Concepts of Thermodynamics -ALL NOTES

Question 1

What is potential energy?

Answer 1

-Stored energy

Question 2

What are examples of potential energy?

Answer 2

-Raised weight, stretched rubber band, charged battery

Question 3

What are examples of kinetic energy?

Answer 3

-Boiling water, desk lamp, buzzing bee

Question 4

What is kinetic energy?

Answer 4

-Energy of moving objects

Question 5

What is thermodynamics?

Answer 5

-The science of energy interconversion

Question 6

What is an isolated system?

Answer 6

-An isolated system cannot exchange energy or matter with its surroundings

Question 7

What is a closed system?

Answer 7

-A system where mass cannot transfer but energy can

Question 8

What is an open system?

Answer 8

-An open system can exchange both energy and matter with its surroundings

Question 9

What is the zeroth law of thermodynamics?

Answer 9

-If two systems are in thermal equilibrium with a third system the two original systems are in thermal equilibrium with each other

Question 10

What is the first law of thermodynamics?

Answer 10

-Energy can not be created or destroyed- only transformed from one form to another

Question 11

What is the equation for the conservation energy?

Answer 11

-deltaU= Q-W

Question 12

What does it mean if the Q is positive in the first law of thermodynamics ?

Answer 12

-Heat is added to the system so is an endothermic process

Question 13

What does it mean if the Q is negative in the first law of thermodynamics ?

Answer 13

-Heat is released from the system so exothermic process

Question 14

What is an SI unit?

Answer 14

-International System of Units equal to a joule or cal/kcal

Question 15

What is 1 calorie?

Answer 15

-Heat needed to raise the temperature of 1 gram of water 1oc at standard pressure?

Question 16

What is heat capacity?

Answer 16

-Amount of heat required to raise a substances temperature by 1 kelvin

Question 17

What is specific heat capacity?

Answer 17

-Amount of heat required to raise 1 gram of a substance by 1 kelvin

Question 18

What is the symbol for heat capacity?

Answer 18

-C

Question 19

What is the symbol for specific heat capacity ?

Answer 19

-Cs

Question 20

What is enthalpy?

Answer 20

-The measurement of energy in a thermodynamic system

Question 21

What is the equation for enthalpy?

Answer 21

-deltaH = deltaE + delta(PV)

Question 22

What can you assume about enthalpy equation in cells?

Question 23

What happens to enthalpy in an endothermic process?

Answer 23

-

Question 24

What happens to enthalpy in an exothermic process?

Answer 24

-

Question 25

What is the second law of thermodynamics ?

Answer 25

-The universe is always moving towards maximum disorder

Question 26

What is entropy ?

Answer 26

-Measure of disorder

Question 27

What is the third law of thermodynamics?

Answer 27

-At absolute zero (0K) the entropy of a perfect, crystalline substance is zero

Question 28

Why does entropy equal 0 at absolute zero?

Answer 28

-There is a perfect crystalline structure so all vibrations and atomic movements stop

Question 29

What temperature is absolute zero in degrees Celsius?

Answer 29

-273.15 oc

Question 30

What does G stand for?

Answer 30

-Gibbs free energy

Question 31

What is Gibbs free energy?

Answer 31

-Energy available to do work and the spontaneity of a reaction

Question 32

What does H stand for?

Answer 32

-Enthalpy (KJ mol-1)

Question 33

If delta G is negative is the reaction spontaneous?

Answer 33

-Yes, in a forward reaction only

Question 34

If delta G is zero is the reaction spontaneous ?

Answer 34

-Yes, at equilibrium, can proceed in either direction

Question 35

If delta G is positive, is the reaction spontaneous ?

Answer 35

-No, unless coupled with an energetically favourable reaction

Question 36

What is free energy of formation?

Answer 36

-The free energy change which results from 1 mol of substance prepared from its elements at standard temperature and pressure

Question 37

How do you calculate free energy of formation?

Answer 37

-Delta G of formation of products minus delta G formation of reactants

Question 38

What is the standard enthalpy change of a reaction?

Answer 38

-The heat transferred by a chemical reaction or process under standard conditions

Question 39

What is bond dissociation energy?

Answer 39

-The enthalpy change per mol in the gas phase when a bond is broken

Question 40

What does D stand for?

Answer 40

-Bond dissociation enthalpy

Question 41

Is bond dissociation enthalpy positive or negative?

Answer 41

-Positive as bond breaking is an endothermic process

Question 42

What is the standard entropy change of a reaction?

Answer 42

-The difference in standard entropy between the products and reactants of a system ubnder standard conditions

Question 43

If a reaction is at equilibrium, what happens at E on the graph?

Answer 43

-G rises if the reaction proceeds in either direction

Question 44

What does K stand for?

Answer 44

-The composition of a reaction mixture when it comes to equilibrium

Question 45

What are the features of using K?

Answer 45

-Used in heterogenous reactions, must be associated with a specific temperature and equation of the reaction

Question 46

What is Q?

Answer 46

-Measures the composition of the reaction mixture as the reaction progresses, not at equilibrium

Question 47

If K is more than Q, what reaction proceeds?

Answer 47

-Forward

Question 48

If K is less than Q what reaction proceeds?

Answer 48

-Reverse

Question 49

If K=Q what reaction proceeds?

Answer 49

-both-at equilibrium

Question 50

What is Le Chatelier's principle ?

Answer 50

-When a change is made to a system in dynamic equilibrium, the system responds to minimise the effect of the change