CI

Question 1

dynamic equilibrium

Answer 1

rate of the forwards reaction is equal to the rate of the backwards reaction. the reaction is still going despite the concentration being constant. only occurs in closed systems.

Question 2

what affects the value of kc and what doesn’t affect the value of kc

Answer 2

temperature affects value of kc. concentration and addition of catalysts do not affect value of kc

Question 3

advantages and disadvantages of chemical production

Answer 3

+ can be used for pharmaceutical purposes and save lives
+ dyes and cleaning products have improved our living environment and lifestyle
- some chemicals are harmful to environment
- some chemicals are extremely hazardous - eg flammable and explosive

Question 4

when calculating kc using unknown concentrations what acronym can you use

Answer 4

I - initial no. of moles
C - change in moles
E - equilibrium moles
. remember that when calculating initial moles the products all have 0 moles

Question 5

explain nitrogens diatomic molecule

Answer 5

.nitrogen forms a covalent triple bond to form a diatomic molecule
. the triple covalent bond is very difficult to break so nitrogen exists as an unreactive gas at room temperature and pressure

Question 6

how can you measure rate of reaction using titration

Answer 6

can monitor the change in concentration of a reactant or product by taking small samples at regular time intervals and titrating them

Question 7

colorimetry

Answer 7

1. use solutions containing known concentrations on colorimeter
2. use the data to create a calibration curve
3. then use a colorimeter on solution containing unknown concentration and compare the data to calibration curve via extrapolation.

Question 8

clock experiments

Answer 8

time how long it takes for reaction to occur

Question 9

assumptions made from clock reactions

Answer 9

1. temperature remains constant throughout experiment
2. concentration of reactants doesn’t change significantly during the reaction
3. reaction hasn’t preceded too far when we see the end point

Question 10

initial rate and how is it found

Answer 10

.rate of reaction at the start of a reaction
.found by timing how long it takes for a specific amount of product to form at the start of a reaction

Question 11

zero order

Answer 11

changes in concentration has no effect on rate

Question 12

first order

Answer 12

changes in concentration has a proportional change on rate

Question 13

second order

Answer 13

changes in concentration has a squared proportional change on rate

Question 14

half life

Answer 14

the time taken for half of the reactant to be used up

Question 15

arhennius equation

Answer 15

K = Ae^(-Ea /RT)

Question 16

arrhenius equation put into ln form

Answer 16

lnk = lnA - Ea/ RT

Question 17

when plotting an arrhenius equation graph, what are the axis?

Answer 17

lnk = y axis
1/T = x axis. as the numbers are small, you typically put a (x10^-3)

Question 18

what does the gradient of an arrhenius equation graph tell you

Answer 18

-Ea / R

Question 19

rate determining step

Answer 19

the slowest step in a multi step reaction. if you want to reduce rate of reaction, you try and reduce the time taken on the rate determining step