Chemistry (UNFINISHED!!!)

all modules

Homogenous Mixture

Uniform mixture composition throughout; not composed of different substances (e.g air)

Heterogenous Mixture

Not a uniform mixture composition throughout; composed of different substances (e.g concrete)

What are the physical properties?

Size
Boiling Point
Condensation Point
Water Solubility
Magnetisim
Melting Point
Electrical Conductivity
Density
Immiscibility

Inorganic Chemicals

Not carbon derived. Includes all salts (e.g sodium chloride, magnesium bromide, carbon dioxide, sodium carbonate)

Organic Chemicals

Carbon derived (e.g. alkanes, alkynes, alcohols, aldehydes, ketones)

Ionic Compound

Cation⁺ and Anion^-

Binary Compounds:

Cation named first, anion ends in ‘-ide’
(E.g Sodium Chloride)

Covalent Compounds

Between nonmetals.
1. More electronegative element last

2. Last element suffix ‘ide’

3. Prefix denoting the number of atoms

Covalent Compound Prefixes

Mono

Di

Tri

Tetra
Penta

Hexa
Hepta
Octa

Nona

Deca

Basic Radicals

Bicarbonate HCO₃^-
Hydroxide OH^-

Nitrite NO₂^-

Nitrate NO₃^-

Sulphate SO₄^-2

Carbonate CO₃^-2

Phosphate PO₄^-3

Ammonium NH₄⁺

Cation

Positively charged species; atom lost one or more electrons.

Anion

Negatively charged species; atom gained one or more electrons.

Electronegativity

Tendency to attract bonding electrons.

Group Classifications

Group 1: Highly reactive, low mpt/bpt, low density

Group 2: Shiny, silvery in colour, low density, somewhat reactive

Group 18: Colourless, odourless, inert and singular

Ionic Network

A network (lattice/crystal) of positive and negative ions bonded by strong electrostatic forces between two oppositely charged ions

Ionic Network Properties

Hard (electrostatic force attraction)

Brittle/non-malleable (force causes fracturing due to ion repulsion)

High mpt/bpt (strong ionic bonds)

Metallics

‘Sea’ of delocalised electrons surrounding positive nuclei of metal atoms; nucleus close together.

Metallics Properties

Malleable (electron movement prevents fracturing)

Conduct electricity (electron flow)

Strong (electrostatic forces)

Covalent Bonds

Involves sharing of electrons between two or more non-metals to create a noble structure (e.g water)

Strong intramolecular forces holding atoms together

Weak intermolecular forces (between neighbouring molecules), resulting in low mpt/bpt

Covalent Networks

Atoms bonded in a 3D network structure.

High mpt/bpt (e.g diamond, graphite, silicon dioxide)

Percentage Composition Formula

The Mole

A very big number (6.022 x 10²³) called Avagadro's number.

Acid + Base

= Salt + Water

E.g Hydrochloric Acid + Sodium Hydroxide → Sodium Chloride + Water

HCl_(aq) + NaOH_(aq) → NaCl_(aq) + H₂O_(l)

Acid + Metal Carbonate

= Salt + Water + Carbon Dioxide

E.g Hydrochloric Acid + Copper (II) Carbonate → Copper (II) Chloride + Water + Carbon Dioxide

2HCl_(aq) + CuCO_3(s) → CuCl_2(aq) + H₂O_(l) + CO_2(g)

Acid + Metal

= A salt + Hydrogen

E.g Hydrochloric Acid + Magnesium → Magnesium Chloride + Hydrogen

2HCl_(aq) + Mg_(s) → MgCl_2(aq) + H_2(g)

Decomposition

Metal Carbonate –(heat)--> Metal Oxide + Carbon Dioxide

E.g Copper (ii) Carbonate → Copper (ii) Oxide + Carbon Dioxide

CuCO_3(s) –(heat)-- CuO_(s) + CO_2(g)

Precipitation

= Solution 1 + Solution 2 → Solid ppt + Solution 3

E.g Lead (ii) Nitrate + Sodium iodide → Lead (ii) iodide + Sodium nitrate

Pb(NO₃)_2(aq) + 2NaI_(aq) → PbI_2(s + 2NaNO_3(aq)

Metal + Oxygen

= Metal Oxide

E.g Magnesium + Oxygen = Magnesium Oxide

2Mg_(s) + O_2(g) → 2MgO_(s)

Combustion - 'Complete'

Hydrocarbon + Oxygen (INXS) → Carbon Dioxide + Water

E.g Propane + Oxygen → Carbon Dioxide + Water

C₃H_8(g) + 5O_2(g) → 3CO_2(g) + 4H₂O_(l)

Incomplete Combustion

Hydrocarbon + Oxygen (LR) → Carbon Dioxide + Water + 'Various' (e.g Soot)

E.g Octane + Oxygen → Carbon + Carbon Dioxide + Water 

C₃H_18(g) + 5/2O_2(g) → 7C_(s) + CO_2(g) + 9H₂O_(l)

Displacement

Metal 1 + Salt-Solution 1 → Metal 2 + Solution 2

E.g Zinc + Copper (ii) Sulphate → Copper (ii) + Zinc Sulphate

Zn_(s) + CuSO_4(aq) → Cu_(s) + ZnSO_4(aq)

Molarity

n_(gas)

1 mol IDEAL gas

0℃ - 22.71 (STP)

25℃ - 24.79 (SLC)

Dilution

Measures of Concentration - mol/L to g/L

• mol/L * MM = g/L

• mol/L * g/mol = g/L

Measures of Concentration - g/L to %w/v

• g/L / 10 = g/100mL

• g/100mL = %(w/v)

Measures of Concentration - mol/L to ppm

• Multiply molarity by MM to get g/L

• Multiply by 1,000 to convert g/L to mg/L (ppm)

Measures of Concentration - %(V/V)

Percentage volume represents the concentration of a solute in a solution where the solute and the solution are both liquids.

Boyle’s Law

At constant temperature, the volume of the gas increases as the pressure decreases. The volume of the gas decreases, pressure increases.

P₁V₁ = P₂V₂  || Where (P)ressure and (V)olume

BLT - Boyle's, Constant Temperature

Charles's Law

At constant pressure, volume of gas increases as temperature of gas increases and volume decreases when temperature decreases.

CP - Charles, Constant Pressure

Gay-Lussac's Law

Fixed gas at constant volume, pressure increases linearly with temperature.

Combined Gas Law

Avagadro's Law

Equal volume of gases at same temperature and pressure contain equal numbers of molecules. 

n_(gas) = Vol(L) / MV(L)

Ideal Gas

Ideal gas contains a large number of molecules which travel in a random, rapid motion - moves in straight lines until hitting a wall.

A gas is only ideal if its molecules occupy a negligible amount of the container.

Ideal Gas Law

PV = nRT

P = Pressure | V = Volume | n = mol | R = 8.314K^-mol^-1 | T = Temperature

(Boyles + Charles + Avagadro)

Room Temperature State of Matter

Unlisted: Solid

Bromide and Mercury: Liquid

Oxygen, Nitrogen, Fluoride and Chlorine + Group 18: Gas

Chemical Reactions

	Physical Change	Chemical Change
New substances formed?	No	Yes
Bonds broken	No (intermolecular attraction weakens)	Yes (intramolecular bonds broken)
Energy needed	Relatively small	Relatively large
E.g boiling versus electrolysis of water	2 single covalent bonds - intramolecular	Bonds broken
Equation	H2O(l) –(heat)--> H2O(g)	2H2O(l) –(electricity)--> 2H2(g) + O2(g)

Advantages / Disadvantages of molymod kit?

Ad:

• Visualised relative kinetic energy

• Breaking of bonds/rearrangement

• Double covalent bonds

Dis:

• Can’t see energy

• Electron movement

• Not to scale

AATSI Detoxification

Outer Cycad Fruit

• Edible through anaerobic fermentation (decomposition) - soaking + burying which eliminates macrozamin toxin (carcingoenic)

Inner Cycad Seed

• Leaching process - cut open and washed with running water - removes cyasin carcinogen

Rate of Reaction

Rate which reactants are used up OR rate at which products are formed

Factors affecting Rate of Reaction

• Temperature

• Reactant surface area

• Concentration of reactants

• Catalysts

Exothermic Reactions

Release heat.

Intermolecular Bonding

Occurs between covalent molecules. Three types:

• Dispersion (weakest)

• Dipole-dipole (Between atoms of different electronegativities)

• Hydrogen bonding (strongest, between H-O, H-N, H-F)

q = mCΔT

Q = Joules

M = Mass (g)

C = Specific heat capacity (4.18)

ΔT = Temperature Change

Metals in Water (Active)

• React with H₂O to form a metal hydroxide and H₂.

• Vigorous in any water - store in oil

• Sodium + water → sodium hydroxide + hydrogen gas

  
  

Less Active Metals in Water

• Group 2 and 3 metals react less explosively in water

• Magnesium + Water → Magnesium Hydroxide + Hydrogen Gas

Even Lesser Active Metals in Water

• Not with hot water but steam

• Aluminium + Steam → Aluminium oxide and Hydrogen Gas

Metals and Acids

• Most metals (unreactive silver/gold or chemically inert like platinum excluded) react with acids, including dilute HCl and H₂SO₄ to produce a salt + hydrogen. More reactive react more vigorously.

Half Equations

In many chemical equations, electrons are lost (oxidisation) and electrons are gained (reduction) between one species in the reaction and the other.

Oxidisation Half Equation

Mg_(s) → Mg⁺² + 2e^-

Reduction Half Equation

2H⁺_(aq) + 2e^- → H_2(g)

Galvanic Cells

Voltaic cells; convert chemical energy into electrical energy. Allows for external flow of electrons. Used for reactivity testing.

Zn_(s) → Zn_(aq)⁺² + 2e^- | OXIDATION half equation.

Cu⁺² + 2e^- → Cu_(s) | REDUCTION half equation.

How do you determine the Theoretical Voltage of a Galvanic Cell?

1. Find electron ions on the reduction table.

2. Determine which ion will be the one that oxidises (closest to K⁺)

3. Flip equation and change the sign of its voltage.

4. Leave the reduction half equation and voltage as is.

5. Add each half equation and voltage to determine the EMF of the cell.

Oxidation States Rules

1. Elements are given an oxidation state of zero

2. The oxidation number of a simple ion is the same as its charge

3. Hydrogen = +1 when forming compounds with non-metals. Hydrogen = -1 in metal hydrides

4. For polyatomic ions the oxidation numbers must add up to the charge on the ion

Oxidation State Golden Rule

If an oxidation number increases, then oxidation is occurring.

If an oxidation number decreases, then reduction is occurring.