces:

Intramolecular forces are the forces that hold atoms together within a molecule. Intermolecular forces are forces that exist between molecules.

of towels sewn and Velcroed representing bonds between hydrogen and chlorine atoms, illustrating intermolar and intramolar attractions

Flow chart how to predict the polarity of molecules

Use this flow chart to help you to determine polarity of the compound

Good luck