chemical reactions

Question 1

physical vs chemical change

Answer 1

• physical is like shape change. chemical ga the chemical properties change (burning)

Question 2

effect of conc (l) + pressure (g) on r.o.r

Answer 2

increase = more particles per unit volume = more frequent collisions = more successful

Question 3

effect of surface area (s) on r.o.r

Answer 3

increase = more particles available to react = more frequent collisions = more successful

Question 4

effect of temp on r.o.r

Answer 4

increase = more k.e = more with energy > activation energy = more frequent collisions

Question 5

effect of catalyst on r.o.r

Answer 5

increase = lowers activation energy = more with energy > a.e = more collision

Question 6

catalyst

Answer 6

increases r.o.r + is unchanged at end (pathway graph ga a.e is lower)

Question 7

investigating r.o.r

Answer 7

• mass change
• gas forming (gas syringe)

Question 8

r.o.r graph

Answer 8

steeper at first + horizontal sooner + same product

Question 9

example of reversible

Answer 9

• heat hydrated
• add water to anhydrous
  (CoCl2·6H2O) (CuSO₄·5H₂O)

Question 10

equilibrium when

Answer 10

• rate of forward reaction = backward
• conc. of reactants + products no longer changing

Question 11

effect of temp on equilibrium

Answer 11

• i.t.e.n
• d.t.e.x

Question 12

effect of pressure on equilibrium

Answer 12

increase favours side with less gas moles

Question 13

effect of conc. on equilibrium

Answer 13

increase favours reaction which reduces

Question 14

effect of catalyst on equilibrium

Answer 14

no effect

Question 15

haber materials

Answer 15

• hydrogen from methane
• nitrogen from air
  N2 + 3H2 ⇌ 2NH3

Question 16

haber conditions

Answer 16

iron catalyst + 20 000 kPa/200 atm + 450°C

Question 17

contact materials

Answer 17

• SO2 from burning sulfur/roasting sulfide
  ores
• oxygen from air
  2SO2 + O2 ⇌ 2SO3

Question 18

SO2 ⇌ SO3 conditions

Answer 18

vanadium (V) oxide catalyst + 200 kPa/2 atm + 450°C

Question 19

why haber conditions

Answer 19

• high pressure is dangerous + costly engineering
• low temp is slow rate
• so high temp + catalyst
• more economic to get low yield fast rate

Question 20

redox

Answer 20

reactions involving simultaneous oxidation and reduction (gain + loss of e-)

Question 21

oxidation

Answer 21

gain of O2 / loss of e- / increase oxi. no.

Question 22

reduction

Answer 22

loss of O2 / gain of e- / decrease oxi. no.

Question 23

sum of oxis

Answer 23

0

Question 24

acidified potassium manganate (VII)

Answer 24

oxidising agent + test for reducing agent
- purple to colourless

Question 25

aqueous potassium iodide

Answer 25

reducing agent + test for oxidising agent - colourless to brown

Question 26

oxidising agent

Answer 26

oxidises another substance and is itself reduced

Question 27

reducing agent

Answer 27

reduces another substance and is itself oxidises