Chapter 8 -- Chemical Energies Flashcards Preview

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Flashcards in Chapter 8 -- Chemical Energies Deck (11):
1

Enthalpy change

Heat energy change measured at constant temp

(Usually 298K and 100kPa)

2

Standard enthalpy change of combustion

Enthalpy change measures at 100 kPa and specified temp (usually 298K) when one mole of substance is completely burned in oxygen

3

Enthalpy change of combustion equation

Q= mc🔼T

n=m/M

🔼H = - Q/n

4

Standard enthalpy change of neutralisation

🔼neut H

Enthalpy change when one mole of water is produced by neutralisation of acid with an alkali

5

Standard enthalpy change of neutralisation equation

Q= mc🔼T

amount of acid neutralised = amount of water formed

6

Q

Heat energy

7

Standard enthalpy change of formation

🔼f H

Enthalpy change when one mole of a substance is formed from its elements in their standard states

8

Hess’s law

Enthalpy change of a reaction is independent of the path taken in converting reactants into products - provided the initial and final conditions are the same in each case

9

Bond enthalpy

🔼B H

Enthalpy change when one mole of a bond in the gaseous state is broken

XY (g) —> X (g) + Y (g)

10

Mean bond enthalpy

Enthalpy change when one mole of a bond averaged out over many different molecules is broken

11

Enthalpy change of reaction using mean bond enthalpies

🔼r H

E(bonds broken) -E(bonds made)