290449
Description
Mind Map by Madeleine.Dc, updated more than 1 year ago
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Created by Madeleine.Dc
over 10 years ago
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Enthalpy Change Practical
- Non-Combustion Reaction
- Spontaneous reaction at room temperature
- Salt + Water
- Enthalpy change of
solution
- Enthalpy change of
solution
- Acid + Alkali
- Enthalpy change
of neutralisation
- Enthalpy change
of neutralisation
- Salt + Water
- Used for both exothermic and endothermic reactions
- Spontaneous reaction at room temperature
- Combustion Reaction
- Specifically measures the heat given out (exothermic)
- Method
- Measure the mass
of the burner before
and after
- Thermometer records
the temperature of the
known mass of water
- Thermometer records
the temperature of the
known mass of water
- Measure the mass
of the burner before
and after
- Limitations
- Very Inaccurate
- Huge losses of heat
- Radiation from flame
and calorimeter
- Conduction through
copper calorimeter
- Convection from the
flame gases passing by
calorimeter
- Radiation from flame
and calorimeter
- Huge losses of heat
- Very Inaccurate
- Used for the comparison of the
heat output of different fuels
- If same burner and set-up is used
- If same burner and set-up is used
- Specifically measures the heat given out (exothermic)
- Q = mcΔT
- Calculation
- For both experiements
- Calculate the change in
temperature
- Apply mcΔT, using the
heat capacity of and mass
of water
- Calculate the number
of moles of reactants
- Alcohol for combustion reaction,
use mass = mr x mole
- Q x 1/moles of burner
- Put into KiloJoules
- Put into KiloJoules
- Solution, use
moles = conc x vol
- Alcohol for combustion reaction,
use mass = mr x mole
- Calculate the number
of moles of reactants
- Apply mcΔT, using the
heat capacity of and mass
of water
- Calculate the change in
temperature
- For both experiements
- Calculation
- Free Energy
- ΔG = ΔH - TΔS
- ΔS(system) = S(products) - S(reactants)
- Entropy
- Measure of the disorder in a system
- Measure of the disorder in a system
- Entropy
- Use the temperature
in Kelvin
- 273 + T in degress
- 273 + T in degress
- Hess's law cycles can also be applied
- ΔS(system) = S(products) - S(reactants)
- If ΔG is positive the reaction
is not spontaneous at 298K
- ΔG = ΔH - TΔS
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