chem Unit-2

Matter is anything that has mass and volume

• volume is the space an object takes 

• mass is the quantity of matter in an object 

    Matter is made up of tiny particles called atoms

    a Substance also called a chemical, is matter that has definite and uniform composition

   Matter classification

• Macroscopic: visible to the naked eye

• Submicroscopic: observing individual atoms

Properties of matter 

Physical properties: can be observed or measured without changing its composition. 

Ex: color, texture density physical state melting and boiling point… 

physical property like melting and boiling point can help determine its purity.

chemical property’s: the ability or inability of a substance to combine with others.

• to oberve it you must make changes to the substance

Ex: iron forming rust, copper turning green 

intensive vs. extensive properties

intensive: independent amount ex: density color 

extensive: dependent amount ex: mass volume length

states of matter

solid: 

• definite shape and volume 

• particles vibrate in a fixed position

• hard to compress 

• stong intermolecular forces 

ex: rocks metal ice… 

liquid: 

• matter that flows 

• constant volume 

• takes shape of container 

• particles slide past each other

• nearly incompressible 

• moderate intermolecular forces 

ex: water oil milk 

Gas: 

• no fixed shape or volume 

• low density 

• particles move rapidly and randomly 

• easily compressed 

• weak intermolecular forced 

ex: oxygen nitrogen hydrogen

Plasma: 

• ionized gas particals

• charged particals 

ex: sun and stars 

Changes in matter 

physical change: alters a substance without changing its composition

temp remains constant during the phase changes

chemical changes: the process where one or more substances transform into a new substance. 

    ex: decomposing, rusting, ordor change, gas producing, color change….

Evidence of a chemical change:

• creation of gas/bubbles

• formation of precipitate 

• release or absorption of energy

• change in temp

• color change

compound: two or more elements chemically combined with fixed ratio can be broken down chemically.

mixtures: two or more substanced physically combined with variable ratios 

    homogenous: uniform composition ( evenly mixed) and diffrent parts aren’t visible. 

ex: salt water and sugar and tea

    heterogeneous: un-even composition (not evenly mixed) and separate parts visible.

ex: oil and water and cereal and milk 

    homo: same 

    hetro: diffrent 

Conservation of Mass

The total mass before and after a chemical change reminds the same. 

Mass is conserved during both chemical and physical change

Mass is neither created nor destroyed

Mass of reactants equals mass of products.

Mass reactants = mass products

reactant + reactant = product 

law of definite proportions

A compound will always contain the same elements in a fixed ratio by mass

    if you get water it will have the same ratio of hydrogen to oxygen no matter the amount

law of multiple proportions

two elements can form more than one compound. they combine in a simple whole-number ratios 

    ex: 

            CO → 1 carbon + 1 oxygen 

            CO2 → 1 carbon + 2 oxygen 

so oxygen combines in a 2:1 ratio 

a simple whole number. 

seperation of mixtures 

1. Filtration

Used for: Separating an insoluble solid from a liquid
Example: Sand + water
How it works: Liquid passes through filter paper; solid stays behind.

2. Evaporation

Used for: Separating a soluble solid from a solution
Example: Salt from saltwater
How it works: The liquid evaporates, leaving the solid behind.

3. Crystallisation

Used for: Getting pure crystals of a soluble solid from a solution
Example: Sugar crystals
How it works: Heat the solution until it’s saturated, then cool it so crystals form.

4. Distillation

Used for: Separating a liquid from a solution OR two liquids with different boiling points
Example: Purifying water
How it works: Heat → lowest boiling point liquid turns into vapor → condenses back into liquid.

5. Fractional Distillation

Used for: Separating multiple liquids with close boiling points
Example: Crude oil separation
How it works: Fractionating column allows separation based on boiling point differences.

6. Chromatography

Used for: Separating dyes, inks, pigments
Example: Ink on filter paper
How it works: Different substances travel at different speeds on the paper.

7. Magnetic Separation

Used for: Separating magnetic materials from non-magnetic ones
Example: Iron filings + sulfur
How it works: Magnet attracts the magnetic substance.

 8. Sieving

Used for: Separating large solids from smaller solids
Example: Pasta + water, rice grains
How it works: Particles pass through holes smaller than their size.