3.7 - Entropy ( disorder of a system)

Question 1

Entropy?

Answer 1

the degree of freedom of a system where particles can move freely in any direction to create a higher entropy

Question 2

In a solid?

Answer 2

the atoms are in fixed positions with no freedom to move so the entropy is low

Question 3

In a liquid?

Answer 3

the atoms are free to move in any direction but must stay close together, so entropy is greater than a solid

Question 4

In a gas?

Answer 4

atoms are free to move in any direction + to any position so the entropy is high

Question 5

Symbol forentropy?

Answer 5

S

Question 6

Units?

Answer 6

JK -1

Question 7

Delta S?

Answer 7

Entropy change of the products - entropy change of the reactants

CH4(g) + 2O2(g) —– CO2 + 2H2O (l)

Question 8

2nd law of thermodynamics?

Answer 8

entropy will always tend to increase in any isolated system that is not in equilibrium
Any disordered system that is not in equilibrium will increase its degree of freedom unless work is done to it.

Question 9

Gibs free energy?

Answer 9

Delta G
most reactions = exothermic
99 % of reactions
considering enthalpy + entropy, it’s possible to tell whether a reaction will spontaneously occur

Question 10

Units for gibs free energy?

Answer 10

KJ mol -1
J mol -1

Question 11

conditions?

Answer 11

If delta G is negative, the reaction will occur spontaneously, but if delta G is positive, it will not occur spontaneously + requires energy

If delta S ( entropy) is positive, increasing the temp will cause - T delta A to become more negative until Gibs free energy is negative

If delta S is negative, then decreasing the temp will cause - T delta S to become smaller and less positive

Question 12

Delta G?

Answer 12

Delta H - T delta S