Chap 9: continued

Question 1

Lattice energy.

Answer 1

energy associated with forming a crystalline lattice
of alternating positive and negative ions, from ions in the gas phase

remember: ions have to be in gas phase.

Question 2

Pressure-Volume work

Answer 2

is the work that is done by the expansion or compression of a liquid.

Question 3

How is change in enthalpy different from change in internal energy.

Answer 3

Internal energy is the intrinsic energy of a system and can be measured with reference to something in the system (i.e chemical bonds), while DH is the heat change at constant pressure due to some chemical process.

Question 4

Explain the difference between exothermic and endothermic reactions in terms of the relative strengths of the bonds that are broken and the bonds that are formed.

Answer 4

In an exothermic reaction, more energy is released when the bonds are formed in the products than is used to break the bonds in the reactants. It’s the other way around in an endothermic reaction.