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chem > Chem 2 exam 4 > Flashcards

Chem 2 exam 4 Flashcards

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1
Q

chemical thermodynamics

A

relationship between energy and the extent of chemical reactions

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2
Q

how many laws are there in themodynamics

A

3

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3
Q

What does the First Law of Thermodynamics state?

A

The total energy of the universe is constant. Energy cannot be created or destroyed; it can only be converted from one form to another or transferred between a system and its surroundings.

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4
Q

What is the equation representing the First Law of Thermodynamics?

A

he equation is:

ΔE=q+w
Where:

ΔE = Change in the system’s internal energy.
q = Heat exchanged between the system and its surroundings.
w = Work done by or on the system

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5
Q

What are the two forms of energy transfer mentioned in the First Law of Thermodynamics?

A

Heat (q): Energy transferred as heat between the system and its surroundings.
Work (w): Energy transferred as work between the system and its surroundings.

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6
Q

Can energy be created or destroyed according to the First Law of Thermodynamics?

A

No, energy cannot be created or destroyed. It can only change form (e.g., from chemical to thermal energy) or be transferred between the system and its surroundings.

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7
Q

What is the Thermodynamic Universe as described in the First Law of Thermodynamics?

A

The thermodynamic universe consists of two parts:

The system – the part of the universe being studied.
The surroundings – everything outside the system.
Energy can flow between these two, but the total energy remains constant.

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8
Q

What does

ΔE=q+w mean in terms of energy flow?

A

The system’s total energy change (
ΔE) is the sum of the heat (
q) transferred to or from the system, plus the work (
w) done by or on the system.

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9
Q

What is a spontaneous process?

A

A process that occurs without continuous external influence once started.

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10
Q

Can spontaneous processes occur in reverse?

A

No, processes that are spontaneous in one direction are not spontaneous in the reverse direction.

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11
Q

What experimental factors affect spontaneous processes?

A

Temperature and pressure.

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12
Q

How does temperature affect spontaneity?

A

Examples include ice melting or water freezing, where temperature can drive spontaneity.

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13
Q

spontaneous temp for ice melting is

A

T>0

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14
Q

dpontaneous temp for water freezing is

A

T<0

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15
Q

What do spontaneous reactions do?

A

hey move the reaction mixture toward equilibrium.

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16
Q

What do non-spontaneous reactions do?

A

They move the reaction mixture away from equilibrium

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17
Q

Does spontaneous mean fast?

A

No, spontaneous reactions are not always fast.

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18
Q

What is Enthalpy Change (∆H)?

A

The heat transferred between system and surroundings during a constant-pressure process:
ΔH=ΔE+PΔV

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19
Q

What is Enthalpy (H)?

A

Enthalpy is the system’s total heat content:
H=E+PV (internal energy + work from pressure/volume).

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20
Q

What is Entropy (S)?

A

Entropy is the degree of molecular randomness (order/disorder) in a system.

21
Q

What is Entropy Change (∆S)

A

The change in order/disorder between initial and final states:
ΔS=S final−S initia

22
Q

Chemical reactions involve changes in _____ and _____

A

enthalpy and entroopy

23
Q

what infuences whether a process is spontaneous or not

A

enthalpy and entropy

24
Q

The change in a system’s entropy (∆S) is the difference between

A

the system’s final entropy and its initial entropy:
∆S = Sfinal - Sinitial

25
Q

Entropy formula

A

∆S = Sfinal - Sinitial

26
Q

less entropy means

A

less randomness, S<0, reaction decreases numbe of as particles

27
Q

more entropy means

A

more randomness, reaction increases number of gas particles, S>0

28
Q

What is a reversible process?

A

A reversible process returns the system and surroundings to their original states by exactly reversing the process, maximizing work done by the system on surroundings

29
Q

Can a truly reversible process be achieved?

A

No, a truly reversible process is theoretical and requires infinitesimally small steps to keep the system in equilibrium.

30
Q

What is required for reversible heat flow between system and surroundings?

A

Heat will flow reversibly only if there is an infinitesimally small temperature difference between the system and surroundings.

31
Q

What is an irreversible process?

A

An irreversible process cannot be simply reversed to restore the system and surroundings to their original states.

32
Q

Can a spontaneous process be reversible?

A

No, any spontaneous process is irreversible.

33
Q

Give an example of an irreversible process.

A

Getting gas back into the right side of a cylinder by only replacing the partition is an irreversible process.

34
Q

What is an isothermal process?

A

An isothermal process occurs at a constant temperature, meaning there is no temperature change.

35
Q

How is entropy change (∆S) calculated for an isothermal process?

A

For an isothermal process, entropy change is the heat transferred (q) divided by the absolute temperature
ΔS= T/q
​

36
Q

In an isothermal process, what remains constant?

A

The temperature (T) remains constant during the process.

37
Q

How does heat transfer affect the entropy of the surroundings?

A

Exothermic: ∆Hsys < 0, entropy of surroundings increases (∆Ssurr > 0).
Endothermic: ∆Hsys > 0, entropy of surroundings decreases (∆Ssurr < 0).

38
Q

What is the relationship between heat and enthalpy in a constant pressure process?

A

q sys =ΔH sys
​

39
Q

How does entropy change in the surroundings during an exothermic reaction?

A

Entropy of surroundings increases (∆Ssurr > 0).

40
Q

How does entropy change in the surroundings during an endothermic reaction?

A

Entropy of surroundings decreases (∆Ssurr < 0).

41
Q

What does the Second Law of Thermodynamics state about entropy?

A

In a spontaneous process, total entropy (∆S) of the system and surroundings always increases:
ΔS universe=ΔS sys+ΔS surr>0

42
Q

What happens to entropy in a reversible process?

A

What happens to entropy in a reversible process?
A: For a reversible process,ΔS universe=ΔS sys+ΔS surr>0

43
Q

What is the sign of ∆Stotal in a spontaneous reaction?

A

ΔS total>0 for a spontaneous reaction

44
Q

What does ∆Stotal = 0 indicate?

A

Δ𝑆total =0 means the reaction mixture is at equilibrium.

45
Q

What does a negative ∆Stotal indicate?

A

ΔS total<0 means the reaction is non-spontaneous in the forward direction but spontaneous in the reverse direction.

46
Q

spontaneous reaction occurs slowly if

A

it has a high activation energy

47
Q

spontaneous reactions can be

A

exothermic or endothermic

48
Q

all exothermic reaction will have a _____ H

A

negative

49
Q
A

chem (6 decks)

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