rate, equilibrium and yield

Question 1

collision theory

Answer 1

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

Question 2

maxwell boltzmann distribution

Answer 2

• 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.

Question 3

activation energy

Answer 3

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

Question 4

rate of reaction

Answer 4

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

Question 5

factors affecting ROR

Answer 5

• SA, temp, concentration, pressure of gases, catalyst

Question 6

how does SA influence ROR

Answer 6

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

Question 7

how does conc. influence ROR?

Answer 7

increasing concentration, increase successful collisions will increase ROR

Question 8

how does pressure affect ROR?

Answer 8

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

Question 9

catalysts influencing ROR

Answer 9

-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

Question 10

effect of temp on ROR

Answer 10

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

Question 11

ways to measure ROR

Answer 11

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

Question 12

extent of reaction

Answer 12

how far a chemical reaction proceeds

Question 13

type of catalysts

Answer 13

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

Question 14

equilibria - a closed system

Answer 14

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

Question 15

key factors of equilibrium

Answer 15

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

Question 16

equilibrium law expression

Answer 16

K= (C)c x (D)d
—————
(A)a x (B)b

Question 17

what is K a measure of

Answer 17

the extent of a reaction ,not ROR

Question 18

what influences equilibrium constant (K)

Answer 18

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

Question 19

equilibrium constant - extent of reaction

Answer 19

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

Question 20

temperature and K

Answer 20

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

Question 21

If K is less than Q

Answer 21

reaction shifts left

Question 22

If K is greater than Q

Answer 22

reaction will shift right

Question 23

If K is equal to Q

Answer 23

no shift in equilibrium

Question 24

tackling equilibrium question - layout

Answer 24

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

Question 25

le chatelier's principle

Answer 25

IF AN EQUILIBRIUM SYSTEM IS SUBJECTED TO A CHANGE, THEN THE SYSTEM WILL SHIFT IN A DIRECTION THAT PARTIALLY OPPOSES THAT CHANGE

Question 26

changes an equilibrium system may be subjected to include:

Answer 26

- 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)

Question 27

catalyst effect on equilibrium

Answer 27

- NO EFFECT b/c catalyst will affect the forward and back reaction equally

Question 28

adding an inert gas - effect on equilibrium

Answer 28

NO EFFECT - gas is unreactive so takes no part in the reaction

Question 29

change to equilibrium - addition of reactant

Answer 29

- formation of more products - a net forward reaction - equilibrium shifts right

Question 30

change to equilibrium - adding a product

Answer 30

- formation of more reactants - net reverse reaction - equilibrium will shift to left

Question 31

change to equilibrium - remove product

Answer 31

- form more products - net forward reaction - equilibrium shifts right

Question 32

effect of changing temp on equilibrium

Answer 32

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

Question 33

effect of changing pressure on equilibrium

Answer 33

decrease pressure = favour fewer gas moles increase pressure = favours more gas moles

Question 34

what is the haber process

Answer 34

industrial manufacturing of NH3 from H and N

Question 35

conditions of haber process

Answer 35

200 atm , 400-450 celcius and iron catalyst

Question 36

% yield equation

Answer 36

actual yield / theoretical yield x 100

Question 37

how to increase yield for haber process

Answer 37

decrease temp, increase pressure , excess of reactant or removal of a product in order to favour the forward reaction

Question 38

health and safety considerations - haber process

Answer 38

pressurised system , dangerous if inhaled , toxic and corrosive

Question 39

what to do when Kc is reversed

Answer 39

use the reciprical

Question 40

what to do when Kc is halved

Answer 40

square root

Question 41

effect of dilution on equilibrium

Answer 41

conc decrease for all particles, favour reaction that will produce the most mol.

Question 42

on graph why does the curve never return to same point

Answer 42

SYSTEM CAN ONLY PARTIALLY OPPOSE CHANGE

Question 43

CO poisoning

Answer 43

instead of oxygen binding to haemoglobin the carbon monoxide binds - problem because CO has much higher K value and affinity to bind with Hb4

Question 44

how to combat CO poisoning

Answer 44

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

Question 45

how can Kc be high at a temp but ROR is low

Answer 45

Kc does not indicate ROR

Question 46

limiting reagant

Answer 46

can cause a reaction to cease - decrease ROR

Question 47

faradays 1st law

Answer 47

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

Question 48

faradays 2nd law

Answer 48

- 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