5: Chemical Energetics Flashcards
(17 cards)
What is activation energy?
The minimum amount of energy for particles to collide with for a successful reaction to take place.
What is bond energy?
The energy required to break one mole of the stated bond in the gas phase.
What is an endothermic reaction? [3]
A reaction which takes in energy (ΔH is positive). The reaction mixture and surroundings will decrease in temperature as heat energy is absorbed.
What is an energy profile?
A graph used to show the relative energy levels of reaction species (including reactants and products) as a reaction proceeds.
What is enthalpy change (∆H)? [2]
The heat energy change ,measured under a constant pressure.
What is an exothermic reaction?
An exothermic reaction is one that releases energy to the surroundings so the temperature of the surroundings increases (ΔH is negative).
What is Hess’s law?
The enthalpy change of a reaction is independent of the route taken.
What is mean bond enthalpy?
The enthalpy change when one mole of a specified covalent bond is broken, averaged out across a range of compounds.
What are standard conditions?
Solutions 1.0 mol dm-3 concentration, 298 K temperature and 100 kPa pressure.
What is the standard enthalpy change of neutralisation (∆neutHo)?
The enthalpy change when solutions of acid and alkali react together under standard conditions to produce one mole of water.
What is the standard enthalpy change of reaction (∆rHo)?
The enthalpy change when quantities of substances in standard states react completely under standard conditions.
What is the standard enthalpy of combustion (∆cHƟ)?
The enthalpy change when one mole of a substance is burned in excess oxygen under standard conditions.
What is the standard enthalpy of formation (∆fHƟ)?
The enthalpy change when one mole of a substance in its standard state is formed from its elements under standard conditions.
what is the standard enthalpy change of atomization
its the enthalpy change when 1 mole of gaseous atoms are formed from its elements in its standard state under standard conditions
what is the standard enthalpy change of vaporization
it is the energy needed to boil 1 mole of a liquid
what is the standard enthalpy change of solution
it is the enthalpy change when mole of solute is dissolved in a solvent to form an inifintely dilute solution under standard conditions
what is the standard enthalpy change of hydration of an anyhydrous salt
enthaly change when 1 mole of hydrated salt is formed from 1 mole of anyhdrous salt under standard conditions
