As expected [from last time]:
Some suggested answers [that are not necessarily complete, coherent or right]
A Mandy &
mostly Mao collaboration [as expected]
AREA OF STUDY 1: INDUSTRIAL CHEMISTRY
Reaction Rates
1. What are the conditions that need to be met so that a reaction occurs?
must collide with the right orientation and enough energy to overcome the activation energy barrier
2. What is the collision theory?
some reactions take place because the reactant particles collide
collision based reactions can achieve higher rate of reaction by either or both having higher rate of collision or the particles having higher kinetic energy
3. What is activation energy?
energy required initially so a reaction can proceed [in uncatalysed reactions, this is the energy required to break bonds]
4. Explain in terms of collision theory how each of the following affects the rate of reaction:
a) Concentration b) Pressure c) Temperature d) Surface Area e) Catalyst
a) higher concentration of reactants = more particles to react = more frequent fruitful collisions = higher ROC
b) Higher pressure, the particles are closer together so more frequent collisions = more fruitful collisions = higher roc
c) temperature increase = particles move around faster = more collisions, particles have more kinetic energy = higher probability for fruitful collision = more fruitful collisions = higher ROC
d) increased surface area = more reactant particles exposed = more collisions = more frutiful = high roc
e) use of catalyst = provides alternative reaction pathway = activation energy lowered = higher proportion of collisions are considered successful = higher roc
5. How does the reaction rate change with respect to time if the reaction is a) exothermic b) endothermic?
Exothermic reactions release heat to surrounding - RR increase
Endothermic reactions absorb heat from surrounding - RR decrease
6. Name two ways how the rate of a reaction could be monitored.
depend on the reaction:
- evolution of products [such as gas, coloured compound, crystals]
- rate of consumption of reactant
- overall pressure/colour intensity
Equilibrium Reactions
7. What are equilibrium reactions?
dynamic reactions that goes forward as well as backward
8. When is equilibrium reached?
rate of forward reaction = rate of backward reaction, i.e. no overall change in concentration of products or reactants
9. Why is equilibrium said to be dynamic?
reaction is always taking place, i.e. at equilibrium the reactions do not "stop"
10. Given the equation A + B ↔ C + D, write the equilibrium constant for the reverse reaction.

11. Explain the effect of a catalyst on the yield of a reaction.
nothing, it allows equilibrium to be established quicker, but no effect on yield
12. What is the difference between the concentration fraction and the equilibrium constant?
K is constant for a temperature, whereas Q [or CF] is the expression at all sorts of conditions [even when not at equilibrium]
13. When the concentration is smaller than the equilibrium constant, what will be the net reaction?
net forward
14. When the concentration is larger than the equilibrium constant, what will be the net reaction?
net backward
15. What does the magnitude of K tell us about an equilibrium reaction?
larger K -- most reactants are converted to products
small K -- most reactants remain unreacted
16. How does K change with respect to time when the reaction is a) exothermic b) endothermic?
in VCELand, temperature is kept constant, hence K does not change with respect to time.
17. State Le Chatelier’s principle.
A equilibrium system will partially oppose a change done to it.
18. Using Le Chatelier’s principle, explain how each of the following affects the position of equilibrium:
a) addition of reactants or products b) changing the temperature
c) changing the pressure or volume d) dilution of system e) addition of catalysts
f) addition of inert gases g) addition of water if water is also a reactant
a) add reactants=net forward, add products = net backwards
b) change in temp, assume increase in temp, if forward reaction is exo, there is a net backwards reaction, if endo, net forwards
c) changing pressure or volume, if pressure increase, reaction that produces less particles is favoured, vice versa
d) dilution is increase in volume? net reaction towards the side that produces more particles
e) catalyst = no change
f) no change
g) net forward
19. Explain why pure water has a pH of 7. AT 25 DEGREES ONLY!
the H
+ concentration at 25 degrees is

M
20. When the temperature is increased, what is the effect on the pH of pure water?
decrease. self ionisation of water is endothermic
21. Give a typical equilibrium of a weak acid.
\leftrightharpoons H^+(aq)+A^-(aq))
K
a is small
22. Define a strong acid in terms of equilibrium.
K
a is large, i.e. most of the reactants are converted to products.
23. List the following acids from weakest to strongest: hydrofluoric acid, ethanoic acid, boric acid, nitrous acid, and lactic acid.
Boric < ethanoic < lactic < nitrous < hydrofluoric
24. Define percent ionisation.
the percentage of reactants that reacted to products [ionised] in an acid dissociation reaction.
25. What is a buffer?
a weak acid and its conjugate base [or a weak base and its conjugate acid] that can compensate for addition of base and acid to a system, hence keeping the pH roughly constant.
Waste Management
26. Define atom economy.
percentage of atoms in the reactants that end up as desired product
27. Define ‘waste management’ and
list some ways how waste can be ‘managed.’ <---can't be bothered.
Minimisation of waste [products/energy] or responsible disposal of waste.
Industrial production of a chemical
28. Give the formula and name of the chemical you have studied this year.
Sulfuric acid, H2SO4
29. Give the equilibrium reaction in the industrial production of your chemical and state whether it is exothermic or endothermic.
[tes]2SO_2(g)+2O_2(g)\leftrightharpoons 2SO_3(g)[/tex], exothermic
30. List the conditions of temperature and pressure that would theoretically maximise yield and rate of the industrial production of your chemical.
high pressure, low temperature
31. List the conditions of temperature and pressure that are actually used in the industrial production of your chemical explaining the difference, if any, between your answer to Q 30 and Q31.
450 degrees celsius [moderate temperature]
1 atm pressure
rate of reaction is improved by use of catalysts [in catalyst beds so to maximise surface area]
equilibrium yield is improved by use of excess reactants, continual removal of product and cycling [3 times through the reaction chamber]
the yield and ROR become good enough that high pressure is not necessary.
32. Write an equation where your chemical is a reactant.
\leftrightharpoons H^+ (aq) + HSO_4^-(aq))
33. Write an equation where your chemical is a product.
 + H_2O(l) \to 2H_2SO_4(l))
34. List 3 uses of your industrial chemical.
production of fertiliser
electrolyte in car batteries
production of dyes
35. Explain how the principles of green chemistry apply to the industrial production of your chemical.
the only product is the desired product. therefore ATOMIC ECONOMY TO THE MAX.
36. List two health and safety procedures that are followed in the industrial production of your chemical.
reaction chambers are sealed [as gases are toxic]
safe handling of reactants/chemicals, MSDS, responsible disposal, spillage plans,
earthquake survival plans, alien domination plans, terrorist strike plans, experiment on the chickens plan, world domination plans...37. Explain how waste management is applied to the industrial production of your chemical.
excess heat is used to power other processes/generate electricity.
AREA OF STUDY 2: SUPPLYING AND USING ENERGY
Energy Sources
38. Explain the difference between the terms ‘renewable’ energy sources and ‘sustainable’ energy sources’.
Renewable - can be reproduced within a reasonable timeframe
Sustainable - can be reproduced as an ongoing process that meets the demand of modern day society
39. List 5 renewable and 3 non-renewable energy sources.
Renewable - biochemical fuels, solar, wind, tidal, geothermal
non-renewable - fossil fuels, natural gas, nuclear
40. Which energy sources currently do not commercially operate in Australia? Give reasons for your answer.
Nuclear, due to security and waste management concerns.
Thermochemistry
41. What is an energy profile?
Change in enthalpy of a reaction
42. What is an endothermic reaction? What is an exothermic reaction?
Endothermic: net absorption of energy from surroundings
Exothermic: net release of energy to surroundings
43. Draw a typical energy profile for an exothermic and an endothermic reaction.
| _ exothermic
| / \
|__/ \
| \
| --
|____________
| _ endothermic
| / \_____
|__/
|
|
|____________
44. Define enthalpy in terms of bonding and energy.
Strong bonds - small chemical energy, low enthalpy
Weak bonds - high chemical energy, high enthalpy
45. Name three important parts of a thermochemical equation.
balanced equation, states of chemicals, coefficients,

.....?
46. Explain the difference between heat capacity and heat of combustion.
heat capacity is the energy required to raise one gram of the said material by one degree
heat of combustion is the energy released when one gram of the said material undergoes complete combustion
47. Explain why the heats of combustion of foods are given in kJ per gram rather than kJ per mol.
foods do not have a known chemical formula [it is a mixture of many different compounds], hence there is no definite molar mass.
48. Explain the function of a calorimeter.
measures the change in energy
49. Give the names of two different types of calorimeters and describe their respective uses.
Solution calorimeter - measures change in energy of reactions between aqueous/solid species.
Bomb calorimeter - measures change in energy of more energetic reactions such as combustion in a sealed clay chamber.
50. Why do calorimeters need to be calibrated?
Allow interpretation of data
51. Name three ways how a calorimeter can be calibrated.
Pass a current with known voltage for a certain amount of time
Reaction of accurate mass and

??Use of specific heat capacities??
52. Name two ways how the actual value of the calibration factor could be higher than the calculated value.
not enough water
inaccurate measurements
53. Name two ways how the actual value of the calibration factor could be lower than the calculated value.
too much water
inaccuratae measurements
54. Name three formulas used in thermochemistry.

Electrochemistry
55. What is a redox reaction?
electron transfer
56. Define oxidation, reduction, oxidant and reductant.
Oxidant causes oxidation (loss of electron) and is itself reduced (gain of electron).
vice versa
57. State the rules for oxidation numbers.
elemental allotropes all = 0
H = +1
O = -2
sum of oxidation numbers in an ion = its charge
58. How do you write a balanced half equation?
KOHES(B)
59. What is a galvanic cell?
spontaneous redox reaction occuring in two separate half cells with electrons moving through an external circuit and a salt bridge.
60. Explain the function of a salt bridge.
keep the two cells electro-neutral and "completes the circuit"
61. Why are the half cells separated in a galvanic cell?
to allow the energy possessed by the moving electrons to be harnessed [battery]
62. Assign polarities to the cathode and the anode.
Cathode = +
Anode = -
63. Explain the properties that an electrode must have.
Conductive
64. Explain the choice of electrode if
a) one member of the conjugate pair in a half cell is a metal
the metal
b) no metal is present
inert [graphite or platinum]
c) one member of the conjugate pair is a gas
inert [assuming the other is aqueous]
65. Explain how the electrochemical series can be used to predict redox reactions.
strongest oxidant react with strongest reductant
66. Define potential difference.
difference in E-nought
67. List three reasons why a predicted redox reaction does not occur.
non-standard conditions
rate of reaction is too slow
side reactions
68. Explain the difference between a primary and a secondary cell.
secondary cells can be recharged [products of discharge remain on the electrode]
primary cells cannot be recharged [products of discharge migrate away from the electrode]
69. Explain why fuel cells are considered more efficient than power stations.
direct conversion of chemical energy to electrical is more efficient than the chemical -> thermal -> thermal -> mechanical -> electrical
70. Why are secondary cells able to be recharged but not primary cells?
see 68 brackets.
71. How do you recharge a secondary cell?
apply a voltage in reverse direction of discharge at greater magnitude than recharge
THEN MAGIKS
72. What is the difference between a fuel cell and primary/secondary cells?
fuel cell supply energy so long as fuel is fed. electrochemical cells eventually run out of reactants/establish equilibrium and "go flat".
73. What is electrolysis?
non-sponaneous redox reactions by applying a voltage
74. Compare the similarities and differences between an electrolytic cell and a galvanic cell.
electrolytic cell is a galvanic cell in reverse, with the voltmeter replaced by a battery placed in reverse orientation
75. Explain why the products of an electrolytic cell must not come into contact.
the products of electrolytic cells will spontaneously react
76. In some cases, an aqueous electrolyte cannot be used instead of a molten one. Explain.
water can act as oxidant and reductant, hence in some cases where water is a stronger oxidant/reductant than the reactant, water must not be present, hence molten reactants [or dissolved in cryolite or other solvents] are required as aqueous solutions are not adequate
77. If an electrolytic cell contained an electrolyte of an aqueous solution of aluminium nitrate, zinc sulfate, lead nitrate and nickel sulfate, list in order which metals would form at the cathode.
lead->nickel->zinc->hydrogen bubblez
78. In general, what is the voltage needed to power an electrolytic cell?
greater than the potential difference between the two standard cells
79. What is a Faraday?
1 mole of electron
80. List Faraday’s Laws.
