CHEM-2

### Gas Testing

- Oxygen: relights glowing splint

- Hydrogen: squeaky pop with lit splint

- Carbon dioxide: turns limewater cloudy

- Chlorine: bleaches damp litmus paper

### Types of Mixtures

- Solution: solute dissolved in solvent (e.g. salt water)

- Emulsion: mix of two immiscible liquids (e.g. oil & water)

- Alloy: solid mixture of metals (e.g. brass = copper + zinc)

- Suspension: particles dispersed but not dissolved

### Distillation

- Separates liquids based on boiling points

- Simple distillation: one component (e.g. water from salt water)

- Fractional distillation: multiple components (e.g. crude oil)

### Crude Oil Separation

- Heated → vapors rise in fractionating column

- Different fractions condense at different heights

- Refinery gas, petrol, kerosene, diesel, bitumen...

Relative Atomic Mass (Aᵣ)

Weighted average of all isotopes.

✅ Formula:

Ar= (Isotope mass x Abundance) + (Isotope mass x Abundance) / 100

### Charges

METALS

• Group 1: +1 (e.g. Na⁺)

• Group 2: +2 (e.g. Mg²⁺)

• Group 3: +3 (e.g. Al³⁺)

NON METALS

• Group 5: –3 (e.g. N³⁻)

• Group 6: –2 (e.g. O²⁻)

• Group 7: –1 (e.g. Cl⁻)

Oxidation:

• Losing electrons

• Oxidation number goes up

  
  

Reduction:

• Gaining electrons

• Oxidation number goes down

REACTIVITY

• The closer to 0 or 8, the more reactive

NEVER SAY AMOUNT- SAY MASS OR VOLUME