ENTHALPY

Question 1

STANDARD ENTHALPY CHANGE OF FORMATION

Answer 1

the enthalpy change when 1 mole of a compound is formed from its elements in their standard states under standard conditions

Question 2

ENTHALPY CHANGE FORMULA

Answer 2

enthalpy change = (total energy to break bonds) - (total energy released forming bonds)

Question 3

Q = MC(delta)T

Answer 3

heat energy change = mass of solution x 4.18 x temperature change
enthalpy = q/moles

Question 4

STANDARD CONDITIONS FOR ENTHALPY

Answer 4

25 degrees

100 kPa

Question 5

STANDARD ENTHALPY CHANGE OF COMBUSTION

Answer 5

enthalpy change when 1 mole of a substance is completely burned in oxygen to make CO2 and H2O under standard conditions

Question 6

WHAT IS THE ENTHALPY CHANGE OF A REACTION

Answer 6

The heat change of a reaction at a constant pressure (under standard conditions)

Question 7

STANDARD ENTHALPY CHANGE OF NEUTRALISATION

Answer 7

enthalpy change when an acid and an alkali form 1 mole of water under standard conditions

Question 8

What is an endothermic reaction and an example

Answer 8

one that absorbs energy from the surroundings

Thermal decomposition of calcium carbonate

Question 9

What is an exothermic reaction and an example

Answer 9

one that releases energy to the surroundings

combustion of ethane

Question 10

What is bond dissociation enthalpy

Answer 10

the energy needed per mole to break attractive forces in a bond (ONLY OCCURS IN GASEOUS COMPOUNDS)

Question 11

What is calorimetry used for

Answer 11

to work out enthalpy change of reactions

Question 12

What’s Hess’ law

Answer 12

The total enthalpy change of a reaction is independent of the route taken

Question 13

Hess’ cycle of formation layout

Answer 13

Reactants products

    elements in standard states

Question 14

Hess’ cycle of combustion layout

Answer 14

Reactants/elements products

                 combustion products