Chemistry Unit 3 Equations

All equations and 2 example questions, bond energy example question not included due to them being large and requiring alot of extra information.

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  • Created by: richard
  • Created on: 15-05-13 14:28
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  • Chemistry Unit 3 Equations
    • Specific Heat Capacity
      • How much energy is needed to increase the temperature of 500 g of lead from 20ºC to 45ºC? The specific heat capacity of lead is 128 J/kg ºC.
        • mass of lead = 500/1000 = 0.5kg temperature change = 45-20 = 25c energy needed = 0.5 x 128 x 25 = 1600j or 1.6kj
      • E =m x c x t
        • m = mass
        • c = specific heat capacity
        • t = temperature change
    • Bond Energy Calculations
      • You will be given bond energies for example h-h = 436kj per mole.
        • Energychange = sum of bonds broken - sum of bonds made
    • Titration Equation
      • M1 x V1 divided by N1 = M2 x V2 divided by N2
        • E.G. 25.00cm of an unknown strength HCL reacted with 38.90cm of 0.100 mole per cm solution of Na OH calculate the concentration of HCL?
          • HCL + NaOH = NaCL +H2O
            • So where m1 is unknown v1 = 25.00cm n1 = 1  m2 = 0.100 moles per cm v2 =38.9cm and n2 = 1
              • M1 = M2 x V2 x N1 divided by N2 x V1
                • M1 = 0.100 x 38.90 x 1 divided by 1 x 25.00
  • How much energy is needed to increase the temperature of 500 g of lead from 20ºC to 45ºC? The specific heat capacity of lead is 128 J/kg ºC.
    • mass of lead = 500/1000 = 0.5kg temperature change = 45-20 = 25c energy needed = 0.5 x 128 x 25 = 1600j or 1.6kj

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