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Flashcards in Physical Chemisty Deck (13):
1

Enthalpy change of formation

Change in enthalpy when one mole of a substance in the standard state is formed from its pure elements u see the same conditions

2

Enthalpy change of combustion

Enthalpy change which occurs when one mole of the compound is burned completely in oxygen under standard conditions and with everything in the standard state

3

Standard conditions of temperature and pressure

298K
100KPa

4

Bond enthalpy

Amount of energy needed to break one mole of the stated bond

5

Enthalpy change of reaction

Enthalpy change when the reaction occurs in the molar quantities shown in the chemical equation, under standard conditions

6

Enthalpy change of neutralisation

Enthalpy change when am acid and alkali react together under standard conditions to form 1 mole of water

7

Average bond enthalpy

Energy needed to break one mole of bonds in the gas phase averaged over many different compounds

8

Hess’ law

Regardless of the multiple stages of a reaction, the total enthalpy change for the reaction is the sum of all the changes

9

Catalyst

Lower activation energy by providing alternative pathways for the bonds to be broken and remade. The catalyst is left unchanged

10

Heterogeneous catalysts

In a different physical state to reactants
Reaction happens on surface of the catalyst and increasing area means more can react

11

Homogenous catalyst

Same physical state as the reactants
Usually is a aqueous catalyst, works by making an intermediate species which then reacts to from products and reform the catalyst

12

Catalyst used to make ethanol

Phosphoric Acid

13

Le chataliers prunciple

If you change the concentration, pressure or temperature of a reversible reaction, you tend to alter the position of equilibrium