Term 2~

Yay! It's term 2! Another wonderful term in HCI.

Our Science lesson still ROCKzzz !

First, we learnt about the Kinetic particle theory.

The kinetic particle theory states that all matter is made up of a large number of tiny atoms or molecules which are in continuous motion.

Three States of Matter

Solid:

The molecules of the solid are packed together tightly. They have strong attraction and repelling force among themselves which prevent them from collapsing.

That's why  the solid is always is fixed shape and have fixed volume. Solid cannot be compressed because there is very little gaps between the molecules.

Liquid:

The molecules of the solid are further apart than the solid. However, the molecules of the liquid can move around within the liquid.

That's why liquid do not have fix shape. The strong attraction force is still able to keep the liquid together so the liquid has a definite volume.

Gas:

The molecules of the gas are far apart. They move randomly with high speed.

Therefore, a gas do not have definite shape and volume and can be compressed easily due to the huge space between the molecules.

Then, we learnt about Element, Compound and mixture.

Elements:

Elements are the basic building block of matter , they may exist as atoms or molecule. It cannot be broken into simpler substance by any physical or chemical methods. The elements are grouped into a periodic table

Compound:

A compound is two or more elements that are chemically  joined  together. They are formed by fixed proportion and do not have the properties of its constituent elements.

Compound can be separated by chemical methods.

Mixture:

Elements in mixture is not combined together. Hence, mixture is not formed by fix proportion and have the properties of its constituent  elements. They can be broken down into simpler substances by physical methods.

Solution and Suspention

(a) is the molecules of a solution

(b) is the molecules of a suspension

Solution

a solution is a homogeneous mixture which the solute dissolves in a solvent completely.

There are three types of solutions we have learnt:

Dilute solution: There is little amount of solute dissolved inside the solvent.

Concentrated solution: There is a large amount of solute dissolved inside the solvent.

Saturated solution: Maximum amount of solute dissolved inside the solvent. At this stage no solute can be dissolved anymore.

Suspension: a suspension is a non-homeogenous mixture which the solute cannot be dissolve in the solvent.

Solubility: the amount solute that can be dissolved in a given amount of solvent.

Factors that will affect solubility:

• Type of solvent
• Type of solute
• Temperature

Rate of dissolving: the time taken for the solute to dissolve completely in solvent.

Factors that will affect the rate of dissolving:

• Size of the solute
• Temperature of solution
• Rate of stirring

What will happen if we get a mixture or a compound and we want to know what do they contain?

Yes, we can use Separation Techniques.

These are the different techniques used:

Paper Chromatography
It is used to separate a mixture which is based on the extent of solubility in a given solvent.

Filtration

It is used for mixtures that contain liquids and insoluble solids

Magnetic Attraction

Used to separate mixtures of magnetic and non-magnetic materials.

Simple distillation

It is used yo separate a solid-liquid solution.

Crystallization

It is used to recover pure soluble solid from a solution