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Final Chemistry Edexcel IGCSE - Hard Content > Hard Content > Flashcards

Hard Content Flashcards

1
Q

What is an exothermic reaction?

A

One that gives off heat energy into the surrounding

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2
Q

What is an endothermic reaction?

A

One that takes in heat energy from the surroundings

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3
Q

What is the enthalpy change?

A

the overall energy change in a reaction?

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4
Q

What is the enthalpy change in an exothermic reaction?

A

negative because energy is given out

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5
Q

What is the enthalpy change in an endothermic reaction?

A

positive because energy is taken in

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6
Q

How can you calculate heat energy transferred?

A

mass of liquid being heated x shc x change in temp

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7
Q

how do you calculate molar enthalpy change?

A

molar enthalpy change = -energy transferred / moles

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8
Q

Why is bond breaking endothermic?

A

the energy used to break the bonds is greater that the energy released forming them

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9
Q

Why is making bonds exothermic?

A

the energy released making the bonds is greater than the energy used to make them

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10
Q

how can you calculate bond energies?

A

total energy absorbed to break bonds - total energy released to make bonds

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11
Q

what are two examples of reversible reactions?

A

copper sulfate + water -> hydrated copper sulfate

ammonia + hydrogen chloride -> ammonium chloride

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12
Q

what is equilibrium

A

the state of a chemical reaction in which the forward and reverse reactions are occurring at the same rate, but the concentrations of the reactants and products remain the same

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13
Q

If the equilibrium lies to the left?

A

mainly reactants, little products

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14
Q

if the equilibrium lies to the right?

A

mainly products, little reactants

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15
Q

reactant concentration is increased:

A

reaction forming products is favoured and equilibrium shifts

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16
Q

product concentration is favoured:

A

reaction forming reactants favoured and equilibrium shifts

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17
Q

temperature of reaction is increased (equilibrium):

A

endothermic reaction will be favoured

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18
Q

temperature of reaction is decreased (equilibrium):

A

exothermic reaction will be favoured

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19
Q

pressure of reaction is increased (equilibrium):

A

side of reaction with fewer gas moles favoured

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20
Q

pressure of reaction is decreased (equilibrium):

A

side of reaction with more gas moles faovured

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21
Q

what is ionic bonding?

A

the strong electrostatic attraction between positive an negative ions (metal and non metal)

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22
Q

When an ionic compound is formed….

A

electrons are transferred from a metal to the non metal to form positive and negative ions

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23
Q

carbonate:

A

Co3 2-

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24
Q

nitrate:

A

NO3 -

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25
ammonium:
NH4 +
26
hydroxide:
OH-
27
sulphate:
SO4 2-
28
what is the boiling and melting point of ionic compounds and why?
high, giant ionic lattice, strong ionic bonding, lots of energy to overcome
29
do ionic compounds conduct electricity?
Yes molten or dissolved as there are mobile delocalised electrons, no as a solid.
30
why are ionic compounds brittle
when a lattice layer is hit, a layer of ions is shifted so that ions with the same charge are lined up together and they then repel eachother
31
what are covalent bonds?
the strong electrostatic connection between nuclei and a shared pair of electrons
32
what is the boiling point of simple covalent molecules?
low because they have strong covalent bonds but weak IMF which require little energy to overcome
33
do simple covalent structures conduct electricity?
no because the molecules are neutral and carry no charge
34
what is the boiling point of giant covalent substances?
high, giant covalent lattice, strong covalent bonds, lots of energy to break
35
what is the conductivity of graphite?
can conduct as it has mobile delocalised electrons
36
how can you calculate percentage yield?
(actual/calculated) x 100
37
what are three possible reasons for percentage yield being less than 100%
1. reaction may be reversible 2. side reactions may have occured 3. products may be lost (i.e., time taken putting on bung)
38
what equation links gas moles, moles and volume?
moles = volume/24 dm3
39
what equation links moles, volume and concentration?
moles = conc x vol
40
electrode:
terminal at which electricity enters of leaves the electrode
41
anion:
a negatively charged particle
42
cation:
positively charged particle
43
cathode:
the negative electrode
44
anode:
positively charged electrode
45
electrolysis:
the splitting up of an ionic compound to form two new products using electricity
46
what occurs at the cathode?
attracts cations, reduction occurs, metal is formed
47
what occurs at the anode?
attracts negative anions, oxidation occurs, a non metal covalent molecule is formed
48
what three substances can beat H+ at the cathode?
copper, silver, gold
49
what three substances can beat OH- at the anode?
bromine, iodine, chlorine
50
list the reactivity series
potassium, sodium, lithium, calcium, magnesium, aluminium, carbon, zinc, iron, hydrogen, copper, silver, gold
51
how are metals above carbon extracted from their ore?
electrolysis
52
how are metals below carbon extracted from their ore?
displacement with carbon
53
4 uses of copper:
unreactive - piped, conducts electricity - wires, heat conductor - pans, antibacterial - hospital surfaces
54
2 uses of aluminium:
low density - aircrafts, aluminium oxide layer makes it unreactive - pans
55
one use of low carbon steel:
strong and malleable - bridges (can rust)
56
one use of high carbon steel:
very strong - cutting tools
57
one use of stainless steel:
corrosion resistant - cutlery and kitchen sinks
58
colour change of methyl orange:
acid - red, base - yellow
59
colour change of phenolphthalein:
acid - colourless, base - pink
60
colour change of red litmus
acid - red, base - blue
61
colour change of blue litmus
acid - red, base - blue
62
acid + metal ->
salt + hydrogen
63
acid + metal oxide ->
salt + water
64
acid + metal carbonate ->
salt + water + carbon dioxide
65
what is the SNAP rule?
sodium, nitrate, aluminium and potassium salts are soluble
66
what is the INCH rule?
insoluble carbonates and hydroxides except for snap salts
67
What is the ClasPbAg rule?
Chlorides are soluble except lead and silver
68
what is the SoSuBaCa rule?
soluble sulphates except for barium and calcium
69
What does a precipitation reaction make?
sol + sol -> insol + sol
70
What are the 6 steps to making a soluble salt from solid metal/excess base method?
1. combine excess metal with acid 2. add until bubbling stops/excess remains 3. filter out metal 4. boil off half to make saturated solution 5. allow rest to evaporate 6. filter excess liquid, dab crystals, leave on windowsill
71
What are the five steps to making an insoluble salt?
1. dissolve soluble salts in water 2. combine two salt solutions 3. filter, keep precipitate and discard solution 4. wash precipitate 5. allow to dry on windowsill
72
lithium flame test:
red
73
sodium flame test:
yellow
74
potassium flame test:
lilac
75
calcium flame test:
orange/red
76
copper(II):
blue/green
77
what is the test for cations?
add sodium hydroxide
78
copper test for cations:
light blue precipitate
79
iron (II) test for cations:
dark green precipitate
80
iron (III) test for cations:
dark orange precipitate
81
test for ammonium gas:
damp red litmus -> blue
82
testing for carbonates:
add dilute HCl and it will produce Co2
83
testing for sulphates:
add HCl then Barium Chloride (white precipitate)
84
testing for halides
nitric acid, then silver nitrate - Cl=white Br=cream I=yellow
85
test for chlorine
bleaches damp litmus
86
general formula for alkanes:
CnH2n+2
87
full name of alkane with two carbons:
ethane
88
root of names of hydrocarbons (1-6)
eth, meth, prop, but, pent, hex
89
structural isomers:
same molecular formula but different displayed formula
90
alkane + bromine ->
bromo(alkane) + hydrogen bromide
91
what is required for a bromine and alkane to react?
UV light
92
describe the production of crude oil:
remains of marine plants and animals sink t bottom of ocean millions of years ago. they became buried preventing them from rotting. gradually became sedimentary rock, heat and pressure then built up causing them to become crude oil and natural gas
93
from bottom to top, what are the fractions of fractional distillation?
bitumen, fuel oil, diesel, kerosene, gasoline, refinery gas
94
what are the 3 steps to crude oil fractional distillation?
1. crude oil is heated and vapourised 2. vapour is pumped into column 3. fractions condense at height where temp in column is lower than BP
95
general formula of alkenes:
CnH2n
96
are alkenes saturated or unsaturated
unsaturated
97
what is the name of the alkene with 3 carbon atoms?
propene
98
what is the colour change of alkenes + bromine?
orange -> colourless
99
what is the reaction between alkenes and bromine called?
addition
100
ethene + bromine ->
dibromomethane
101
what is cracking?
the breaking down of long chain alkanes that are in surplus to high demand smaller chain alkanes
102
what are two requirements for cracking?
600-700 degrees and aluminium oxide catalyst
103
what is the general formula of alcohols?
CnH2n+1OH
104
what does the oxidation reaction of ethanol require and produce?
acebacters, ethanoic acid
105
what is the general formula of carboxylic acids?
CnH2nO2
106
What is the functional group fo carboxylic acids?
C = O \ O - H
107
Carboxylic Acid + metal ->
salt + hydrogen
108
Carboxylic Acid + metal carbonate ->
salt + water + carbon dioxide
109
Carboxylic Acid + alcohol ->
ester + water
110
how do you name an ester?
alcohol becomes first part (-yl), the Carboxylic Acid becomes the second bit (-anoate)
111
How do you prepare a sample of an ester?
sulphuric acid + ethanol + ethnic acid in hot water bath with tube covered in cling film, leave for ten minutes. pour contents into sodium carbonate, ester will be visible as oily droplets

Final Chemistry Edexcel IGCSE - Hard Content (1 decks)

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