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Chemistry Flashcards

1
Q

Chem: what is the equation for atom economy

A

Mr of desired products / mr of total products x 100

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2
Q

Chem: what type of atoms and what happens in covalent bonding

A

2 non-metals, sharing electrons

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3
Q

Chem: what happens in metallic bonding and in what type of atoms

A

Positive metal ions in a sea of delocalised negative electrons, in metals

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4
Q

Chem: what happens in ionic bonding and in what type of atoms

A

Gives/takes electrons, metals and non-metals

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5
Q

Chem: what is a activation energy

A

The minimum energy required to start a chemical reaction

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6
Q

Chem. what is an energy profile

A

A graph showing energy change during a chemical reaction

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7
Q

Chem: what is an exothermic reaction

A

A chemical reaction that releases energy

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8
Q

Chem: what is an endothermic chemical reaction

A

A chemical reaction that takes in energy

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9
Q

Chem: what happens in a chemical reaction

A

Bonds are broken and formed and atoms are rearranged

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10
Q

Chem: how thick is one nm in terms of atoms

A

10 atoms thick

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11
Q

Chem: order in terms of size, from smallest to largest, coarse particles, nano particles and fine particles

A

Smallest - largest: nanoparticles, fine particles, coarse particles

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12
Q

Chem: what is the size of coarse particles

A

2500 to 10000 nm

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13
Q

Chem: what is the size of fine particles

A

100 to 2500 nm

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14
Q

Chem: what is the size of nano particles

A

1 to 100 nm thick

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15
Q

Chem: the the anode the positive or negative electrode in electrolysis

A

Positive

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16
Q

Chem: is the cathode positive or negative in electrolysis

A

Negative

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17
Q

Chem: is an anion positive or negative

A

Negative

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18
Q

Chem: is a cation positive or negative

A

Positive

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19
Q

Chem: what happenes at the negative electrode in electrolysis of aqueous solutions

A

Hydrogen, if the metal is more reactive than it
Also electrons transferred to ion to make it an atom

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20
Q

Chem: is electrolysis of aqueous solutions what happens at the positive electrode

A

Oxygen produced, unless halide present then it is produced
Electron transferred from ion to positive electrode

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21
Q

Chem: what is an aqueous solution

A

Something dissolved in water

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22
Q

Chem: what is the definition of electrolysis

A

Electrolysis is the process of splitting ionic compounds using electric current

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23
Q

Chem: how do you work out moles of an atom

A

Moles= mass / formula mass

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24
Q

Chem: how do you work out the formula mass (Mr) of a molecule

A

It is the sum of the elements in the molecule

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25
Q

Chem work out the Mr of K ₂O if the formula mass of of K is 39 and O is 16

A

39+39+16=94

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26
Q

Chem: How do you write ionic equations

A

Split the equation so
- NaOH ( aq ) + HNO 3 ( aq ) → NaNO 3 ( aq ) + H 2 O ( l )
Would become - Na + OH ( aq ) + H + NO 3 ( aq ) → Na + NO 3 ( aq ) + H 2 + O ( l )
Then cross out the portions that do not change their charge, this becomes
- OH ( aq ) + H → H 2 O ( l )

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27
Q

Chem: what is an ionic equation

A

It is a chemical equation with all of the things that do not change state removed

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28
Q

Chem: what are hydrocarbons

A

They are molecules made up of hydrocarbons

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29
Q

Chem: what is oxidation

A

Oxidation is the loss of electrons

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30
Q

Chem: what is reduction

A

It is the gain of electrons

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31
Q

Chem: in electrolysis does reduction or oxidation occur at the positive electrode

A

Oxidation

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32
Q

Chem: in electrolysis does oxidation or reduction occur at the negative electrode

A

Reduction

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33
Q

Chem: what is a half equation

A

Electrons are represented, they are 2 equations that show the 2 sided of a redox reaction (reactions with both oxidation and reduction)

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34
Q

Chem: what is the equation for complete combustion

A

Hydrocarbon + oxygen -> carbon doxide + water

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35
Q

Chem: what is the equation for incomplete combustion

A

Hydrocarbon + oxygen -> carbon doxide + water + carbon monoxide

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36
Q

Chem: what is the definition of carbon footprint

A

this is the total amount of carbon dioxide and other greenhouse gases that are emitted over the full lifecycle of a product, service or event

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37
Q

Chem what is carbon foorptprint offsetting

A

Say you buy a plane ticket, planting trees to offset the greenhouse gasses released by the journey

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38
Q

Chem: what is the order of events for the formation of life

A

Volcanoes, oceans, algiae, plants, animals

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39
Q

Chem: what are the percentages of gasses in the atmosphere

A

Nitrogen-78, oxygen-21, other gasses-1

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40
Q

Chem: what are alkanes

A

They all end in ‘ane’
They are hydrocarbons
There formula is CnH2n+2

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41
Q

Chem: what are the 4 ankanes you need to remember

A

Methane, ethane, propane, butane

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42
Q

Chem: what is crude oil made of

A

Fossilised plankton

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43
Q

Chem: what is the definition of a mixture

A

A substance composed of 2 or more differeent compounds or elements not chemically bonded

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44
Q

Chem: what is ionic bonding and in what types of elements does it occur

A

Giving/taking electrons
Between metals and non metals

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45
Q

Chem: what is covalent bonding and in what type of elements does it occur

A

Sharing electrons
2 non metals

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46
Q

Chem: what is metallic bonding and in what type of elements does it occur

A

Sea of delocalised electrons
Metals

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47
Q

Chem: what are the properties of covalently bonded substances

A

Non-conductive(no charged particles that can carry a charge), low melting point,

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48
Q

Chem: what are the properties of ionically bonded substances

A

Conduct when dissolved in water, hard and brittle, high melting and boiling points.

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49
Q

Chem: what defines potable water

A

It is safe to drink, it should have low levels of dissolved salts and of microbes.

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50
Q

Chem: what are the 2 ways of getting potable water from salt water

A

Distillation , reverse osmosis

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51
Q

Chem: what is reverse osmosis

A

It is osmosis where the water moves from low to high concentration because of large amounts of pressure

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52
Q

Chem: what is distillation

A

Where a liquid is evaporated and collected from a mixture

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53
Q

Chem: what are the 3 ways water us steralized

A

UV, chlorine, ozone

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54
Q

Chem: what is pure water

A

Water that is not in a mixture

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55
Q

Chem: how many cm3 in a dm3

A

1000

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56
Q

Chem: what is collision theory

A

A theory that for a reaction to occurr particles must collide with enough energy

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57
Q

Chem: what explains why reactions happen at different rates

A

Collision theory

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58
Q

Chem: how do catalysts work

A

They change the reaction pathway

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59
Q

Chem: what are the 5 factors that affect rate of reaction

A

-temp
-concentration
-catalyst
-pressure
-surface area

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60
Q

Chem/bio: how do enzymes make things react

A

They lower the activation energy

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61
Q

Chem: what is a the difference between weak and strong acids

A

Weak acids have low amounts of ionised hydrogen ions, whereas in strong acids there is a large amount of ionised hydrogen ions

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62
Q

chem: what is a mole

A

1 mol is the amount of substance that contains the same number of particles as there are atoms in 12.0 g of carbon-12, its the 6.02 x10^23 atoms of carbon 12

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63
Q

chem: what is percentage yeild

A

actual yield / theoretical yield x 100

64
Q

chem: what is the equation for relative formula mass

A

adding up all of the relative atomic masses of the atoms in a formula

65
Q

Chem: what is the difference in amount of hydrogen ions between PH 2 and PH 1

A

10x, each jump is a gap of 10x as it is what i think is a log arythem

66
Q

Chem: what hydrogen ions constitute acids, are they positive or negative

A

H+ ions

67
Q

Chem: what hydrogen ions constitute alkalise, shat charge are they

A

OH- ions

68
Q

chem: in electrolysis does reduction happen at the cathode or anode

A

cathode

69
Q

chem: in electrolysis does oxidation happen at the cathode or anode

A

anode

70
Q

Chem: what is the difference between giant and simple covalent bonding

A

Simple covalent - fixed number of atoms in the structure, giant covalent - undefined amount of atoms.

71
Q

Chem: why do simple covalent compounds have low melting and boiling points

A

The have weak intermolecular forces, this means less energy is needed to overcome these forces

72
Q

Chem: what is the difference between atomic and intermolecular forces

A

Atomic forces are forces within an atom and intermolecular forces are the forces between atoms.

73
Q

Chem: what does equilibrium mean

A

The forward and reverse reactions occur at the same rate in a closed system

74
Q

Chem: what are the properties of simple covalent compounds

A

Low melting and boiling point, do not conduct

75
Q

Chem: what are the properties of giant covalent

A

High melting and boiling point.

76
Q

Chem: for equilibrium, does the amount of products and reactants have to be equal

A

No the only must remain the same, individually

77
Q

Chem: what are the properties of ionic compounds

A

High melting and boiling points, when molten or dissolved the conduct, when solid the have poor conductivity

78
Q

Chem: what are the properties of metallic bonding

A

Conductivity

79
Q

Chem: what are the 2 principles of Le Chateliers Principle

A
  • If the conditions change then the posision of equalibrium changes
  • If the conditions change then the system responds to counteract the change.
80
Q

Chem: define concentration

A

Amount of particles in a given volume

81
Q

Chem: to increase the rate of reaction for an Exothermic reaction by changing temp what do you do, cool or heat? Why?

A

Cool, if there is less energy in the surroundings it is easier for the reaction to give out energy.

82
Q

Chem: what is a solvent

A

A liquid in which a solid dissolves

83
Q

Chem: what is a solute

A

Dissolved solid

84
Q

Chem: what is a solution

A

A liquid which contains a dissolved solid

85
Q

Chem: what are the 5 ways of separating mixtures

A
  • crystallisation
  • filtration
  • chromatography
  • simple distillation
  • fractional distilation
86
Q

Chem: explain fractional distillation

A

A mixture of several substances is separated by distilling the mixture and then evaporating and collecting the individual components using their individual boiling points

87
Q

Chem: define distillation

A

Purifying a liquid by heating and cooling

88
Q

Chem: explain simple distillation

A

It separates 2 liquids with different boiling points, the mixture with the lower boiling point is boiled off and collected

89
Q

Chem: explain crystalizatiom

A

To separate a soluble substance from a solvent, evaporate the solvent to form crystals of the solute

90
Q

Chem: explain filtration

A

Used to separate an insoluble solid from a liquid, the mixture is put through a filtration device to collect the liquid and the solid/s

91
Q

Chem: explain chromatography

A

Used to separate mixtures of soluble substances in a solution, paper chromatography this works on the principle that some substances are more soluble

92
Q

Chem: what is the equation of concentration (used in titrations)

A

Concentration = moles / volume

93
Q

Chem: define decomposition

A

The process of breaking down

94
Q

Chem: what is thermal decomposition

A

A compound that breaks down when heated

95
Q

Chem: what are the 2 catalysts used in catalytic converters

A

Palladium and platinum

96
Q

Chem: what is dynamic equilibrium

A

It is equilibrium where both froward and backward reactions are still happening

97
Q

chem: what are the properties of the transition metals

A
  • they have high melting and boiling points
  • higher dencity
  • lower reactivity
  • greater strength and hardness
  • some of them can be used as catalysts
98
Q

chem: what is an acid

A

it is a substance that forms H+ ions when dissolved in water

99
Q

chem: waht is an alkali

A

it is a substance that forms OH- ions when dissolved in water

100
Q

chem: when reacting with other substances what charged ions do metal atoms form

A

posotive

101
Q

chem: what is the reactivity of a metal baced on

A

its ability to form its posotive ion

102
Q

chem: what is an ion

A

it is an atom or group of them that has any charge

103
Q

chem: what is a spectator ion

A

it is an ion that, in a reaction does not change its charge

104
Q

chem: what is the difference between an alkali and a base

A

a bace is an alkali that is soluable in water

105
Q

chem: when lithium reacts with water what happens

A

fizzes steadily and floats

106
Q

chem: when potassium reacts with water what happens

A

reacts quickly, hdrogen produced is instantly ignited and the metal ignites too, buring with a lilack flame

107
Q

chem: when sodium reacts with water what happens

A

fizzes rapidly and melts, moves around on the waters surface

108
Q

chem: why are metals less reactive than carbon extracted from their ore by carbon

A

the metal is reduced (looses its oxygen). carbon (in the form of coal) is used because it is cheap and abundent

109
Q

chem: when acids react with metals what is formed

A

hydrogen and a salt

110
Q

chem: what are the 3
types of base that acids can be neutralised with

A
  • metal carbonates
  • metal oxides
  • metal hydroxides
111
Q

chem: acid + metal oxide ->

A

salt + water

112
Q

chem: acid + metal hydroxide ->

A

salt + water

113
Q

chem: acid + metal carbonate ->

A

salt + water + carbon dioxide

114
Q

chem: what are the 3 ways of detecting the acidity or alkalinity of a substance

A
  • litmus paper
  • universal indicator
  • PH probe
115
Q

chem: what litmus paper is used to determine alkalinity

A

red litmus paper turns blue

116
Q

chem: what litmus paper is used to determine if a substance is acidic

A

blue litmus paper turns red

117
Q

chem: define titration

A

it is a technique that measures the volumes of acid and alkali solutions needed in a neutralization reaction

118
Q

chem: define a strong acid

A

it is an acid that when in water fully ionises, all of the acid breaks up to form H+ ions

119
Q

chem: what is a weak acid

A

it is an acid that when in water does not fully ionise, most are weak

120
Q

chem: what is the equation for fermentation

A

glucse -> ethanol + carbon dioxide

121
Q

chem: what is a limiting reactant and how do you find it

A

it is the reactant that is completely used up first, the reaction stops when this happens, you find it by finding the reactant with the lowest moles

122
Q

chem: if i fill 3 ballons with gas, one with 1 mole methane, one with 1 mole argon and one with 1 mole chlorine, which baloon will be the largest

A

they will all be the same size because at the same temperature and pressure one mole of any gas will have the same volume.

123
Q

chem: for titrations what is the range for concordant results

A

0.1 cm3

124
Q

chem: if a there is 20 cm3 of liquid in my measuring tube and it has an uncertanty of 1 cm3, write lower and upper bounds for the amount of liquid

A

19.5 < l < 20.5

125
Q

chem: Name three factors that make the percentage yield of a reaction less than 100%?

A

reaction is incomplete
waste products
side reactions

126
Q

chem: what makes a chemical cell have more voltage/potential difference

A

more difference in reactivity will result in more voltage

127
Q

chem: what happens to a chemical cell when you change the electrode

A

changing the electrode will change the reactions that happen at each electrode and so change the voltage

128
Q

chem: what makes a chemical cell non - rechargable

A

irreversable chemical reactions take place at the elctrodes, as soon as the one of the reactants has run out electrisity cannot be produced.

129
Q

chem: what makes a chemical cell rechargable

A

connection to an electric current reverses the reactions that occured to produce electrisity and recharges the cell

130
Q

chem: what are fuel cells

A

they produce electrical energy by reacting a fuel (often hydrogen) with oxygen (e.g. from the air), when this happens a current is produced and a current will continue to be produced unitll the fuel runs out.

131
Q

chem: what are the pros of fuel cells

A

they have high efficiency
they can produce less polution
they are reliable as they have no moving parts
they can be compact

132
Q

chem: hydrogen fuel cells vs petrol, which has a higher energy per gram

A

hydrogen fuel cells

133
Q

Chem: what is a formulation

A

It is a mixture of chemicals designed as a useful product, paint is one example

134
Q

Chem: if a change of state happens and the temperature increases during the change of state what can we say about the substance

A

It is impure or a mixture

135
Q

Chem: what is Rf in chromatography

A

It is the retention factor, its equation is distance traveled by dye(compound) / distance traveled by solvent

136
Q

Chem: what is chromatography used for

A

It is used to distinguish between pure and impure substances

137
Q

chem: why are small covalent molecules liquids or gasses at room temperature

A
  • when molecules melt or boil it is the intermolecular forces that break
  • these intermolecular forces are weak in simple covalent substances
138
Q

chem: define alloys

A

they are combinations of 2 or more elements when one of them is a metal

139
Q

chem: what is the difference between metals and alloys

A

alloys are:
- stronger than metals
- contain other elements
- harder
- the layers in alloys are distorted

140
Q

chem: what are the 2 types of conductor

A

heat - delocalized electrons can carry heat
electrical

141
Q

chem: what is an allotrope and what is an example of one

A

it is a different form or an element
diamond is an allotrope of carbon

142
Q

chem: what are the properties of diamond

A
  • they are hard, they have lots of covalent bonds
  • covalent bonds, every carbon atom is bonded to 4 others
  • diamond has not delocalized electrons that can conduct a charge
  • high melting and boiling point, it is very hard to break strong covalent bonds, hence high melting and boiling point
143
Q

chem: what are the properties of graphite

A
  • covalent bonds, each carbon atom is bonded to 3 others
  • soft, there are layers to graphene that are able to slide over one another
  • conductivity, each carbon atom forms 3 bonds, there is a delocalized electron for every carbon atom
144
Q

chem: what are the properties of graphene

A
  • conducts, delocalized electron can conduct
  • graphene is light but strong because it is one layer thick
145
Q

chem: what is a fullerine

A

they are allotropes of carbon that take hollow structures

146
Q

chem: what is a spherical fullerene called

A

it is called a buckminsterfullerene

147
Q

chem: what are some uses of buckminsterfullerenes

A

they can be used for:
- catalysts
- lubricants
- as vehicles for transporting drugs into our bodies

148
Q

chem: what are some properties of cylindrical fullerenes

A
  • strength, strong covalent bonds
  • conductivity
149
Q

chem: describe cylindrical fullerenes

A

they are called carbon nanotubes and take the shape of a cylinder, they are often called molecular wires because they have a tiny diameter but are very long

150
Q

chem: what are some uses of cylindrical fullerenes

A
  • electronics
  • nanotechnology
  • for strengthening materials
151
Q

chem: what are clumps of particles

A

matter often ‘clump’ up into small particles, the size of the clump gives it a different name:
- nanoparticles
- fine particles
- coarse particles

152
Q

Chem: why, when tennessine was discovered in 2010, was it not recognised as a new element until 2015

A

Because the discovery of the element must be repruducable

153
Q

Chem. what is the dependent variable

A

The one that the depends on the other variables

154
Q

Chem: how to calculate overall energy change

A

Energy in bonds of reactants - energy in the bonds of products = overall energy change
Energy in - energy out = overall energy change

155
Q

Chem: why do alloys conduct electricity worse than pure metals

A

Because the different elements in the alloy interrupt the lattice structure and make it harder for the electrons to move through the structure

156
Q

Chem: what equation links moles, volume and concentration

A

Conc = moles / volume

157
Q

Chem: explain how, in aluminium, electrons carry a change

A
  • delocalised electrons
  • they can carry a charge
  • they flow through the substance

all (16 decks)

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