Ch. 4 Equilibrium and Thermodynamics Flashcards

1
Q

What is reversibility?

A

reactants are converted into products at the same time products are converted into reactants

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2
Q

IN a chemical reaction, the reaction rate is dependant upon?

A

reactant concentration.

The more product produced, the higher the decomposition rate

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3
Q

What is the rate equation of equilibrium?

A

Rate(forward) = Rate(reverse)

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4
Q

A reaction that is Spontaneous favors which direction?

A

Forward direction, making product

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5
Q

A reaction that is non-spontaneous favors which direction?

A

The reverse direction, to reactants

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6
Q

At equilibrium, what is ΔG

A

0

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7
Q

Keq is used to determine equilibrium constant, which is denoted as

A

products/reactants (coefficients are raised as powers)

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8
Q

When Keq favors the products

A

it will be a large value

Numerator greater than denominator

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9
Q

When Keq favors the reactants

A

It will be a smaller value

Denomenator larger than numerator

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10
Q

Which phases should not be included in the equilibrium expression?

A

Solids and pure liquids (water)

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11
Q

How would you calculate Keq for a reverse reaction?

A

this is the reciprocal of Keq, so 1/Keq

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12
Q

What are the units for Keq

A

moles/liter (Molarity)

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13
Q

Keq is negative when reactants are favored (T/F)

A

False.

Keq should never be negative

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14
Q

What is the reaction quotient?

A

A formula used to determine if a reaction is at equilibrium

It is also used to predict the direction in which the reaction will take to reach equilibrium

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15
Q

When Q < Keq

A

Ratio of products to reactants is lower than at equilibrium, products will want to form.

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16
Q

When Q >Keq

A

Raio of products to reactants is higher than t equilibrium, reactants will want to form.

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17
Q

When Q = Keq = 1

A

Equilibrium is reached

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18
Q

Calorimetry mimics which type of reaction?

A

combustion

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19
Q

1 calorie = how many Joules?

A

4.184

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20
Q

What is a calorie?

A

The amount of heat needed to raise the temperature of 1 gram of water by 1 degree Celcius (1cal/g°C)

21
Q

What is the specific heat capacity of water in Joules and calories

A

4.184 J/g °C

1 cal/g °C

22
Q

1 mL of water = how many grams?

A

1 gram

23
Q

What is heat capacity?

A

The heat required to raise the temperature of a system by 1 °C

24
Q

What is ΔH?

A

Enthalpy change (unit is kJ/mol)

25
Q

What is Enthalpy?

A

Heat absorbed/released by the system (heat transfer)

26
Q

Under what conditions would ΔH be negative?

A

Energy is released
Energy is produced
Heat is released
Heat is produced

27
Q

Under what conditions would ΔH be positive?

A

Energy is absorbed

Heat is absorbed

28
Q

Enthalpy(H) may also be used with the internal energy of a system. What is the formula?

A
ΔU = Q-W (or ΔU= Q+PΔV)
Q= heat transfer
W = work done by the system (PV)
29
Q

What is an endothermic process?

A

One that requires heat to work (ΔH positive)

30
Q

What does it mean if something has low entropy?

A

It has concentrated energy

31
Q

What does it mean if something has High entropy?

A

energy is spread out among the molecule

32
Q

Which entropy would be a favorable process?

A

Spontaneous, when ΔS is positive

33
Q

What unit is used for Entropy(S)?

A

J/K or J/K mol

34
Q

What is the formula for standard entropy(ΔS°)?

A

Products - reactants

35
Q

The Gibbs free energy formula is

A

ΔG = ΔH - TΔS

36
Q

What is Gibbs free energy?

A

The maximum amount of work that can be performed by a system consisting of one or more reversible reactions.
This allows us to know if a reaction is spontaneous

37
Q

What type of reaction is ΔH > 0?

A

Endothermic, heat needs to be added to the system

38
Q

What type of reaction is ΔH < 0?

A

Exothermic, heat is removed from the system

39
Q

What is ΔHf

A

Standard Enthalpy of formation (standard heat of formation), the enthalpy change associated with forming one mole of a compound from its elements under standard conditions (1 atm, 25°C)

40
Q

Enthalpy of any element in its elemental form is

A

0

41
Q

What is the formula for Bond dissociation?

A

ΔHrxn = ΔH°bonds broken - ΔH°bonds formed

42
Q

Forming bonds is what type of reaction

A

Exothermic, bonded atoms are more stable and lower in energy

43
Q

If ΔHrxn > 0 it is

A

Endothermic, energy is required

44
Q

For a reaction to take place it must overcome

A

Activation energy

45
Q

If ΔG < 0 during a reaction

A

it is spontaneous and exergonic

46
Q

If products are higher than reactants, energy must be absorbed to form products, how does this relate to ΔG?

A

non-spontaneous, ΔG is a positive and endergonic reaction

47
Q

What is the difference between Kinetic energy and Thermodynamics?

A

Kinetics focuses on the rate

Thermodynamics is about stability, spontaneity, and equilibrium

48
Q

Keq and ΔG have a _________ relationship

A

inverse