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Hrs. Chemistry > equilibrium + acids/bases > Flashcards

equilibrium + acids/bases Flashcards

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1
Q

chemical kinetics

A

the study of reaction rates

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2
Q

collision theory

A

for a reaction to occur, substance particles must physically collide in space

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3
Q

effective collisions

A
  • a collision must be effective for a rxn to occur
  • the molecules must collide in the correct orientation, and with sufficient energy
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4
Q

activation energy

A

the minimum energy required for a reaction to occur

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5
Q

transition state

A
  • when bonds are broken, produces an unstable, temporary molecule
    “activated complex”
  • as rxn continues, will settle into product
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6
Q

catalyst

A

a substance that reduces the activation energy of a reaction by changing reaction pathway without being consumed so that the transition state is different and lower in energy

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7
Q

rate of reaction

A

how fast a reaction progresses & proportional to the number of effective collisions per second

increase reaction rate by:
-more reactant surface area
-higher temperature
-a catalyst
-increasing concentration

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8
Q

surface area (rxn rate)

A

more surface area btw reactants=more collisions=more effective collisions=higher rxn rate

dissolving into solutions gets maxium surface area (liquids & gases)

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9
Q

temperature (rxn rate)

A

increase in temperature means an increase in kinetic E of the reactants=more reactants able to overcome the activtion E=higher rxn rate

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10
Q

concentration (rxn rate)

A

higher concentration of reactants=more collisions=more effective collisions=higher rxn rate

as a rxn progresses, reactants turn to products so concentration drops & rxn rate slows over time

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11
Q

pressure for gaseous systems (rxn rate)

A

increase in pressure=more particle-wall collisions=more particle-particle collisions=more effective collisions=higher rxn rate

as a rxn progresses, reactants turn to products so reactant pressure drops & rxn rate slows over time

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12
Q

catalyst (rxn rate)

A

adding a catalyst lowers the activation energy so more particles can overcome the activation barrier, and increases rxn rate

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13
Q

activation energy & rxn rates

A

higher activation energy (less collisions with enough energy to overcome the barrier) means slower rate & vice versa

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14
Q

reversible reactions

A

when the energies of the reactants & products are similar, no matter the amount of activation E, the rxn rates are similar & the reaction is reversible

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15
Q

irreversible reactions

A

if the energies of the reactants & products are different, the activation E of one will be a lot larger & the reaction will be irreversible

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16
Q

reaction rates in action

A
  • forward reaction rates are higher when there’s more reactants
  • reverse reaction rates are higher when there’s more product
  • as one dwindles the other will become more of
  • rates (not necessarily concentration of matter) will become equal at equilibrium
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17
Q

chemical equilibrium

A

when the rate of the forward reaction & the rate of the reverse direction are equal (not zero); reactants and products are still doing their reactions it’s just that there’s no net change

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18
Q

closed systems

A

to reach equilibrium, reactions must take place in a closed system where no matter can be exchanged with its surroundings (energy is fine)

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19
Q

Keq

A

a state of equlibrium: a ratio of products to reactants once a stable equilibrium is reached (@ a standard temperature)

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20
Q

Kc

A

a molarity Keq; pure solids & liquids not included, only for gaseous & aqeous reactions

the concentration of products raised to the power of their coefficients over the concentration of reactants raised to the power of their coefficients

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21
Q

Kp

A

only for gaseous reactions, a partial pressure Keq

the partial pressure of products raised to the power of their coefficients over the partial pressure of reactants raised to the power of their coefficients

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22
Q

temperature dependance

A

an equilibrium constant is specific for a certain temperature as the ratio of reactants and products change when temperature fluctuates

23
Q

reaction quotient

A

Q is the ratio of reactant to product concentration at any other time but equlibrium (basically Kc but not at equlibrium)

24
Q

Q<K

A

reaction goes to the right, and more product is created

25
Q

Q>K

A

reaction goes to the left, and more reactant is created

26
Q

Q=K

A

reactant is at equilibrium, and nothing will change

27
Q

Q or Keq in the reverse direction

A

Q or Keq in the reverse direction is the inverse of it in the forward direction

28
Q

equilibrium calculations

A

use an ICE chart to calculate concentrations at equilbirum when given inital amounts of reactant or products

29
Q

equilibrium approximations

A

when the equilibrium constant is very small, we can approximate
[initial] - x ≈ [initial]
approximation can be made when there are at least four orders of magnitude between the equilibrium constant & initial concentration

30
Q

arrhenius acids&bases

A

arrhenius acids produce H+ ions (H3O+) when dissolved in water

arrhenius bases produce OH- ions when dissolved in water

31
Q

le chatelier’s principle

A

when a chemical system at equilibrium is disturbed, the system shifts in a direction that minimizes the disturbance (in order to return to an equilibrium state)

32
Q

changing concentration

A

adding more of an aqueous or gas reactant or product shifts the equilibrium away from that species to use enough –> equilibrium
- add more product, Q increases
- add more reactant, Q decreases

33
Q

adding pure solids/liquids to equilibrium

A

no effect: pure solids & liquids are not included in the equilibrium constant

34
Q

exothermic direction

A

direction that goes from higher energy to lower energy: produces heat

35
Q

endothermic reaction

A

direction that goes from lower energy products to higher: requires heat

36
Q

changing temperature

A

increasing the temperature will shift the reaction such that it absorbs heat (towards endothermic direction)

decreasing the temperature will shift the reaction such that it produces heat (towards exothermic direction)

37
Q

changing pressure: volume

A

changing the volume will change not only total but also partial pressures:

increasing volume decreases partial pressures & the reaction will shift to the side with more moles of gas, helping to offset the overall pressure decrease (resisting a vacuum)

decreasing volume increases partial pressures & the reaction will shift to the side with fewer moles of gas, helping to offset the overall pressure increase

38
Q

changing pressure: adding inert gas

A

inert gas: noble gas

adding an inert gas increases the overall pressure of the system, but not the partial pressures –> no change in equilibrium

39
Q

adding a catalyst

A

no change to equilibrium: increases rxn rate of both directions

40
Q

bronsted-lowry definitions

A

-a Brønsted-Lowry acid is a proton donor
-a Brønsted-Lowry base is a proton acceptor

-acid/base reactions are therefore a proton transfer, by definition, from an acid to a base

41
Q

autoionization of water

A

water molecules constantly self dissociate, with one water molecule being the bronsted-lowry base and the other the acid

the specific equilibrium constant for this is Kw

42
Q

Kw

A

[H30+][OH-] = 1x10^-14

in a neutral solution, the concentration of the 2 must be equal –> each is 1x10^-7M

as one increases, the other must decrease

43
Q

hydrolysis in acids/bases

A

hydrolysis in acid: water acts as a base & accepts the proton
HA(aq) + H2O(l) ⇋ H3O+(aq) + A-(aq)

hydrolysis in base: water acts as an acid & donates a proton
B(aq) + H2O(l) ⇋ BH+(aq) + OH-(aq)

44
Q

acidic vs. basic solutions

A
  • if H30 ion concentration is > 1x10^-7 M, acidic
  • if H30 ion concentration is < 1x10^-7, basic
45
Q

pH & pOH

A

pH = -log10 [H30]; [H30]=10^-pH
pOH = -log10 [OH]; [OH]=10^-pOH

-logKw = pH + pOH = 14

46
Q

strong acids

A

HCl, HBr, HI, HClO3, HClO4, HNO3, H2SO4

any of above + H20 – H3O + conjugate base
for weak acids, reaction is reversible & in equilibrium

47
Q

strong bases

A

group 1/2 hydroxides

MOH + H20 – conjugate acid + OH
for weak bases, reaction is reversible & in equlibrium

48
Q

Ka

A

the Kc for weak acids

HA + H2O – A- + H3O+

the larger Ka is, the stronger the acid is/more it dissociates

49
Q

pKa

A

is just -log(10) Ka

50
Q

neutralization reaction

A

a reaction between acids and bases forming water and a salt (ionic compound)

If the base does not contain hydroxide (weak base), water will not be a product
HCl(aq) + NaOH(aq) → H2O(l) + NaCl(aq)

51
Q

equivalence point

A

(in a neutralization rxn) a point where moles of the acid=moles of the base

52
Q

strong acid/strong base

A

irreversible, find pH from [excess reagent]

if both H3O & OH are at the equivalence point, they will both be consumed & reactoin will be netural

pH can be determined from the concentration of excess reagent

53
Q

weak acid/strong base

strong acid/weak base

A

it will go to completion, if the excess is weak, then find the concentration using Keq; if the excess is strong, ah fuck it alllll

Hrs. Chemistry (8 decks)

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