Fuels Flashcards
(89 cards)
1
Q
Fuel definition
A
A fuel is a substance that releases a usable amount of energy when combusted
2
Q
Natural greenhouse effect
A
Naturally occuring molecules e.g co2, ch4 are greenhouse gases which trap infra red radiation that would otherwise be radiated from earth into space
Increases temp of lower atmosphere
3
Q
Greenhouse gas definition
A
Gases that contribute to the greenhouse effect
4
Q
Problems caused by enhance greenhouse effect
A
Inc. amount of greenhouse gases in atmosphere
Inc. global warming
Inc. atmospheric temp
Inc. natural disasters and weather extremes
5
Q
Complete combustion
A
Fuel + oxygen-> carbon dioxide + water
6
Q
Incomplete combustion
A
Fuel + oxygen-> carbon monoxide + water
OR
Fuel+ oxygen-> carbon + water
7
Q
-ve delta H
A
Exothermic
8
Q
+ve delta H
A
Endothermic
9
Q
Heat of combustion
A
Describes heat released per gram or per mole of fuel
Units= kJ/mol
10
Q
Acid- base reactions
A
Involve the transfer of a proton from one substance (acid) to another (base)
11
Q
Acid
A
Proton donor
12
Q
Base
A
Proton acceptor
13
Q
Amphoteric meaning and e.g
A
Substances that can react as either an acid or base
E.g water
14
Q
Base+ acid ->
A
Water and salt
15
Q
Carbonate+ acid->
A
Salt+ carbon dioxide+ water
16
Q
Water+ acid ->
A
Hydronium + anion
17
Q
Water + alkali ->
A
Hydroxide+ cation
18
Q
Oxidation
A
Loss of electrons
19
Q
Why are metal+ acid -> salt+ hydrogen not considered acid base reactions
A
B/c no transfer of H+
20
Q
Metal + steam
A
Metal oxide + hydrogen
21
Q
Metal + water->
A
Metal hydroxide + hydrogen
22
Q
Gravimetric analysis
A
Technique that describes the amount of analyse using the mass before and/or the physical/ chemical change
23
Q
What is the analyte
A
The ion being analysed
24
Q
What do you need to do to make sure the precipitate is pure
A
Rinse with dissolved water to remove soluble ions and ‘dry to constant mass’ to ensure all water has been removed
25
To determine concentration of Cl- in mineral water, why do you add excess silver nitrate to mineral water?
If silver nitrate is in excess, means there is more than enough silver ions present to precipitate all of Cl- ions out of solution
26
Sources of error gravimetric analysis
-errors inc. final mass measurement and cause overestimation of mass of analyte
- error that Dec. mass of measurement cause underestimation of mass of analyte
27
Types of analysis
Quantitative analysis, quantitative data, qualitative analysis, qualitative data
28
Types of error
Systematic, random, personal, parallax
29
Quantitative analysis
Technique that identify amount of substance present
30
Quantitative data
Data which provides a numerical value
31
Qualitative analysis
Technique that determines the composition of a sample
32
Qualitative data
Descriptive data collected based on observations taken during the experiment
33
Systematic error
An error in measurement by same amount in the same direction every time
34
Random error
An error in measurement that differs in amount each time experiment is conducted
35
Personal error
Result of mistakes in method.
SHOULD NOT BE INCLUDED IN ANALYSIS
36
Parallax error
Systematic error if meniscus is consistently read from wrong height
37
How to manage systematic errors
Calibrate equipment so that all measurements reflect the the true value being measured
38
How to manage random errors
Increase the resolution of measuring apparatus, which reduces the impact of subjective judgements and CV effectively
39
Should personal errors be included in the analysis
NO
40
Validity
Refers to whether an experiment correctly investigates what it aims or claims to investigate
41
Accuracy
Refers to whether measurements are close to the true value
Achieved when systematic error is minimised
42
Precision
Refers to whether measurements are close to their mean values, whether or not this is the true value
Achieved when random error is minimised
43
What is collision theory
For chemical reactions to occur, reactant particles must collide
Must be correct orientation + sufficient energy to disrupt bonds in their molecules
If colliding particles overcome the repulsion and have sufficient energy, this forms new bonds
44
Activation energy
The minimum amount of energy required for a reaction to take place
45
What must happen for a reaction to occur
Particles must have energy equal to or greater than the AE.
Inc. number of particles with sufficient energy-> inc. ROR
46
Factors affecting successful collision
Correct orientation
Reactant particles must collide
With sufficient energy
47
Units of ROR
M= concentration
s= seconds
M/s
48
Factors affecting the rate of reaction
Surface area of solid reactants
Temp of reactants
Concentration of solution
Pressure of reactant gases
Presence of a catalyst
49
How does inc. SA impact ROR
Inc. SA-> inc. frequency of collisions-> inc. frequency of successful collisions-> inc. RoR
50
How does concentration impact RoR
Inc. concentration-> inc. frequency of collisions-> inc. frequency of successful collisions-> inc. ROR
51
How does pressure impact RoR
Inc. pressure-> Dec. volume-> inc. frequency of collisions inc. frequency of successful collisions-> inc. RoR
52
What is RoR
Speed at which a reaction occurs
53
What does the area under the curve represent in Maxwell Boltzmann
Represents particles in a reaction
54
Catalyst impact on RoR
Addition of catalyst-> inc. proportion of particles with energy equal to or greater than AE-> inc. frequency of collisions-> inc. frequency of successful collisions-> inc. RoR
55
Inc. temp impact on RoR
Inc. heat energy-> inc. proportion of particles with energy equal to or greater than AE-> inc. frequency of collisions-> inc. frequency of successful collisions-> inc. RoR
56
What does a catalyst do
Lowers the activation energy and remains unchanged
57
What is homogenous
Same state as reactants
58
What is heterogenous
Different state to reactants
59
What is a closed system
A system that is completely isolated from its environment.
System can have a transfer of energy but no transfer of matter
60
Why must a system be closed for equilibrium to reach
System must be closed to ensure no products/ reactants introduced or escaped
61
Dynamic equilibrium
Rate of forward reaction= rate of reverse reaction
Concentration of reactant DOES NOT EQUAL concentration of product ( remains the same)
62
Le chateliers principle
A system at equilibrium has a tendency to partially oppose every change that you make to it
63
What will addition of a catalyst do to equilibrium
WILL NOT SHIFT EQUILIBRIUM but will increase both forward and reverse reactions rate
64
Le chateliers principle- pressure
Change in pressure will only affect equilibrium if there is an IMBALANCE in number of moles of gas on each side of equation
65
What will happen in a dynamic equilibrium
There will be no observable change over time and no temp. Change
66
What is the haber process
An industrial method for synthesising ammonia from nitrogen and hydrogen gases
67
Conditions for haber process
Fe catalyst
Pressure of 200 atm
Temp. Of 450 degrees celsius
68
Importance of haber process
Produces ammonia which is crucial for fertilizers that are essential for modern agriculture
69
What do the conditions in the haber process allow
Allow forward reaction to be favoured and ammonia gas to be produced
70
Where is nitrogen sourced from
The air
71
Where is hydrogen sourced from
Natural gas
72
Haber process equation
3H2 (g) + N2 (g) <=> 2NH3 (g)
Delta H= -ve
73
Ideal conditions for haber process
350 degrees Celsius
Pressure 400 atm
74
Compromised conditions have process
450 degrees Celsius
Pressure 200 atm
Fe catalyst
75
What are the perfect conditions to achieve high yield of ammonia
Low temp
High pressure
76
Why is the temp. Increased in HP
Is system’s temp. Is lowered, RoR would also slow down and a high yield will take a longer time to produce (economical factor)
T/f a Fe catalyst is added to speed up RoR
77
Why is pressure decreased in HP
Maintaining high pressure is dangerous for those working in production and is expensive to run equipment
78
What does a concentration time graph show
Shows the change in concentration of each reactant and product over time
79
ROR equation
1/ time
80
What do you do if reactants are not present in stoichiometric ratio
-must find reactant that is completely used in reaction (limiting reagent) and which one is present in excess after reaction completes (excess reaction)
81
Which reactant determines how much product is formed
Limiting reagent
82
To convert from mmHg to kPa
Pressure/ 750 x 100
83
To convert from atm to kPa
Pressure/ 0.987 x 100
84
To convert from mmHg to atm
Pressure/ 750 x 0.987
85
Boyles Law
PV= k (k is constant)
P1V1= P2V2
86
Charle’s Law
V1/T1=V2/T2
V=kT ( T is in Kelvin and k is constant)
87
How many kelvin is 0 degrees
273K
88
How to find moles with volume and molar gas volume
N= V/ Vm
Or
N= V/24.8
89
Ideal gas equation
PV=nRT
P= pressure (kPa)
V= volume (L)
N= moles
R= 8.31 J/K/mol
T= temp. (Kelvin)
