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chemistry 3/4 > rate, equilibrium and yield > Flashcards

rate, equilibrium and yield Flashcards

1
Q

collision theory

A

particles must collide with correct orientation and sufficient energy in order to disrupt bonds in the molecule –> form a successful collision

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2
Q

maxwell boltzmann distribution

A
  • demonstrates a range of energies of particles (kinetic)
    -area under the curve is equal to the total number of particles in the sample
  • for reaction the particles must have enoigh energy to overcome activation energy.
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3
Q

activation energy

A
  • Ea is minimum amount of energy required to generate a reaction
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4
Q

rate of reaction

A
  • the speed at which a reaction occurs
  • ror is measured by change in concentration of a reactant or product per unit time
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5
Q

factors affecting ROR

A
  • SA, temp, concentration, pressure of gases, catalyst
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6
Q

how does SA influence ROR

A
  • increasing the SA, increase frequency of fruitful / successful collisions bw particles will increase ROR
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7
Q

how does conc. influence ROR?

A

increasing concentration, increase successful collisions will increase ROR

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8
Q

how does pressure affect ROR?

A

increase frequency of successful collisions per unit time - done by decreasing the volumw of a container/vessel b/c decrease space for particles to collide

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9
Q

catalysts influencing ROR

A

-provides an alternate pathway by lowering activation energy for a particular reaction
- particles on the surface distort and disrupt the bonds w/in molecules hence lowers Ea required for reaction-> greater proportion of particles w energy greater than Ea and successful collisions - increase ROR

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10
Q

effect of temp on ROR

A

-increase proportion of particles with sufficient energy for a reaction - increase proportion of successful collisions

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11
Q

ways to measure ROR

A

to determine how fast a reaction occurs:
- measure rate of gas production
- measure change in mass
- for reaction w acids and bases - measure change in pH over time
- if produces a precipitate then measure time it takes for solution to become cloudy

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12
Q

extent of reaction

A

how far a chemical reaction proceeds

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13
Q

type of catalysts

A
  • homogenous - same state as reactant+ product
    -heterogenous - different state to reactants + products
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14
Q

equilibria - a closed system

A

-when forward and back reactions OCCUR at the same rate the reaction is at equilibrium
- occur in reversible reaction

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15
Q

key factors of equilibrium

A
  • amount (mol and mass) of chemical substances are constant
  • conc. of chem. substances are constant
    -total gas pressure is constant
    -temperature is constant
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16
Q

equilibrium law expression

A

K= (C)c x (D)d
—————
(A)a x (B)b

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17
Q

what is K a measure of

A

the extent of a reaction ,not ROR

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18
Q

what influences equilibrium constant (K)

A
  • changes with temp
  • not depend on initial conc. of substances
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19
Q

equilibrium constant - extent of reaction

A

. bw 10^-4 and 10^4 = significant
. > 10^4 = almost complete
. <10^-4 = negligible reaction

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20
Q

temperature and K

A

exothermic - temp. increase - K decreases
endothermic - temp increase - K increases

21
Q

If K is less than Q

A

reaction shifts left

22
Q

If K is greater than Q

A

reaction will shift right

23
Q

If K is equal to Q

A

no shift in equilibrium

24
Q

tackling equilibrium question - layout

A

I - intital
C - change
E - equilibrium
F - final conc

25
le chatelier's principle
IF AN EQUILIBRIUM SYSTEM IS SUBJECTED TO A CHANGE, THEN THE SYSTEM WILL SHIFT IN A DIRECTION THAT PARTIALLY OPPOSES THAT CHANGE
26
changes an equilibrium system may be subjected to include:
- A change in temperature (shift depends upon the reaction being endothermic /exothermic) -Adding a catalyst (nochange) -Adding an inert gas (no change) -Addition of a reactant or removal of product (will favour forward reaction) -Removal of a reactant or addition of a product (will favour back reaction) -A change in pressure -Dilution(solutions)
27
catalyst effect on equilibrium
- NO EFFECT b/c catalyst will affect the forward and back reaction equally
28
adding an inert gas - effect on equilibrium
NO EFFECT - gas is unreactive so takes no part in the reaction
29
change to equilibrium - addition of reactant
- formation of more products - a net forward reaction - equilibrium shifts right
30
change to equilibrium - adding a product
- formation of more reactants - net reverse reaction - equilibrium will shift to left
31
change to equilibrium - remove product
- form more products - net forward reaction - equilibrium shifts right
32
effect of changing temp on equilibrium
increase temp = favour endothermic reaction, where enthalpy change = POS bc system wants to reduce temperature decrease temp = favour exothermic reaction, where enthalpy change = NEG bc system wants to increase temp
33
effect of changing pressure on equilibrium
decrease pressure = favour fewer gas moles increase pressure = favours more gas moles
34
what is the haber process
industrial manufacturing of NH3 from H and N
35
conditions of haber process
200 atm , 400-450 celcius and iron catalyst
36
% yield equation
actual yield / theoretical yield x 100
37
how to increase yield for haber process
decrease temp, increase pressure , excess of reactant or removal of a product in order to favour the forward reaction
38
health and safety considerations - haber process
pressurised system , dangerous if inhaled , toxic and corrosive
39
what to do when Kc is reversed
use the reciprical
40
what to do when Kc is halved
square root
41
effect of dilution on equilibrium
conc decrease for all particles, favour reaction that will produce the most mol.
42
on graph why does the curve never return to same point
SYSTEM CAN ONLY PARTIALLY OPPOSE CHANGE
43
CO poisoning
instead of oxygen binding to haemoglobin the carbon monoxide binds - problem because CO has much higher K value and affinity to bind with Hb4
44
how to combat CO poisoning
must significantly increase conc of O2 to encourage Hb4 and O2 to react which will then cause back reaction of Hb4CO4 to attempt to increase Hb4 in system which then increase Hb4 to bind with O2
45
how can Kc be high at a temp but ROR is low
Kc does not indicate ROR
46
limiting reagant
can cause a reaction to cease - decrease ROR
47
faradays 1st law
the amount of any substance discharged at an electrode during electrolysis is directly proportional to the quantity of electric charge passed through - linear - mass gained at cathode= mass lost at anode
48
faradays 2nd law
- the amount in mol. of any substance discharged at an electrode during electrolysis is the reciprocal of the charge of the charge on the ion - greater charge on the ion then greater electrical charge to discharge ion

chemistry 3/4 (8 decks)

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