Enthalpy & Entropy

Question 1

Enthalpy change of reaction

Answer 1

EC that accompanies a reaction in the molar quantities shown in a chemical equation under SC w/ R + P in SS

Question 2

Enthalpy change of formation

Answer 2

EC when 1 mole of a compound is formed from its elements under SC w/ R + P in SS

Question 3

EC of combustion

Answer 3

EC when 1 mole of a substance reacts completely with oxygen under SC w/ R + P in SS

Question 4

EC of neutralisation

Answer 4

EC that accompanies the reaction of an acid by a base to form 1 mole of H2O under SC w/ R + P in SS

Question 5

Why is ΔHc not as accurate in experiments?

Answer 5

• heat loss to surroundings
• incomplete combustion
• evaporation of methanol from wick

Question 6

What is average bond enthalpy?

Answer 6

E required to break one mole of a specified type of bond in a gaseous molecule

Question 7

What does Hess’ law state

Answer 7

If a reaction can take place in 2 routes w/ starting + finishing conditions the same, the total enthalpy change is the same for each route

Question 8

Lattice enthalpy

Answer 8

Formation of 1mol of ionic lattice from gaseous ions

• used as a measure of strength of ionic bonding

Question 9

EC of atomisation

Answer 9

EC that takes place when 1 mole of gaseous atoms forms from the element in its SS

Question 10

EC of hydration

Answer 10

EC when 1 mole of isolated gaseous ions = dissolved in H2O -> 1 mole of aq ions under SS

Question 11

EC of solution

Answer 11

EC when 1 mole of a compound is completely dissolved in H2O under SC