Gibb’s Energy & Thermodynamics

Question 1

What does entropy describe?

Answer 1

the dispersion of energy

Question 2

What is a spontaneous process?

Answer 2

occurs without ongoing external intervention

Question 3

Can spontaneous reactions be slow?

Answer 3

yes

Question 4

What is entropy? (definition)

Answer 4

a thermodynamic function that increases with the number of equivalent ways to arrange the energy among components of the system to acheive a particular overall state

Question 5

How is entropy mathematically described? What are the variables?

Answer 5

S=klnW

S is entropy, k is a constant (1.38x10^-23 JK^-1), W is the # of equivalent energy arrangments in the system (microstates)

Question 6

Explain why water has greater entropy than ice using microstates?

Answer 6

more ways to distribute the energy in water than ice because they can more more, therefore more microstates

Question 7

What is the second law of thermodynamics?

Answer 7

for any spontaneous process the entropy of the universe increases

Question 8

How do non-spontaneous reactions effect the entropy of the universe?

Answer 8

do not increase or decrease it

Question 9

What is the formula for the change in entropy?

Answer 9

deltaS=Sfinal-Sinitial

Question 10

If entropy increases how does temperature change?

Answer 10

increases

Question 11

What increases entropy?

Answer 11

adding more particles, melting, sublimation, evaporation

Question 12

What is the formula for the entropy of the universe?

Answer 12

Suniverse=Ssys + Ssurr

Question 13

How does the entropy of the surroundings change for exo/endothermic reactions?

Answer 13

exothermic increases the entropy of surroundings

endothermic decreases the entropy of surroundings

Question 14

At a constant temperature and pressure how can you find the entropy of the surroundings?

Answer 14

deltaSsurr=-deltaHsys/T (kelvin)

Question 15

How can you find the change in entropy of the universe?

Answer 15

deltaSuni=deltaSsys - deltaH/T

Question 16

How is Gibb’s free energy related to entropy?

Answer 16

deltarG=deltarH - TdeltarS

Question 17

If enthalpy is exothermic and the entropy increases what is the sign for gibb’s free energy?

Answer 17

always negative no matter the temperature

Question 18

If enthalpy is endothermic and the entropy decreases what is the sign for gibb’s free energy?

Answer 18

always positive, no matter the temperature

Question 19

If enthalpy is exothermic and the entropy decreases what is the sign for gibb’s free energy?

Answer 19

negative at a low temperature and posititve at a high temperatureq

Question 20

If enthalpy is endothermic and the entropy increases what is the sign for gibb’s free energy?

Answer 20

posititve at a low temperautre and negative at a high temperautre

Question 21

How can you calculate deltarS0?

Answer 21

the sum of coefficients multiplied by standard molar entropies of the products minus the sum of coefficients multiplied by standard molar entropies of the reactants

like standard enthalpy

Question 22

What is the enropy of a pure crystal at 0K?

Answer 22

0

Question 23

How does molar mass contribute to entropy?

Answer 23

heavier atoms have a higher entropy, larger noble gases have a higher entropy

Question 24

How does molecule complexity relate to entropy?

Answer 24

more complex molecules have a higher entropy

Question 25

What are the methods to calculate deltarG0?

Answer 25

using standard Gibb's energy of formation, table is only valid for 298K, calulate standard enthalpy and standard entropy and have T, similar to hess law

Question 26

At standard state conditions what is Q?

Answer 26

1

Question 27

If deltarG0 is greater than 0, what is the relationship between Q and K?

Answer 27

Q is greater than K

Question 28

If deltarG0 is less than 0, what is the relationship between Q and K?

Answer 28

Q is less than K

Question 29

If deltarG0 is equal to 0, what is the relationship between Q and K?

Answer 29

Q is equal to K

Question 30

How can you calculate deltarG under non standard conditions?

Answer 30

deltarG=deltarG0 + RTlnQ

Question 31

How can you find deltarG0 if you know K?

Answer 31

deltarG0=-RTlnK

Question 32

If you have two K's and two temperautre what formula can you use?

Answer 32

ln(K2/K1)=-deltarH0/R(1/T2-1/T1)