Chem4 - Thermodynamics

Question 1

what is an extensive property?

Answer 1

proportional to system size (volume, mols)

Question 2

what is an intensive property?

Answer 2

unrelated to system size (pressure, temperature)

Question 3

what is the actual definition of temperature?

Answer 3

measure of amount of molecular movement

Question 4

what is boltzmann’s constant(k)?

Answer 4

1.38e-23 JK-1(k)

Question 5

what is the equation for average kinetic energy per molecule in any fluid?

Answer 5

KE=3/2kT(k is boltzman constant, T is temp in kelvin)

Question 6

what is the equation for average KE per mol of molecule in a fluid?

Answer 6

KE=3/2RT

Question 7

how do you convert from Celsius to Kelvin?

Answer 7

add 273 to celsius

Question 8

what is a closed system?

Answer 8

can transfer energy but not mass

Question 9

what is an isolated system?

Answer 9

cannot transfer energy or mass

Question 10

what is a state function?

Answer 10

describes the state of a system in a path independent manner

Question 11

what is internal energy?

Answer 11

collective energy of molecules measured microscopically

Question 12

what is heat (q)?

Answer 12

describes spontaneous transfer of energy from warm to cold body

Question 13

what is the zeroth law of thermodynamics?

Answer 13

states that temperature exists

Question 14

what is conduction?

Answer 14

transfer of heat(thermal energy) via collisions and requires physical contact

Question 15

what is convection?

Answer 15

thermal energy tansfer in a liquid (think air/ocean currents)

Question 16

what is radiation?

Answer 16

thermal energy transfer using EM waves (white hot metal radiating heat)

Question 17

what is Work (w)?

Answer 17

any energy transfer that isn’t heat

Question 18

what is PV work?

Answer 18

work done by changes in pressure or volume

Question 19

what is the equation for PV work?

Answer 19

w=-PΔV

Question 20

PV work takes place when

Answer 20

gas expands against a force

Question 21

what is the first law of thermodynamics?

Answer 21

energy is constant in a systemΔE=q+w

Question 22

what is the equation for enthalpy?

Answer 22

ΔH=ΔU+PΔV

Question 23

if only PV work is performed

Answer 23

ΔH=qenthalpy change=heat transferred into system

Question 24

what is standard state?

Answer 24

reference form for a substance at temperature T & pressure of 1 bar

Question 25

what is standard enthalpy of formation?

Answer 25

reaction that produces 1 mol of a compound from its raw elements in their standard states

Question 26

to calculate standard enthalpy of formation (ΔHoreaction)

Answer 26

, subtract ΔH reactants from ΔHproducts

Question 27

what is the enthalpy change for an endothermic reaction?

Answer 27

positive ,  ΔH+

Question 28

what is the enthalpy change for an exothermic reaction?

Answer 28

negative,  -ΔH

Question 29

breaking bonds ___ energy

Answer 29

consumes, + delta H

Question 30

forming bonds ____ energy

Answer 30

releases, -delta H

Question 31

what is entropy(s)

Answer 31

tendency for disorder

Question 32

what is the 2nd law of thermodynamics?

Answer 32

entropy of the universe will never decrease

Question 33

is entropy a state function?

Answer 33

yes, path does not matter.

Question 34

what is the equation for gibb's free energy?

Answer 34

 ΔG= ΔH-TΔS

Question 35

what is delta G of an endergonic reaction?

Answer 35

positive ΔG

Question 36

what is delta G of an exergonic reaction?

Answer 36

#NAME?

Question 37

if ΔH is negative and ΔS is positive

Answer 37

always spontaneous

Question 38

if ΔH is positive, ΔS is negative

Answer 38

never spontaneous

Question 39

if both ΔH and ΔS have the same sign

Answer 39

spontaneity depends on temperature

Question 40

what is hess' law?

Answer 40

sum of each enthalpy change is equal to the total enthalpy change (adding up enthalpy changes, calculating with molar amounts)

Question 41

what is the actual definition for chemical equilibrium?

Answer 41

the rates of the forward and backward reaction rates are equal

Question 42

what is the equilibrium constant?

Answer 42

helps determine relative amounts of each substance at equilibrium

Question 43

what role do pure substances play in calculating the equilibrium constant?

Answer 43

none, they are given a value of 1 and do not contribue

Question 44

what is the reaction quotient?

Answer 44

identical to k except it does not represent the reaction at equilibrium

Question 45

if Q=K

Answer 45

reaction is at equilibrium

Question 46

if Q>K

Answer 46

reaction shifts to increase reactants(reverse rate is greater)

Question 47

if Q

Answer 47

reaction shifts to increase products(forward rate increases)

Question 48

what are the equations for free energy?

Answer 48

ΔG=ΔGo+RTln(Q)ΔGo=-RTln(K)

Question 49

if a reaction has K>1

Answer 49

reaction is spontaneous under the temp required to derive that value

Question 50

a second order reaction involves only __ reactant molecules

Answer 50

2