Thermodynamics

Question 1

What is kinetics?

Answer 1

Speed of a reaction

Question 2

What is thermodynamics?

Answer 2

Energy changes associated with a reaction

Question 3

What is the first law of thermodynamics?

Answer 3

The conversion from one form to another however energy cannot be changed or destroyed

Question 4

What is enthalpy?

Answer 4

First type of energy
-change in enthalpy must be measured however enthalpy cannot be measured

Question 5

(ΔH) ?

Answer 5

The amount of heat energy given out or taken in as a reaction proceeds at a particular temperature
Reaction can be EXOTHERMIC or ENDOTHERMIC
Units= kJ mol-1

Question 6

What is the difference between endothermic or exothermic?

Answer 6

Endothermic- positive
Exothermic- negative

Question 7

What is Hess’s law of constant heat summation?

Answer 7

The enthalpy change from reactants to products is the SAME regardless of which route is taken
-ΔH1+ ΔH2= ΔH3
^Third one can always be worked out if the other 2 are known

*total enthalpy change must be identical, whether it is a direct/indirect route

Question 8

Pros and cons of enthalpy?

Answer 8

Pros;
-taking an entire molecule/ bringing an entire molecule back together without having to do any practicals etc
Cons;
-results= average/ mean
-could be attatched to other things

Question 9

What is entropy?

Answer 9

-high entropy= high disorder
-entropy can be increased by heating or providing more space for the molecules
-entropy of a liquid is higher than a solid, and a gas is higher than a liquid
-as T=0 is neutral entropy, then entropy is usually positive but not always

Question 10

What is Gibbs free energy?

Answer 10

-at a constant temp and pressure = enthalpy is 0
-it is another way for expressing entropy at a constant temp

ΔG= TΔS