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SCH4UN > equilibrium terminology > Flashcards

equilibrium terminology Flashcards

1
Q

what is a chemical equilibrium

A

the state of a reaction in which all products and reactants have reached constant concentrations in a closed system

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2
Q

how does ocean acidification relate to chemical equilibriums?

A
  • ocean acidification is driven by the absorption of carbon dioxide (CO2) into seawater, leading to chemical equilibria involving the conversion of CO2 to carbonic acid, bicarbonate ions, and carbonate ions.

-more hydrogen ions lowers pH (acidic), which poses a threat to marine life

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3
Q

what is a dynamic equilibrium

A
  • a state of balance btw continuing processes
  • rates of the forward and reverse reactions at the same time are occurring at the same rate
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4
Q

what is a volatile liquid?

A

A volatile liquid is a substance that has a high tendency to vaporize or evaporate at relatively low temperatures.

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5
Q

what happens if a volatile liquid in an open container underneath an enclosed space

A

the liquid will evaporate until the air in the closed container is saturated with particles of the vapour

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6
Q

what happens when the rate of condensation is equal to the rate of evaporation

A

the system is in a state of dynamic equilibrium since both events occur simultaneously

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7
Q

what is equilibrium position

A

the point where the relative concentrations of the reactants and products stop changing

  • the position will either favour the reactants or products
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8
Q

what is a reversible reaction

A

a chemical reaction that proceeds both the forward and reverse directions, setting up an equilibrium in a closed system

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9
Q

does the direction matter for when equilibrium is reached

A

no, the same equilibrium concentrations are related regardless

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10
Q

What does K represent

A

Equilibrium constant (AT EQUILIBRIUM)

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11
Q

What is K dependent on

A

temperature

  • In general, an increase in temperature favors an endothermic reaction (absorbs heat), shifting the equilibrium towards the side of the reaction with a higher number of moles, while a decrease in temperature favors an exothermic reaction (releases heat), shifting the equilibrium towards the side with fewer moles.
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12
Q

what is homogeneous equilibria

A

involve the same phase, (all gases for ex.)

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13
Q

what is heterogeneous equilibria

A

involve more than one phase (l,g,g for ex.)

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14
Q

What does heterogeneous equilibria depend on?

A
  • doesn’t depend on the amount of the pure solids or liquids present
  • if pure solids/liquids are present, they aren’t represented in K calcs
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15
Q

If K is smaller than 1

If K is bigger than 1

If K is equal to 1

A

smaller than 1: reactants are greater than products
- favours the reactants, reverse, towards the left

bigger than 1: products are greater than reactants
- favours the products, forward, towards the right

equal to 1: products=reactants

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16
Q

Le Chatelier’s Principle

A
  • a system will readjust to reduce the disturbance and regain equilibrium
    (the way a system will react to offset a disturbance)
  • if we disturb a reaction at equilibrium, we can regain more product
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17
Q

If more reactants are added to a system

A
  • the forward reaction will move faster, using up A and B faster than C and D can be replaced
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18
Q

the amount the equilibrium increases/decreases by depends on

A

the coefficient/number of moles of the reactant/product

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19
Q

example of temperature affecting K:

  • Brown reactant to colourless product is upset by temperature which makes it darker brown, therefore is it endo/exo thermic?
A

endothermic, if heat is being added to produce a darker brown colour then its producing more product, in the reverse reaction

  • favouring formation of products, shift towards the left
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20
Q

increasing temperature is just like

A

adding heat

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21
Q

what happens to an equilibrium when its cooled?

A

the equilibrium shifts to the side with the heat as the equilibrium responds to the disturbance by replacing the heat that has been removed

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22
Q

brown reactant to colourless product
- plunged in ice water

A
  • removal of heat
  • exothermic (bc adding heat makes it darker brown which is the reactant)
  • product decreases, reactant increases
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23
Q

temperature is increased graph

A

IF ENDOTHERMIC
reactants: increased
products: decreased

IF EXOTHERMIC
reactants: decreased
products: increased

24
Q

how do changes in the volume affect the equilibrium

A
  • decrease in volume (increase in pressure) it shifts in a direction which decreases the total number of molecules
  • less space reduces the number of molecules present
  • if volume is doubled, reactants will increase and products will decrease

when volume decreases it favours the side with fewer moles & vice versa

25
Q

what is the haber process?
how is it related to le chatelier’s principle and what is its importance?

A
  • method for synthesizing ammonia (NH3) from nitrogen (N2) and hydrogen (H2) gases, typically carried out at high pressures and temperatures with the aid of an iron catalyst
  • as it would normally (just disturbances) for ex. increasing the pressure, which is one of the factors affecting the equilibrium, can shift the reaction toward the side with fewer moles of gas, favoring the formation of ammonia
26
Q

how does adding a catalyst affect le chateliers principle?

A
  • doesn’t affect K, or shift the position of the equilibrium
  • system will reach equilibrium sooner (increases the rate of the reaction by decreasing the activation energy)
  • Catalyst lowers the activation energy for both forward and reverse reactions
27
Q

why doesn’t adding a catalyst affect K/shift the position of the equilibrium?

A
  • because a catalyst speeds up the rate of both the forward and reverse reactions equally, allowing the system to reach equilibrium faster but not altering the final concentrations of reactants and products.
  • A catalyst provides an alternative reaction pathway, reducing the activation energy without changing the thermodynamics of the equilibrium.
28
Q

what is an inert gas?

A

An inert gas is a chemically non-reactive substance, often a noble gas or nitrogen, that does not readily undergo chemical reactions under normal conditions.

29
Q

how does adding an inert gas affect le chateliers principle?

A

equally decrease the probability of substances colliding for the reactant and product molecules

  • doesn’t affect the system
30
Q

why doesn’t adding an inert gas affect le chateliers principle?

A
  • increases total pressure but doesn’t affect partial pressures
  • doesn’t react with substances, so it doesn’t change the ratio of reactants to products and doesn’t thus cause a shift
31
Q

SUMMARY: LE CHATELIERS PRINCIPLE

A

Concentration:
- shifts equilibrium
- DOESN’T change equilibrium constant

Pressure:
- shifts equilibrium
- DOESN’T change equilibrium constant

Volume
- shifts equilibrium
- DOESN’T change equilibrium constant

Temperature
- shifts equilibrium
- CHANGES equilibrium constant

Catalyst:
- doesn’t shift equilibrium
- DOESN’T change the equilibrium constant

*dependent on relative moles

32
Q

what variables affect chemical equilibria

A

concentration, temperature, and volume

33
Q

what variables don’t affect chemical equilibria

A

catalysts and inert gases

34
Q

what is solubility

A

amount of solute that dissolves in a given amount of solvent at a certain temperature and pressure

35
Q

solubility product constant: Ksp

A
  • eq constant for the eq between an insoluble or slightly soluble iconic compound and its sat solution
  • higher Ksp substance, increased solubility
36
Q

what is the common ion effect

A

concentration of a certain ion can be increased through the addition of a certain compound
- adding the common ion can decrease solubility (there will be a shift to the left)

37
Q

trial ion product, Qsp

A
  • determine the concentrations provided are high enough for precipitation to occur
  • concentration values aren’t necessarily at equilibrium, non equilibrium concentrations are used
38
Q

Comparing Qsp to Ksp

A

Q is greater than K: more ions in solution than required: precipitate (LEFT SHIFT) TOO MUCH PRODUCT

Q is less than K: ions are able to remain in solution: unsaturated (RIGHT SHIFT) TOO MUCH REACTANT

Q is equal to K: then the solution is unable to dissolve more ions: saturated, at equilibrium

39
Q

what are THE strong acids

A

HCl, HBr, HI, HNO3, HClO4, H2SO4

40
Q

what are strong acids

A
  • mostly ionize in water/aq solution to produce hydrogen ions
  • HA = H+ + A-
41
Q

pH scale

A
  • Hydrogen ion concentration is expressed in terms of pH
  • change in one unit of pH changes the concentration by ten
42
Q

what are strong bases

A
  • fully ionize in water/aq solution to produce hydroxide ions
43
Q

what are the strong bases

A

OH with group 1 and 2 metals (with barium) (magnesium is an exception)

44
Q

Kw value

A

1.0x10^-14

45
Q

Arrhenius acid and base theory vs Bronsted Lowry theory

A

Arrhenius:
- when acids dissolve in water: hydrogen ion concentration increases
- when bases dissolve in water: hydroxide ion concentration increases

Bronsted Lowry
- acids are proton donators
- bases are proton acceptors

46
Q

issues with Arrhenius acid theory

A
  • ammonia and sodium bicarbonate are basic substances but lack OH-
  • it can only describe acid-base chemistry in aqueous solutions (dissolving in water)
47
Q

issues with bronsted Lowry theory

A
  • some acids don’t have a proton present for ex. BF3
48
Q

conjugate bases and acids

A
  • the stronger the acid, the weaker the conjugate base and vice versa
  • the more readily a substance gives up a proton, the less likely its conjugate gives up a proton and vice versa
49
Q

what are strong electrolytes

A

a substance that dissolves to produce exclusively ions, 100% ionization or disassociation

50
Q

what are weak electrolytes

A

a substance that dissolves to produce limited ions
1% ionization of disassociation, reversible

51
Q

what are polyproptic acids

A
  • acids involving more than one hydrogen
  • ionization of hydrogen occurs in more than one step
  • when calculating pH, only use the first reaction in an ionization sequence (bc percent of hydrogen is so small in second step)
52
Q

what are buffers

A

solution that can resist pH change upon the addition of an acidic or basic components. It is able to neutralize small amounts of added acid or base, thus maintaining the pH of the solution relatively stable.

53
Q

100s rule

A

ratio between the greatest initial concentration and value of K must be greater than 100, for the x value to be inadmissible (value-x, x value ignored)
- error must be less than 5%

54
Q

le chatelier’s principle alongside the removal and addition of product

A

If we add product, equilibrium goes left, away from the product. If we remove product, equilibrium goes right, making product. If we remove reactant, equilibrium goes left, making reactant.

55
Q

precipitate forms when…

A

Q is larger than K, product concentration is larger than what’s needed which can result in formation of precipitate

56
Q

amphoteric vs Amphitropic

A

Amphoteric
- can act as both an acid and a base

Amphiprotic susbtances
- both donate and accept protons

SCH4UN (9 decks)

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