3832958
Description
Mind Map by Josh Bullock, updated more than 1 year ago
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Created by Josh Bullock
over 8 years ago
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Energetics
- Definitions
- Enthalpy Change
- The overall change in energy
in a reaction. Measured in KJ/mol.
- The overall change in energy
in a reaction. Measured in KJ/mol.
- Hess' Law
- The energy change in a
reaction is independent
of the route taken.
- The energy change in a
reaction is independent
of the route taken.
- Standard Enthalpy Change
- The amount of energy required with
one mole of a substance in their standard
states under standard conditions.
- The amount of energy required with
one mole of a substance in their standard
states under standard conditions.
- Standard Conditions
- 101kPa and 298K
- 101kPa and 298K
- Bond Enthalpies
- The energy required to break a bond.
This varies depending on the atoms
involved and the outside conditions.
- The energy required to break a bond.
This varies depending on the atoms
involved and the outside conditions.
- Enthalpy Change
- Equations
- q=mcΔT
- Enthalpy change of a reaction = energy
absorbed - energy released
- q=mcΔT
- Types of Reactions
- Endothermic Reactions
- Takes in energy from the surroundings. Has +ve ΔH.
- Takes in energy from the surroundings. Has +ve ΔH.
- Exothermic Reactions
- Emits energy to the surroundings. Has -ve ΔH.
- Emits energy to the surroundings. Has -ve ΔH.
- Endothermic Reactions
- Calorimetry
- You need to know the mass, temperature
change and the number of moles of the
reactants.
- You can just measure the
temperature change of reacting
solutions.
- For combustion, place the fuel in
a calorimeter and measure the
temperature change.
- Problems
- Some heat is absorbed by the container.
- Some heat is lost to the surroundings
(this always happens - even with
insulation).
- With flammable liquids:
- Some combustion may be incomplete.
- Some flammable liquid may evaporate before burning.
- Some combustion may be incomplete.
- Some heat is absorbed by the container.
- You need to know the mass, temperature
change and the number of moles of the
reactants.
- General Information
- Energy is required to break bonds
and energy is released when bonds
are formed.
- Enthalpy changes include
formation, combustion and reaction.
- Formation enthalpies for all
elements are zero.
- Energy is required to break bonds
and energy is released when bonds
are formed.
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