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Chemistry > Reaction Feasibility + Chemical Equillibrium for some reason > Flashcards

Reaction Feasibility + Chemical Equillibrium for some reason Flashcards

1
Q

What is the standard enthalpy of formation?

A

The enthalpy change when 1 mole of a substance is formed from its elements in their standard states

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2
Q

standard enthalpy equation?

A

ΔH°= ΣΔHf (products) – ΣΔHf (reactants)

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3
Q

What is entropy(S)?

A

A measure of the degree of disorder

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4
Q

What does the second law of thermodynamics state?

A

the total entropy of a reaction system and its surroundings always increases for a spontaneous reaction

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5
Q

Heat energy absorbed by the reaction system from the surroundings

A

decreases the entropy of the surroundings

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6
Q

an increase in temperature increases

A

entropy

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7
Q

What does the third law of thermodynamics state?

A

The entropy of a perfect crystal at 0K is zero

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8
Q

Gibbs equation?

A

ΔG° = ΔH° - TΔS°

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9
Q

negative ΔH°
positive ΔS°

A

ΔG° is negative, reaction is always feasible

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10
Q

positive ΔH°
negative ΔS°

A

ΔG° is positive, reaction is never feasible

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11
Q

negative ΔH°
negative ΔS°

A

Reaction is only feasible at low temperatures

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12
Q

positive ΔH°
positive ΔS°

A

Reaction is only feasible at high temperatures

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13
Q

To calculate the temperature let

A

ΔG°=0

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14
Q

K depends on the reaction

A

temperature

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15
Q

K>1 means

A

the equillibrium lies to the right (more products than reactants)

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16
Q

K<1 means

A

the equillibrium lies to the left (more reactants than products)

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17
Q

K=

A

[C][D] /[A][B] (products on the numerator, reactants on the denominator) (raise each to the number of moles)

18
Q

What is the equillibrium constant? (K)

A

characterises the equillibrium composition of the reaction mixture

19
Q

The concentrations of pure liquids and solids is

A

1

20
Q

For endothermic reactions, a rise in temperature causes an _________ in K and the yield of the product is ____________

A

increase, increased

21
Q

What does amphoterric mean?

A

can act as both an acid and a base

22
Q

pH equation?

A

pH= -log[H+]

23
Q

What is Kw?

A

dissociation constant

24
Q

Kw equation?

A

Kw=[H+][OH-]

25
Q

H+ equation?

A

[H+]=10^-pH

26
Q

How to calculate the concentration of one ion if the other ion is known?

A

use Kw or pH+pOH=14

27
Q

Bronsted-Lowry definition of an acid?

A

A proton donor

28
Q

Bronsted-Lowry definition of a base?

A

a proton acceptor

29
Q

What does Ka represent?

A

The acid dissociation constant

30
Q

pKa equation? (strong acid pH equation)

A

pKa=-logKa

31
Q

weak acid pH equation?

A

pH=1/2pKa-1/2logc

32
Q

A soluble salt of a strong acid + strong base=

A

neutral solution

33
Q

A soluble salt of a weak acid + strong base=

A

alkaline solution

34
Q

A soluble salt of a strong acid + weak base=

A

acidic solution

35
Q

What is a buffer solution?

A

one in which the pH remains approximately constant when small amounts of acid, base or water are added

36
Q

What is a buffer made up of?

A

A weak acid/base and the salt of that weak acid/base

37
Q

Describe an acid buffer solution

A

In an acid buffer solution, the weak acid provides hydrogen ions when these are removed by the addition of a small amount of base. The salt of the weak acid provides the conjugate base, which can absorb excess hydrogen ions when these are produced by the addition of a small amount of acid

38
Q

Describe a basic buffer solution

A

In a basic buffer solution the weak base removes excess hydrogen ions, and the conjugate acid provided by the salt supplies hydrogen ions when these are removed.

39
Q

pH of acid buffer solution equation

A

pH=pKa-log x [acid]/[salt]

40
Q

At 25C the value of Kw is

A

1 x 10^-14

Chemistry (11 decks)

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