Chemistry Unit 1

Formulae, Equations and Amount of Substance ALWAYS LOOK AT THE SYMBOL GIVEN (g OR dm³, etc.)
1. Empirical Formula: %/ram = x for each element, x/smallest value, then ajust
2. Ionic Equations: Write out full molecular formula, balance, separate into ions, look if soluble or not, then cancel spectator ions and re-write
3. Moles = mass/molar mass OR n=m/Mr
  1. For Gases: moles= volume(dm³)/Molar volume(24) OR n= v/Mv (24dm³molˉ¹)
  2. 4 Solutions: moles=concentration(moldmˉ³)Xvolume(dm³) OR n=cv REARRAGE: c(moldm³)=n/v WATCH OUT 4 CONVERTIONS cm³->dm³ 1cm³->0.001dm³ 1dm³->1000g
4. Calculations based on reactions
  1. To get Mass B from Mass A: mass A -> moles A -> moles B -> mass B
    1. Moles A -> Moles B: moles A x ratio B/A
5. Calculation of No. of Particles: No. molecules = Moles x Avogadro =>no. MOLECULES=nx6.02x10²³ =>no. IONS=no.molecules x No. of ions in the formula
6. Concentration of Solutions:
  1. amount of solute(moles)/volume(dm³) = moldmˉ³
  2. amount of solute (grams)/volume(dm³) = gdmˉ³
  3. [amount of solute (grams) / amount of solution {solute + solvent} (grams)x10^6] x 10^6/10^6=ppm TRY N WORK IT OUT SYSTEMATICALLY! USE X IF NEED BE!
    Anmerkungen:
    - video with explaining ppm in greater depth: http://www.youtube.com/watch?v=d6MxhXPmyes
7. Gas Volume Calculations
  1. To get Volume B from Mass A: mass A -> moles A -> moles of gas B -> volume of GAS B
    1. Moles A -> Moles B: moles A x ratio B/A
      1. Moles of gas B -> Volume of GAS B: moles B x molar volume
  2. Calculations for GASES ONLY: ratio B/A x mass A = volume of GAS B
    Anmerkungen:
    - For Calculations involving gases only, you can skip using the molar mass or volume because you divide and then multiply the same number. So: ratio B/A x Mass A = volume of gas Bis all the working that is needed!
8. Percentage yield (%) = (actual yield/theoretical yield) x 100
9. Atom economy = (Mr of product [that you want!!] x No. of formulae of it in the equation x 100) / sum of Mr of all reactants
Introduction to Organic Chemistry
Atomic Structure and The Periodic Table
Energetics
1. Exothermic reaction = bond breaking ∴ loses heat energy to surroundings ∴ change in enthalpy is negative (-ΔH)
2. Endothermic reaction = bond making ∴ gains heat energy from surroundings ∴ change in enthalpy is positive (+ΔH)
3. The activation energy is the energy required by certain chemicals to undergo a reaction
4. E=mcΔT
  Anmerkungen:
  - E=mcΔT E- Energy transfered m- mass c- specific heat capacity ΔT- change in temperature (Specific Heat Capacity- The energy in joules (j) needed to raise the temperature of 1Kg of a substance by 1 Kelvin)
5. ENTHALPY OF REACTION: is when the molar quantities as written in the equation react under standard conditions (1atm pressure + a stated temp of 298K)
6. ENTHALPY OF FORMATION: is the enthalpy change when 1 mole of a compound is formed from its elements under standard conditions
7. ENTHALPY OF COMBUSTION: is the enthalpy change when 1 mol of a substance if burnt completely in oxygen under standard conditions
8. ENTHALPY OF NEUTRALISATION: is the enthalpy change when an acid and base react to form 1 mol of water under standard conditions
9. HESS'S LAW: Law which states that the energy change in an overall chemical reaction is equal to the sum of the energy changes in the individual reacti
Bonding
Weak Points

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Chemistry Unit 1

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