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semester 2 chemistry revisions > Lecture 1 > Flashcards

Lecture 1 Flashcards

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1
Q

What is energy?

What is work?

A

ENERGY is the ability to do WORK.

Work is defined as the DISTANCE moved against an opposing FORCE.

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2
Q

Equation for work?

A

FORCE X DISTANCE = WORK

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3
Q

What is the first law of thermodynamics?

A

Energy is constant cannot be created nor destroyed by any physical and chemical changes.

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4
Q

When will a reaction not occur?

A
  1. Not enough energy= ACTIVATION ENERGY

2. Orientation of collisions= Correct molecules have to collide with each other.

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5
Q

What is the ENTHALPY CHANGE OF REACTION (ΔH)?

A

The difference in the change in energy between bond energies of reactants and products.

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6
Q

What is ΔHo?

A

Heat RELEASED or ABSORBED during a chemical reaction at STANDARD conditions.

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7
Q

Equation for ΔHo?

A

∆Ho = HProducts – Hreactants

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8
Q

Can you measure the actual enthalpy of a substance?

A

NO- only measure enthalpy change.

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9
Q

What are the standard conditions of a element?

A

1 Atmosphere

25oC

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10
Q

What is the standard conditions of a compound?

A

Gaseous Substance= Pressure of 1 Atmosphere.
Pure substance in solid/ liquid= State it would have at 1 Atmosphere.
Substance in solution= Concentration of 1 M.

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11
Q 
EXOTHERMIC REACTION:
What happens to the products? 
What happens to heat?
Example:
Temperature of the system...
ΔH?
A

Products contain LESS energy than reactants.
Products more stable.
Heat is RELEASED to the surroundings.
Eg. Burning/ Respiration.
The temperature of the system will be observed to INCREASE.
∆H is NEGATIVE for an exothermic reaction.

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12
Q 
ENDOTHERMIC REACTION:
What happens to the products? 
What happens to heat?
Example:
Temperature of the system...
ΔH?
A

Products contain MORE energy than the reactants. Products less stable.
Heat is TAKEN IN from the surroundings.
E.g photosynthesis.
Temperature of system will DECREASE.
∆H is POSITIVE for an endothermic reaction.

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13
Q

Is bond breaking endothermic/ exothermic?

A

ENDOTHERMIC

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14
Q

Is bond making endothermic/ exothermic?

A

EXOTHERMIC

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15
Q

What is entropy?

Entropy Symbol?

A

ENTROPY measures the amount of energetic DISORDER in a system.

S

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16
Q

Equation for Change in Entropy?

A

∆S = Sfinal - Sinitial

17
Q

Equation of the total change in entropy?

A

∆Stotal = ∆Ssystem + ∆Ssurroundings

18
Q

What is the second law of thermodynamics?

A

Entropy tends to a maximum.

19
Q

List examples of increases in entropy:

A 
SOLIDS MELTING 
LIQUIDS BOILING
NUMBER OF MOLECULES INCREASING.
IONIC SOLIDS DISSOLVE
TEMPERATURE INCREASE
20
Q

What is Gibbs Free Energy?

A

The energy from a reaction FREE to do WORK.

21
Q

Equation for Gibbs Free Energy:

A

ΔG = ΔH – TΔS

22
Q

What does ΔG have to be for the reaction to be spontaneous, energy needed to be inputted and for the system to be at equilibrium?

A

ΔG < 0 Reaction will be SPONTANEOUS.
ΔG > 0 Reaction needs ENERGY INPUT to happen.
ΔG = 0 The system is in EQUILIBRIUM.

23
Q

What is an Exergonic Reaction?

A

ΔG NEGATIVE

24
Q

What is an Endergonic Reaction?

A

ΔG POSITIVE

25
Q

When is ΔG always negative?

A 
ΔH= -
ΔS= +
26
Q

When is ΔG positive or negative?

A 
ΔH= -
ΔS= -
ΔH= + 
ΔS= +
27
Q

When is ΔG always positive?

A 
ΔH= +
ΔS= -
28
Q

What is a catabolic reaction?

A

High energy compounds to simple molecules

29
Q

What is a anabolic reaction?

A

Simple subunits to complex molecules.

30
Q

What does coupling of a reaction in metabolism allow to happen?

A

Reactions to occur in 2/3 steps which are SPONTAINEOUS instead of in one step which requires energy.

31
Q

When the entropy value of a reaction is positive what does this mean?

A

Increase in entropy of the system.

32
Q

When entropy is a negative value what does this mean?

A

Decrease in entropy of the system.

semester 2 chemistry revisions (12 decks)

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