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Y11 ATAR Chem Exam, Organic Chemistry, Gases & Solutions, Acids &…

- - - - strength
        
        increases from single to triple
      - length
        
        decreases from single to triple
    - - in any ion/molecule there are regions of high electron density
        
        lone pairs (unshared electron pairs)
        
        bonds (shared electron pairs)
      - electrons are arranged as far apart as possible
        
        due to electron–electron repulsion
        
        results in minimum energy for the system
    - - linear
        
        AX_2
        
        180º
        
        no lone pairs
      - trigonal planar
        
        (fidget spinner)
        
        AX_3
        
        120º
        
        no lone pairs
      - tetrahedral
        
        AX_4
        
        109.5º
        
        no lone pairs
      - pyramidal
        
        1 lone pair
        
        <109.5º (107º)
        
        AX_3E
      - bent (v-shape)
        
        2 lone pairs
        
        <109.5º (104.5º)
        
        AX_2E_2
  - - - measured from 0 to 4
    - - when 2 different species bond, the electrons are not shared evenly
        
        due to differing electronegativity
        
        has a bond dipole
    - - when 2 identical atoms bond covalently, electrons are shared equally
      - also called:
        
        pure covalent bond
        
        non-polar covalent bond
    - - uneven charge distribution
      - has a net dipole
      - molecule must:
        
        have 1 or more polar bonds
        
        not be symmetrical
- - - - mixture brought into electric field; charged particles will attract/repel and follow different paths
    - - simple
      - fractional
        
        for:
        
        separating liquids with different but close boiling points
        
        mixture heated; liquids vaporise and rise up fractionating column to different heights
        
        lowest BP: collected at top of column
        
        highest BP: collected at bottom of column
        
        industry uses
        
        oil refineries separating crude oil
        
        natural gas processing
        
        cryogenic air separation
      - for:
        
        separating 2 or more liquids
        
        separating liquids from a solid
      - requires difference in boiling point of at least 50ºC
      - mixture heated; liquid vaporises and rises up neck of flask
        
        vapour condenses back to a liquid, collected in a second vessel/flask
    - - for:
        
        immiscible (frenemy) liquids
        
        e.g. oil and water
      - separating by density & solubility
    - - separating by different particle size
    - - separating by difference in boiling point
  - - - lattice of cations surrounded by a sea of delocalised electrons
        
        electrostatic attraction holds lattice together
      - valence electrons are held very weakly, so can move freely
        
        electrons aren't associated with particular cations
      - properties:
        
        good conductors of electricity & heat
        
        electrons are free to move through the solid; high mobility
        
        lustrous
        
        malleable & ductile
        
        sufficient force can cause a layer of atoms to slide over each another
        
        delocalised electrons
        
        found as hard, dense solids
        
        (sophie metal-redman)
        
        high boiling & melting points
        
        due to strong electrostatic attraction
  - - - large 3D lattices of alternating cations & anions (metals & non-metals)
      - coordination number = number of oppositely charged ions directly surrounding a central ion
        
        can vary from 2-16, but usually 6
        
        (2, 4 or 6 are most common)
      - properties:
        
        pretty much always solid at room temperature
        
        made up of hard crystals
        
        (due to lattice structure)
        
        brittle
        
        when two layers of atoms pass over each other:
        
        ions of the same charge align
        
        this leads to repulsion, therefore fracturing
        
        high boiling & melting points
        
        large amounts of energy required to overcome strong bonds
        
        do not conduct electricity as solids
        
        good conductors of electricity when molten or aqueous
        
        molten:
        
        ions now mobile
        
        aqueous:
        
        soluble ionic compounds only!
        
        ions dissociate & become mobile
        
        fixed lattice = no mobile charged particles
        
        solubility:
        
        varying solubility in water
        
        insoluble in non-polar solvents
      - ionic solids:
        
        held in fixed position
        
        only allowed movement is vibration
        
        when formed from group 1&2 metals, usually white/colourless
        
        when formed from transition metals, usually coloured
      - called salts
      - simplest ratio of cation to anion is called 'formula unit'
    - - relatively strong bonds
      - formed from the transfer of electrons
  - - - properties:
        
        super hard & brittle
        
        brittle – if some bonds are broken, the lattice is placed under stress
        
        the lattice shatters, rather than distorting
        
        reasonably chemically inert
        
        chemical erectile dysfunction
        
        very high melting & boiling points
        
        does not conduct electricity (solids & liquids)
        
        no mobile electrons (all valence electrons are tied up in covalent bonds)
        
        exception: graphite
        
        insoluble in water & most solvents
        
        would need too much energy to re-arrange existing bonds
      - large, strong, continuous lattice structure
      - cannot be broken into discrete molecules
      - all atoms are covalently bonded to other atoms in the network
- - - - relative formula mass
      - percentage composition
      - relative molecular mass
- - - - gases exert pressure
        
        constant random motion = particles collide with container walls
        
        force/frequency of collisions increases = pressure increases
      - rapidly diffuse & mix
    - - compressible
    - - low density
      - occupies the container
  - - - negligible attraction & repulsion between particles
        
        particles are widely spaced– volume of particles in negligible compared to volume of gas
        
        particles in a gas have kinetic energy
        
        given by Ek = 1/2 x mv^2
        
        m = mass
        
        v = speed
        
        lighter gases = higher speeds
        
        avg. Ek of particles in gas is proportional to temperature, & same for all gases at that temperature
        
        particle collisions are elastic
        
        particles do not lose speed or energy as they collide
        
        as T increases, Ek increases
        
        at any temperature, gas particles will have a range of speeds
    - - Motion, Negligible, Widely (spaced), Kinetic, Temperature, Elastic
  - - - theoretical lowest temperature possible
        
        particles do not have enough kinetic energy to keep moving
      - 0K = -273.15ºC
    - - 10K = -263.15ºC
      - conversion: ± 273.15
  - - - Pressure & Volume are inversely proportional
        
        increasing the pressure of a gas decreases volume as the particles are pressed closer together
        
        P1 x V1 = P2 x V2
      - condition
        
        constant temperature & gas quantity
    - - Temperature & Volume are directly proportional
        
        increasing temperature of a gas increases volume as particles have greater kinetic energy & move further apart
        
        V1/T1 = V2/T2
      - condition
        
        constant pressure & gas quantity
    - - PV/T = k
        
        temperature in Kelvin
        
        k = constant
      - condition:
        
        constant gas quantity
      - states that the ratio between pressure, volume and temperature of a gas equals a constant.
      - P1V1/T1 = P2V2/T2
  - - - particles occupy volume & experience forces of attraction
    - - forces of attraction: negligible
      - particle volume: negligible
    - - theoretically, an ideal gas at 0K would occupy zero volume
      - real gases condense when cooled/compressed. ideal gases can't because intermolecular forces are negligible.
- - - - pressure (P)
      - temperature (T)
      - amount of gas particles (moles)
    - - "equal volumes of gases at the same temperature and pressure contain equal numbers of particles"
  - - - n = V/22.71
        
        n = number of moles
        
        V = volume (Litres)
  - - - P = pressure (kPa)
      - V = volume (L)
      - n = number of moles
      - R = universal gas constant (formula sheet)
      - T = temperature (K)
- - - - does the dissolving
      - (german accent) vere has the solute vent (its dissolved)
    - - being dissolved
        
        sol-OOOOOH IM BEING DISSOLVED
      - easily dissolved in water = hydrophilic
      - insoluble in water = hydrophobic
      - types
        
        ionic
        
        (highly polar)
        
        polar (–OH, C=O, –NH)
        
        non-polar (insoluble in water. long c chains)
    - - homogenous (gay)
  - - - hydrocarbons with –OH groups have both polar & non-polar properties
  - - - ion-dipole bonds form
    - - organic molecules
        
        usually non-polar
        
        usually hydrophobic
      - ethanol
        
        dissolves in
        
        water
        
        because of polar –OH end group
        
        organic solvents
        
        because of non-polar –CH3 end
  - - - energy of bonds they form w/ water is LOWER than energy between bonds of the solute
        
        energy differences explains varied solubility of ionic substances
    - - strength of ionic bonds
        
        depends on
        
        arrangement of ions
        
        size of ions
        
        charges of ions
      - strength of ion-dipole attraction
        
        depends on
        
        size of ions
        
        charges of ions
        
        geometry of ions (if polyatomic)
      - temperature
        
        solids in liquids:
        
        temp increases, solubility increases
        
        gases in liquids:
        
        temp increases, solubility decreases
  - - - rate of dissolving = rate of recrystallisation
    - - solution contains more than max. allowable amount of dissolved solute for that temperature
      - achieved by
        
        dissolving solute in hot solvent & then cooling
      - unstable state
      - crystals form
- - - - e.g. sodium, calcium, potassium
  - - - 100% dissociation/ionisation
      - ionic solids; strong acids
      - high conductivity
    - - significantly less than 100% dissociation/ionisation
      - weak acids; weak bases
      - low conductivity
    - - no conductivity
- - - - solute mass (mg) / solution mass (kg)
        
        solute mass (g) x 10^6 / solution mass (g)
    - - solute mass (g) / solution volume (L)
    - - moles of solute / solution volume (L)
        
        c = n/V
  - - - expressed in mol L^ –1
- - - - H in formula
      - produces H^+ in solution
    - - OH in formula
      - produces OH^ – in solution
  - - - e.g. NH_3 and CO_3
        
        ammonia & carbon trioxide
    - - not all bases are soluble in water; his definition has been modified to include insoluble bases
    - - e.g. HCl(g) + NH_3(g) > NH_4Cl(s)
        
        hydrochloric acid + ammonia > ammonium chloride
    - - H_3O^+ is the hydronium ion
    - - most oxides formed between oxygen & a non-metal are acidic/neutral
      - oxides formed between oxygen & a metal are basic/amphoteric
  - - - e.g. water
        
        HCl + H_2O > Cl^ – + H_3O^+
        
        hydrochloric acid + water > chloride + hydronium ion
        
        NH_3 + H_2O > NH_4^+ + OH^ –
        
        ammonia + water > ammonium + hydroxide
    - - H_2O + H_2O <–> H_3O^+ + OH^ –
        
        water + water <–> hydronium ion + hydroxide
      - water therefore conducts electricity to a small extent
  - - - base 100% dissociates
      - group 1 & 2 oxides
      - group 1 & 2 hydroxides
    - - some base dissociates
      - group 1 & 2 carbonates
      - group 1 & 2 hydrogen carbonates
      - ammonia (NH_3)
- - - - polyprotic acid: donates 2 or more protons
      - monoprotic acid: donates 1 proton
- - - - every change in pH by 1 unit is a tenfold change in [H^+]
- - - - if enthalpy decreases, a corresponding amount must be released into the surroundings
- - - - sufficient energy to disrupt bonds
        
        minimum energy needed = activation energy
      - suitable orientation to form new bonds
- - - - sometimes called heat of reaction
      - enthalpy changes an be in the form of heat, light, sound, electrical etc.
      - ∆H = H(products) – H(reactants)
        
        change in enthalpy = enthalpy of products – enthalpy of reactants
      - enthalpy changes in chemical processes are much larger than in physical processes (e.g. boiling, melting, dissolving)
      - values for ∆H usually given in kJ per mole
  - - - if a reaction is carried out in solution, the solvent is part of the surroundings
- - - - weak intermolecular forces – not much energy required to separate molecules from each other
    - - no mobile particles
      - some ionise (if polar), but it isn't common
    - - malleable – weak intermolecular forces
    - - generally non-polar
    - - smelly :(