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BMAT > chemistry > Flashcards

chemistry Flashcards

1
Q

what explains the trend seen in thermal stability of group 2 carbonates

A

Carbonate ions can be made unstable due to a cation (group 2 metal ion), causing the carbonate ion to be polarised (as it has electrons drawn towards itself). Polarisation distorts the carbonate ion and the more it is distorted, the less stable it will be. Larger cations (moving down group 2) cause less distortion because their electrons are spread out over a larger area. Therefore, the carbonate ion will be distorted less so it will be more stable.

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2
Q

strucutre of the atom

A

central nucleus (containing protons and neutrons) surrounded by electrons moving in shells/energy levels.

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3
Q

relative masses and charges of protons, neutrons and electrons, and recognise that most of the mass of an atom is in the nucleus.

A

mass of proton: 1
mass of neutron: 1
mass of electron: n/a

charge of proton: +1
charge of neutron: 0
charge of electron: -1

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4
Q

isotope

A

atoms of an element with the same number of protons but different numbers of neutrons (so having different mass numbers).

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5
Q

using

A

mass spectrometers

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6
Q

relative atomic mass symbol

A

Ar

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7
Q

elements are arranged in order of

A

increasing atomic number

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8
Q

alkali metals are

A

group 1

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9
Q

alkaline earth metals are

A

group 2

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10
Q

common non metals

A

group 16

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11
Q

halogens are

A

group 17

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12
Q

noble gases are

A

group 18

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13
Q

elements in the same group…

A

have similar chemical properties
increasing reactiivty down a metal group and decreasing reactivity down a non metal group

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14
Q

what factors affect pos of e

A

concentration of reactants/products, temperature, overall pressure

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15
Q

avogadros number gives

A

the number of particles of one mole of a substance

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16
Q

one mole of a substance is the what

A

Ar or Mr in grams

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17
Q

grams to moles

A

divide by Ar or Mr

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18
Q

moles to grams

A

multiply by Ar or Mr

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19
Q

1 tonne is

A

1000 kg

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20
Q

moles to number of atoms or molecules

A

multiply by avogadros (6.022 x 10^23)

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21
Q

amount of substance corresponds to

A

the number of moels of a substancce

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22
Q

empirical formula is

A

the simplest integer ratio of atoms in a compound. Find the empirical formula of a compound from a variety of data, such as the percentage composition by mass of the elements present or reacting masses

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23
Q

one mole of gas occupies what at a given rtp

A

24 dm cubed

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24
Q

percetnage yield

A

actual yield/theoretical yield x 100

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25
Q

oxidation is

A

gain of oxygen
loss of electrons

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26
Q

reduction is

A

removal of oxygen
gain of electrons

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27
Q

oxidising agent

A

gets reducted
does oxidising

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28
Q

reducing agent

A

gets oxidised
does reducing

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29
Q

how are ions formed

A

by transfer of electrons from atoms of metals to atoms of non-metals, and that these ions (of opposite charge) attract to form ionic compounds

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30
Q

when are roman numerals used

A

when an element can exist in more than one oxidation state

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31
Q

a covalent bond is

A

when atoms share one or more pairs of electrons, generally between non metals

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32
Q

metallic bonding is

A

solid metals exist as a giant structure of positively charged ions surrounded by delocalised (free) electrons.

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33
Q

small covalent molecules

A

water
ammonia
methane

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34
Q

giant covalent structures

A

diamond
graphite
silicon dioxide

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35
Q

what forces are ovecome in melting or boiling

A

intermolecular

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36
Q

chemical processes are require dto

A

displace consitiuent elements from their compounds

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37
Q

physical provesses are required to

A

separate mixtures, including miscible/immisicible liquids and dissolved/insoluble solids

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38
Q

an acid is a substance that can form

A

H+ ions or is a H+ donor

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39
Q

metal +

A

salt +

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40
Q

physical properties of group 1

A

are soft (they can be cut with a knife)
have relatively low melting points
have low densities

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41
Q

chemical properties of group 1

A

reaction with moist air
reaction with water

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42
Q

physical properties of group 17

A

simple molecules
2 halogen atoms joined by a single covalent bond
mp and bp increase going down group 7
the molecules become larger
the intermolecular forces become stronger
more energy is needed to overcome these forces

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43
Q

chemical properties of group 17

A

react with metals to produce salts
reactivity decreases going down the group

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44
Q

physical properties of group 18

A

inert
low densities

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45
Q

what is a displacement reaction

A

Displacement reactions involve a metal and the compound of a different metal. A more reactive metal will displace or push out a less reactive metal from its compound in a displacement reaction. The less reactive metal is left uncombined after the reaction. It is no longer chemically bonded to any other elements. It is now a pure element.

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46
Q

one mole of some acidic substances is able to form/donate

A

more than on emole of H+ ions
(mono-, di-, tri-, and polyprotic.)

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47
Q

a base is a substance

A

that can form OH- ins or that is an H+ acceptor

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48
Q

when do you use simple distillation

A

Distillation separates a liquid from a solution. For example, water can be separated from salty water by simple distillation. This method works because the water evaporates from the solution, but is then cooled and condensed in a condenser and collected in a separate container. The salt does not evaporate and so it stays behind.

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49
Q

when do you use fractonal distillation

A

Fractional distillation separates miscible liquids that have different boiling points. It is useful for separating ethanol from a mixture of ethanol and water, and for separating crude oil into different products such as petrol, diesel and kerosene.

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50
Q

when do you use paper chromatography

A

Chromatography can be used to separate mixtures of coloured compounds. Mixtures that are suitable for separation by chromatography include inks, dyes and colouring agents in food.

Simple chromatography is carried out on paper. A spot of the mixture is placed on a pencil line near the bottom of a piece of chromatography paper – the line must be in pencil because pencil is insoluble in water and so will not move as the chromatography progresses. The paper is then placed upright in a suitable solvent, such as water.

As the solvent soaks up the paper, it carries the mixtures with it. Different components of the mixture will move at different rates. This separates the mixture out.

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51
Q

when do you use a seperating funnel

A

separate immiscible liquids

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52
Q

when do you use centrifugation

A

to separate molecules of varying density A substance containing two different molecules, let’s say, is placed in a solution and put inside what’s called a centrifuge.

53
Q

when do you use filtration

A

This technique is used to separate an insoluble solid from a liquid. It can be used to obtain a product that is free from unreacted chemicals, by-products or solvent.

54
Q

when do you use evaporation

A

One way to separate a soluble solid from its solution is to make crystals. This involves evaporating the solution to a much smaller volume and then leaving it to cool. As the solution cools, crystals form, and these can be obtained by filtration.

55
Q

bond breaking is

A

endothermic

56
Q

bond making is

A

exothermic

57
Q

cathode

A

negative electrode

58
Q

anode

A

positive electrode

59
Q

describe electroloysis

A

the cations (positively charged ions) receive electrons (reduction) to change into atoms or molecules, and at the anode, the anions (negatively charged ions) lose electrons to form atoms or molecules (oxidation).

60
Q

crude oil is the main source of

A

hydrocarbons

61
Q

how is crude oil sepearted into fractions

A

fractional distillation

62
Q

alkanes general formula

A

CnH2n+2

63
Q

which are saturated

A

alkanes

64
Q

alkenes general formula

A

CnH2n

65
Q

addition reactions occur with which substances

A

hydrogen, halogen, hydrogen halides and steam

66
Q

addition polymerisation

A

alkenes or other molecules with a C=C bond may react with each other to form long-chain saturated molecules called polymers by addition reactions called polymerisation, and that the unsaturated molecules are called monomers.

67
Q

alcohol general formula

A

CnH2n+1OH

68
Q

carboxylic acids general formula

A

CnH2n+1COOH

69
Q

reactivity of a metal is linked to

A

its tendency to form positive ions and the ease of extraction of the metal.

70
Q

most metal ores are

A

the oxides of the metal

71
Q

extraction of metal requires

A

reduction processes

72
Q

common properties of transition metals include:

A

a. they are able to form stable ions in different oxidation states

b. they often form coloured compounds

c. they are often used as catalysts (as ions or atoms).

73
Q

the energy required for these processes: freezing, melting, boiling/evaporating, and condensing,

A

is related to the bonding and structure of the substance, including a consideration of intermolecular forces.

74
Q

hydrogen –

A

explodes with a ‘squeaky pop’ when a burning splint is held at the open end of a test tube

75
Q

oxygen –

A

relights a glowing splint

76
Q

carbon dioxide –

A

limewater turns cloudy when shaken with the gas

77
Q

electrode

A

a conductor through which electricity enters or leaves an object, substance, or region.

78
Q

carbonates –

A

using a dilute acid

79
Q

halides –

A

using an aqueous solution of silver nitrate in the presence of dilute nitric acid (chlorides form a white precipitate; bromides form a cream precipitate; iodides form a yellow precipitate)

80
Q

eletrolyte

A

a liquid or gel which contains ions and can be decomposed by electrolysis, e.g. that present in a battery.

81
Q

why is direct current used in electrlysis and not alternating current

A

Direct current deposits anions in the anode and cations in the cathode. Incase of an alternating current, the current would keep changing directions and would lead to an uneven distributuion of ions in the electrodes.

82
Q

Cu2+ forms a

A

blue precipitate.

83
Q

products of electrolysis in aqueous solutions

A

the water molecules dissociate producing H+ and OH- ions
These ions are also involved in the electrolysis process and their chemistry must be considered
We now have an electrolyte that contains ions from the compound plus ions from the water
Which ions get discharged and at which electrode depends on the relative reactivity of the elements involved.
anode (pos) negative ions
cathode (neg)
positively charged ions

84
Q

products of electrolysis in molten binary compounds

A

the metal is formed at the negative electrode
the non-metal element is formed at the positive electrode where the negative non metal ions are attracted

85
Q

Na flame test

A

yellow-orange

86
Q

K flame test

A

lilac

87
Q

trend in bp in crude oil

A

longer chains have higher

88
Q

trend in viscosity in crude oil

A

longer chains more viscous

89
Q

trend in flammability in crude oil

A

longer chain hydrocarbons are less votalie and less viscous than short chains

90
Q

cracking

A

Cracking is a technique used in oil refineries whereby large and complex hydrocarbon molecules are broken down into smaller and lighter components that are more useful for commercial or consumer use. Cracking is a critical stage in the process of refining crude oil.

91
Q

what are structural isomers

A

Structural isomers are those isomers in which the atoms are completely arranged in a different order with the same molecular formulas. These are the molecules having the same kind of molecular formula with different connectivities depending upon the order they are put together.

92
Q

homologous series

A

A homologous series refers to a series of carbon compounds which have a different number of carbon atoms.

93
Q

functional group

A

a substituent or moiety in a molecule that causes the molecule’s characteristic chemical reactions.

94
Q

test for unsaturation

A

In this test when bromine solution is added to the unsaturated hydrocarbon the brown colour disappears if the hydrocarbon is unsaturated. Bromine forms an addition product with the unsaturated hydrocarbon.

95
Q

condensation polymerisation

A

Condensation polymers form in a different way to addition polymers like poly(ethene). Instead of forming just the polymer molecule as the only product, two products form:

a polymer molecule
a small molecule, often water
One type of condensation polymers are polyesters.

96
Q

biogradeable polymers

A

a special class of polymer that breaks down after its intended purpose by bacterial decomposition process to result in natural byproducts such as gases (CO2, N2), water, biomass, and inorganic salts.

97
Q

non-biodegradeable polymers

A

Non-biodegradable polymers are those polymers that are cannot degraded by microorganisms.

98
Q

alcohols + sodium

A

salt + hydrogen

99
Q

chemical properties of carboxylic acids as those of weak acids

A

they do not fully dissociate

100
Q

carboxylic acids react with alochols in the presence of an acid catalyst to produce esters

A

dissolve in water to form acidic solutions with pH values less than 7
react with metals to form a salt and hydrogen
react with bases to form a salt and water
react with carbonates to form a salt, water and carbon dioxide

101
Q

compisition of dry air

A

oxygen and nitrogen

102
Q

origins of greenhouse gases

A

.

103
Q

effects of greenhouse gases

A

.

104
Q

origins of gaseous pollutants

A

.

105
Q

effects of gasesous pollutatns

A

.

106
Q

purpose of chlorine and fluroide ions in the treatment of drinking water

A

.

107
Q

greenhouse gases

A

.

108
Q

gaseous pollutants

A

.

109
Q

what happens when glucose monomers join up to make a polysachharide

A

they lose water in the condensation reactions.

110
Q

Hydrolysis is the process of splitting molecules using water.

Polymers can be broken down to produce smaller molecules.

Which of the following is a product of protein hydrolysis?

A

whichever shows an amino acid
N-H2
C-HR
C=OOH

111
Q

Why would switching off the circuit between resistance readings improve the quality of results?

A

As you keep a circuit switched on, more current flows through and this transfers energy to the metal wire by conduction. The wire heats up as a result. This can cause the resistance of the wire to increase. As a result, it makes sense to turn the circuit off and let the wire cool between readings.

112
Q

Breeders use cell engineering methods to obtain

A

hybrid cells and growing hybrids from them

113
Q

origins of greenhouse gases

A

fossil fuel combustion

114
Q

effects of greenhouse gases

A

greenhouse effect
rising temps
ice caps melting

115
Q

origins of gaseous pollutants

A

fossil fuel combustion

116
Q

effects of gasesous pollutatns

A

myocardial infarction, stroke, heart failure, ecological damage

117
Q

purpose of chlorine and fluroide ions in the treatment of drinking water

A

In addition to killing dangerous germs like bacteria, viruses, and parasites, chlorine also helps reduce offensive tastes and odors in water. Furthermore, the chemical helps to eliminate molds, slime, algae, and bacteria that grow in water supply reservoirs, storage tanks, and on the walls of water mains. fluroide helps to pevent tooth decay

118
Q

greenhouse gases

A

water vapour
ozone
nitrous oxide
methane
carbon dioxide

119
Q

gaseous pollutants

A

carbon oxides
sulphur oxides
nitrous oxides

120
Q

NO + H2O –>

A

no reaction as NO is considereed to be thermodynamically unstable

121
Q

is gold reactive

A

no extremely unreactive

122
Q

how does reactiivty impact ease of extraction

A

The less reactive a metal is the easier it is to extract. This is because lesser reactive compounds can often simply be extracted of their ore with carbon or carbon monoxide,

123
Q

can carbon displace alumnium

A

no

124
Q

When iron oxide is reacted with carbon monoxide to produce iron and carbon dioxide; does the iron undergoes an oxidation reaction

A

no the iron undergoes reduction; i.e. it gains electrons.

125
Q

can carbon displace zinc

A

yes and is therefore able to displace it

126
Q

disproportionation reaction definition

A

“the simultaneous oxidation and reduction of the same species in a reaction”

127
Q

what are heterogenous catalysts

A

chemical catalysts whose physical phase is different from the physical phase of the reactants and/or products that take part in the catalyzed chemical reaction. Typically, solid phase heterogeneous catalysts are employed in order to facilitate the chemical reaction between two gaseous reactants.

128
Q

what are homozygous catalysts

A

catalytic compounds that are in the same phase as the substances which are going into the reaction phase.

BMAT (4 decks)

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