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chemical equilibrium Flashcards

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1
Q

what reactions are we looking at?

A
  • reversible reactions
  • never fully complete because of dynamic nature
  • called equilibrium chemical reactions
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2
Q

what do equilibrium chemical reactions entail?

A
  • two reactions (forward and back) occurring at the same time
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3
Q

what is equilibrium?

A

the rate of the reactions thus if a reaction system is at equilibrium, the rate of both reactions is equal

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4
Q

what is the equilibrium constant and what is its unit?

A

Kc

M

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5
Q

what is Kc?

A

a study of yield

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6
Q

what is the equation of the equilibrium constant?

A

[product]/[reactant]

coefficients are represented as powers

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7
Q

what does a large and small Kc represent?

A
  • large: large [products]

- low: low [products]

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8
Q

what value must Kc be to be at =m?

A

between 10^-4 and 10^4

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9
Q

Kc bigger than 10^4?

A

favours a forward reaction, large yield

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10
Q

Kc smaller than 10^-4

A

favours a backwards reaction, low yield

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11
Q

how do you find M?

A

use index laws within the fraction to solve

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12
Q

how do you calculate concentration?

A

c = n/V

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13
Q

how do you solve the concentration of a chemical;?

A

sub and rearrange

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14
Q

what is the RICE method?

A
  • write out ratios of stoich
  • write out initial mol from question (some might be 0 if not specified)
  • use on to see how much change there is in mol at =m
  • use that mole amount and divide accordingly to match stocih and use that to subtract from initial amounts
  • calculate cocentration from =m mol
  • use that to calculate Kc
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15
Q

double stoichiometry?

A

square Kc

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16
Q

halve stoichiometry?

A

square root Kc

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17
Q

reverse reaction?

A

inverse Kc

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18
Q

what are the two classifications of equilibrium systems?

A

open system: matter and energy can interact with surroundings eg. bushfire
closed system: matter and energy are only exchanged within the system. eg. submarines

19
Q

does exo or endo affect =M?

A

yes, in a closed system

20
Q

how can energy be written in reactions? exo? endo?

A

as product in exo and a reactant in endo

21
Q

what conditions change Kc?

A

temperature only

22
Q

what is the definition of LCP?

A

if a system is subjected to a change, the =m system adjusts itself to partially oppose the change, re-establishing the =m.

23
Q

how is LCP used in industry?

A

changes are Mae to increase yield (amount of reactant made into product)

24
Q

how is LCP used in physiological perspectives?

A
  • maintaining of homeostasis (=m)
25
Q

how can =m systems be analysed?

A
  • Kc values

- experimental ‘colour’ observations

26
Q

how can concentration of reactants affect the =m in LCP?

A

addition: add a few drops, according to LCP the =m will favour a forward direction to re-establish =m
decrease: add a chemical that is involved in a side reaction with a reactant. According to LCP, a backwards reaction will occur

27
Q

how can concentration of products affect =m in LCP?

A

increase concentration: add a few drops of product. backwards

decrease: remove product. forwards

28
Q

how do you change pressure in an aqueous environment?

A
  • dilute by adding more solvent (usually h2O)

- concentrate by removing solvent (evaporate)

29
Q

how do you change pressure in a gaseous environment?

A
  • change size or volume of reaction system eg. syringe
30
Q

how does pressure affect reactions according to LCP?

A
  • increase of pressure (decrease volume) promotes a reaction towards side with fewer particles
  • decreased pressure (increased volume) promotes a reaction to the side with more particles
31
Q

how does a catalyst affect reactions LCP?

A

speeds up forward and back reaction so =m is reached in shorter time

32
Q

how does temperature affect in endo?

A

increase: increase in reactants therefore a forward reaction is promoted. This is a permanent forward reaction until the chemist decides. increases Kc
decrease: decrease of reactants. back reaction. decrease of Kc

33
Q

how does temperature affect in exo?

A

increase: back reaction, decreased Kc
decrease: forward reaction, increase Kc

34
Q

what is temperature the biggest factor in?

A

yeild

35
Q

what are LCP considerations?

A
  • Kc is only affected by temp
  • volume/pressure: if stoich of reactants and products are equal, then there will be no change. Adding an inert gas causes a change to pressure but because they are not reactive, there is no change to =m system
36
Q

what do concentration v time graphs show?

A
  • the change induced on the system

- the response of that system to oppose the change

37
Q

how does an increase of product look on a graph?

A
  • increase that substance by the stoich and then decrease it nearly to normal
  • other reactants will gradually move down in conc.
  • products will increase
  • all according to stoich
38
Q

how does volume change look on a graph?

A

a sharp increase/decrease in all reactants and products

39
Q

how does a temp change look on a graph?

A

a gradual increase/decrease

40
Q

describe competing equilibria: carbon monoxide poisoning

A

Hb + O2 Hb-O2

CO has a greater affinity for Hb (20 000 times greater) than O2 and forms Hb-CO (carboxy Haemoglobin)

symptoms:
- Hb-O2 breaks down
- no oxygen to cells
- cellular respiration stops
- death

41
Q

describe osteoporosis?

A
  • don’t get enough Ca2+ so bone dissociates
42
Q

describe ocean chemistry

A

increased carbon dioxide, produced increased ocean acidity through a series of reactions

43
Q

describe ventilation

A

hypoventilation: breathing at low rate there fore not releasing a lot of CO2
hyperventilation: breathing rate is increased therefore releasing lots of CO2

Chemistry (28 decks)

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