reactivity 1.4- entropy and sponteneity

Question 1

entropy

Answer 1

distribution of available energy among the particles

Question 2

entropy of a system

Answer 2

the state of disorder of a system

Question 3

how will a system and its surroundings tend to move

Answer 3

from a state of high order (low entropy) to disorder (high entropy)

Question 4

entropy of univers

Answer 4

entropy of system + entropy of surroundings= always positive

Question 5

describe entropy in a reaction which changes solid to liquid or liquid to gas

Answer 5

increase in entropy or disorder
entropy is positive

Question 6

describe entropy in a reaction which changes 4 mol -> 2 mol

Answer 6

lower entropy, decrease in disorder entropy is negative

Question 7

describe entropy in a reaction which changes solid to gas

Answer 7

negative entropy

Question 8

how do you calculate the change in standar free energy at 298 K for a given reaction

Answer 8

1- calculate enthalpy change= sum enthalpy of formation for products - sum enthalpy of formation for reactants

2- caculate change in entropy = sum entropy of products - sum of entropy of reactants

3- calculate change in gibs free energy= enthalpy change - Temperature (in kelvin) * change in entropy/ 1000 (entropy always in KJ)

Question 9

if gibs free energy is positive

Answer 9

reaction is not spontaneuos

Question 10

if gibs free energy is negative

Answer 10

reaction is spontaneuos

Question 11

how do calculate the temperature in which a reaction becomes spontaneuos

Answer 11

=change in enthalpy/ (change in entropy/1000)(since units msut be in KJ)

temperautre will be given in kelvin

this calculation will give rise to the minimum temperature for a reaction to becme spontaneuos

Question 12

If enthalpy change is negative (exothermic)
entropy change is positive (increase in disrder)

Answer 12

gibs free energy will always be negative, reaction always spontaneous

Question 13

If enthalpy change is positive (endothermic)
entropy change is positive (increase in disorder)

Answer 13

gibs free energy is positive if, reaction not spontanuoes in cold (if T*change in entropy < change in enthalpy)

gibs free energy is negative if, reaction is spontaneuos at higher temperatures ( if T*change in entropy> change in enthalpy)

reaction more spontaneous at higher temperatures

Question 14

If enthalpy change is negative (exothermic)
entropy change is negative (decrease in disorder)

Answer 14

gibs free energy is positive when, not spontaneous reaction (T * change in entropy > change in enthalpy)

gibs free energy is negative when, spontaneous reaction, (T * change in entropy < change in enthalpy)

reaction more spontaneous at colder temperatures

Question 15

If enthalpy change is positive (endothermic)
entropy change is negative (decrease in disorder)

Answer 15

gibs free energy is always positive, reaction is never spontaneuos

Question 16

when is gibs free energy= 0

Answer 16

when reaction is at equilibrium