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Higher Chemistry > Unit 1 > Flashcards

Unit 1 Flashcards

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1
Q

What is made when an alkaline metal is used to neutralise an acid

A

Salt and hydrogen

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2
Q

What is made when a metal carbonate is used to neutralise an acid

A

A salt , water and carbon dioxide

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3
Q

What is made when a metal oxide is used to neutralise an acid

A

Salt and water

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4
Q

What is made when a metal hydroxide is used to neutralise an acid

A

Salt and water

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5
Q

Name a method used to follow the rate of a reaction

A

Collecting gas over water

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6
Q

When does a reaction stop

A

When one of the reactants is used up

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7
Q

What is a limiting factor

A

The reactant that is in the shortest supply

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8
Q

What are the important factors associated with collision

A

Reactant particles have to collide
They must have sufficient energy to overcome the activation energy
Reactant particles must have the correct geometry

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9
Q

How do you recognise a concentration experiment

A

It will say H2O2 and/or KI

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10
Q

What is the aim of a concentration experiment

A

To determine the effects of changing KI concentration has on reaction rate

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11
Q

In a concentration experiment why is the potassium iodide solution acidified?

A

To supply h+ (aq) ions

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12
Q

What is the indicator used in the concentration experiment?

A

Starch solution

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13
Q

What is ommited from the concentration experiment equation

A

K+(aq) i.e spectator ions

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14
Q

What was timed in the concentration experiment

A

Start time when H2O2 is added

Stop time when blue black colour appears

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15
Q

Why is this a good experiment to measure concentration

A

The colour change from colourless to blue black is instant

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16
Q

What does an increase of temperature do to a reaction rate

A

It increases it as it increases the average number of molecules with q kinetic energy equal to or greater than the activation energy

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17
Q

How do you calculate the reaction rate

A

Rate=1
-
t

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18
Q

How long do explosive reactions take to come to completion

A

Come to completion almost instantly

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19
Q

What are photochemical reactions

A

In some chemical reactions light energy is used to increase the number reactant molecules with energy equal to or greater than the activation energy

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20
Q

Give an example the photochemical reaction

A

Photosynthesis: light energy is absorbed by chlorophyll to help co2 and h2o combine to make glucose and oxygen

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21
Q

What is activation energy

A

The minimum Connecticut energy required to produce a product

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22
Q

What is temperature

A

A measure of the average kinetic energy of all the reactant particles

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23
Q

On a potential energy diagram Will an exothermic reaction have a negative or a positive and enthalpy change

A

Negative as it gives off heat

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24
Q

What are some examples of exothermic reactions

A 
Combustion reactions neutralisation reactions
   MAZIT metal + Acid
   Metal oxide + Acid
   Metal carbonate +Acid
    Alkali +Acid
Displacement reaction
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25
Q

On a potential energy diagram Will an exothermic reaction have a negative or a positive and enthalpy change

A

Positive as it takes in heat

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26
Q

What are some examples of endothermic reactions

A

Dissolving certain salts (ammonium nitrate)

ethanolic acid + sodium hydrogen carbonate

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27
Q

What do small activation energies indicate

A

The reaction to take place at room temperature

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28
Q

What is an activated complex

A

As a reaction proceeds from reactants to products an intermediate state is reached at the top of the activation energy barrier at which a highly unstable complex called activation complex is formed
Activated complexes are very unstable and only exist for a very short amount of time

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29
Q

What is a catalyst

A

I cattle speeds up or slows down the rate of a chemical reaction without being used up or change during the reaction
a catalyst works by providing an alternate reaction pathway
This new reaction pathway has a lower activation energy

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30
Q

How does using a catalyst Lowering an activation energy speed up reactions

A

I lowering the activation energy and more of the reacting particles of kinetic energy is equal to or greater than the catalysed activation energy

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31
Q

What are the two types of catalyst

A

Homogeneous hertogeneos

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32
Q

What is a homogenous catalyst

A

Catalysts and the reactants are in the same state of matter

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33
Q

What is the hetogeneos catalyst

A

The catalyst and reactants are in a different state of matter

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34
Q

What are the three stages of a catalytic reaction

A

Adsorption reaction and desorption

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35
Q

What happens during adsorption

A

Reactants for my temporary bond with the catalyst. this weakens the bonds within the molecules thus the activation energy is lowered

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36
Q

What happens during reaction

A

The molecules react on the catalysts surface. the collision geometry is more favourable since one of the molecules is fixed

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37
Q

What happens during desorption

A

The product molecules leave the catalyst and the vacant site to be occupied by another reactant molecule. In other words catalysts can be reused

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38
Q

What is catalytic poisoning

A

Catalytic poisoning occurs when a substance (impurity) forms a strong bond with the active site on the surface of the catalyst so reducing the catalyst efficiency

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39
Q

How do you regenerate a poisoned catalyst

A

It involves cleaning the catalyst by removing impurities from activation site. this can be achieved by heating a catalyst and passing a gas over the catalyst that reacts with the impurities
E.g carbon removed by reacting it with oxygen for carbon dioxide

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40
Q

What is the catalyst Vanadium (V) oxide used for

A

It is used during the process: contact
The reaction is:
2SO2+O2 —–> 2S03
It is important during the manufacture of sulphuric acid

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41
Q

What is the catalyst iron used for

A

It is used during the process: Haber
The reaction is:
N2+3H3 —–> 2NH3
It is important during the manufacture of Ammonia

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42
Q

What is the catalyst platinum used for

A

It is used during the process: catalytic oxidisation of ammonia
The reaction is:
4NH3+5O2+4NO —–> 6H2O
It is important during the manufacture of nitric acid

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43
Q

What is the catalyst nickel used for

A

It is used during the process: Hydrogenation
The reaction is:
Unsaturated oils+H2 —–> saturated fats
It is important during the manufacture of Margerine

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44
Q

What is the catalyst aluminium silicate used for

A

It is used during the process: catalytic cracking
The reaction is:
Breaking down long chain carbon molecules
It is important during the manufacture of fuels and monomers for the plastics industry

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45
Q

What is metallic bonding

A

Metallic bonding occurs between atoms of metals
Metallic bonding is the electrostatic force of attraction between the positive metal core and the negatively charged delocalised electrons

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46
Q

What are the seven metallic elements among first 20 elements

A

Group 1- lithium sodium potassium
Group 2-Beryllium magnesium calcium
Group 3- aluminium

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47
Q

What does low electronegativity mean

A

Things like metals have very little attraction for bonding electrons

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48
Q

How can metallic lattice structures conduct electricity

A

Outer do you localised electrons can move freely through the overlapping energy levels

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49
Q

How are most metals, except for the exception of mercury, solids at room temperature

A

The bonds are relatively strong forces of attraction therefore metals are solid at room temperature

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50
Q

What do metals tend to be

A

Malleable and ductile

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51
Q

What type of bonding do metals do

A

Metallic

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52
Q

What two types of bonding do non metals do?

A

Covalent and monatomic

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53
Q

What two types of covalent bonding are there

A

Molecule and network

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54
Q

What are the 3 monatomic elements in group 0

A

Helium, neon, argon

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55
Q

Why are noble gases described as monatomic

A

They exist as one single gaseous atoms at room temperature

56
Q

How do we know there is a force of attraction between nobel gases

A

They can form solids and liquids

57
Q

What are the forces of attraction between noble gases known as

A

London Dispersion Fources of attraction

58
Q

What are discrete molecules

A

Small groups of non-metal atoms bonded together by strong covalent bonds (intramolecular forces of attraction)
These discreet molecules contain weak London Dispersion forces of attraction between their molecules that dictates their state of matter and physical properties

59
Q

How many discrete molecular elements are their within the first twenty elements

A

8

60
Q

What are London Dispersion forces of attraction?

A

Temporary dipole - induced dipole fouces of attraction

It is these intermolecular fources of attraction that dictates the melting and boiling point of the monatomic elements

61
Q

What are the 8 discrete molecular elements among the first 20 elements?

A 
Carbon ( in the form of fullerenes)
Nitrogen (N2)
Phosphorus (P4)
Oxygen (O2)
Sulphur (S8)
Fluorine (F2)
Chlorine (Cl2)
Hydrogen (H2)
62
Q

What do the boiling points of halogens and noble gases increase with

A

Atomic number
molecular mass
increasing London dispersion forces of attraction

63
Q

How many molecular solids are there on the first 20 elements of the periodic table

A

2
Phosphorus
sulphur

64
Q

What are molecule carbon fullerenes

A

Discrete covalent molecules. The smallest is spherical in shape, C60
The force of attraction between fullerenes is London Dispersion forces of attraction

65
Q

Name the covalent network elements in the first 20 elements of the period table

A

Group 3- boron
Group 4- carbon (dimond, graphite)
Silicon

66
Q

Describe boron as a covalent network element

A

Forma a structure of B12 groups that are inter-bonded with other B12 groups
The resulting element is almost as hard as diamond and is used in the manufacture of pyrex glassware
Able to withstand high temperatures

67
Q

Describe silicon and carbon (diamond) as a covalent network element

A

These structures have an infinite three dimensional network where each atom is covalently bonded (tetrahedral) to four other atoms
Very hard and rigid
Do not conduct as their elections are held in covalent bonds
High mpt

68
Q 
Describe carbon (graphite) 
as a covalent network element
A

Three covalent bonds from each carbon atom in one plane, forming hexagonal rings, the fourth unpaired electron is delocalised, forming weak bonds between layers
Aka strong bonds without layers but only weak interactions between layers
Graphite conducts through the ability of electrons to flow across layers

69
Q

What are some of the trends in the variations of the physical properties of the elements both across a period and down a group

A 
Melting point and boiling points 
density 
atomic size (or covalent radii)
ionisation energy 
electronegativity
70
Q

What are the trends in melting and boiling points in group 7 (the halogens) and group 0 (the noble gasses)

A

Increase with atomic number, molecular mass London Dispersion forces of attraction

71
Q

What are the trends in melting point and boiling points in group 1 (alkali metals)

A

Melting points decreased down group 1

72
Q

Why do melting points and alkali metals decrease as you go down

A

Because there are more shells of electrons the electron shells shield the delocalised electrons from the positive nuclear core which results in weaker electrostatic forces of attraction between the positively charged nucleus and the negatively charged do delocalised electrons

73
Q

What are the trends and melting and boiling points across a period

A

Across a period melting and boiling points increase to maximum near the centre of the period before decreasing towards group zero

74
Q

What is the trend in density across a period

A

It increases to a maximum towards the centre of the period before decreasing towards group 0

75
Q

What does density increase with down a group

A

Atomic number

76
Q

What is atomic size

A

It is the defined as the distance between the nuclei of two covalently bonded elements

77
Q

What can the distance between the nuclei be measured with

A

X-ray defraction

78
Q

Why is covalent radii period property

A

There are two discrete bonds

79
Q

Atomic size increases…

A

Down the group

80
Q

Atomic size decreases…

A

Across a period…

81
Q

What happens to the nuclear charge across a period

A

Increases

82
Q

What is first ionisation energy

A

the energy required to remove one mole of electrons from one mole of atoms in their gaseous state

83
Q

What is the formula for first ionisation energy

A

E(g)–>E(g)*+e-

84
Q

What type of process is first ionisation

A

Endothermic process

85
Q

What is the trend in the space between electrons nuclear core when going down to group

A

To outer electrons are further away from the positive nuclear charge

86
Q

There are increased electron shielding….

A

Due to added energy levels

87
Q

What does increased electron shielding result in

A

A decrease in the electrostatic force of attraction between the positive nucleus and negatively charged outer electron

88
Q

What is the trend and First ionisation energy going down the group

A

It decreases

89
Q

What is second ionisation energy?

A

The energy required to remove 1 mole of electrons from 1 mole of single positive ions in their gaseous state

90
Q

What is the formula for second ionisation energy

A

E(g) –> E2(g) +e-

91
Q

Why is there such a large increase in ionisation energies from the first ionisation energy to the second ionisation energy in elements in group 1

A

The first ionisation energy is for the removal of electron in the outer energy level
The second ionisation energy requires removing an electron from the inner stable octet with electrons,

92
Q

Why is it harder to remove electrons from an inner stable octet

A

They nearer to the positive nucleus and subject to lesser degree of electron shielding therefore a greater electrostatic force of attraction between the positive nucleus and the negative electrons so it requires much more energy to remove it

93
Q

What is electronegativity

A

The pulling power and atom has for bonded electrons

94
Q

How is a covalent bond formed

A

Are you sharing a pair of electrons between two atoms

95
Q

What is the trend in electronegativities down a group

A

They decrease

96
Q

What is the trend in electronegativities across a period

A

They increase

97
Q

Why do electronegativities decrease down a group

A

The outer electrons are further from the positive nucleus and subject to increased electron shielding due to the additional energy levels
Electrostatic forces of attraction are weaker and therefore have a weak attraction for bonding electrons i.e lower electronegativity

98
Q

Why does electronegativity increase across period

A

The positive Nicola charge increases resulting in increased electrostatic force of attraction for bonded electrons I.e increased electronegativity

99
Q

What are the three types of bonding

A

Metallic
Ionic
Covalent

100
Q

What are the two types of covalent bonding

A

Covalent molecular

Covalent network

101
Q

What are the two types of covalent molecular

A

Intermolecular

Intermolecular

102
Q

What are the two types of intramolecular bonding

A 
Non-polar
Polar covalent (perminent dipoles)
103
Q

What are the two types of intermolecular

A

Dipole-dipole

London Dispersion forces

104
Q

Name a special type of dipole-dipole bonding

A

Hydrogen bonding

105
Q

Describe ionic bonding

A

An electrostatic force of attraction between positive ions of metals (and some notable non metal ions like NH4*) with the negative ion of non-metals (or groups of non metals known as complex ions, for example So4^2-)

106
Q

Explain ionic bonding

A

The difference in electronegativitity between metals (low) and non metals (high) results in a transfer of electrons from the metal atom to the non metal atom so creats a positive metal ion and a negative non metal ion

107
Q

The greater the difference in electronegativity between the metal and non metals….

A

the greater the degree of ionic bonding

108
Q

What is the notable exception to all metal, non metal ions being solid at room temperature

A

Titanium chloride (TiCL2) is a liquid and therefore not subject to ionic bonding

109
Q

What are all ionic compounds at room temperature

A

Solid

110
Q

Describe covalent bonding

A

Occurs between non-metal elements (there are some notable exceptions for example titanium chloride)

111
Q

Describe non polar covalent bonds

A

These bonds result from non metal atoms in a molecule having the same electronegativitys
All molecules containing only non-polar covalent bonds are non polar covalent molecules

112
Q

Why are non popular covalent molecules gases, liquids or low melting point solids at room temperature

A

They have properties associated with London Dispersion forces of attraction

113
Q

Describe covalent bonds

A

These bonds result from non-metal atoms having different electronegativities
as a result these molecules are themselves polar

114
Q

Are polar bond subject to London dispersion forces of attraction?

A

Yes

115
Q

Describe polar molecules that are symmetrical

A

Molecules with polar covalent bonds but are symmetrical in shape are non-polar molecules as the polar charges cancel out

116
Q

What can differences in electronegativities indicate

A

Whether an atom is Ionic, polar covalent or non polar covalent
However this is not an exact science

117
Q

What are the three types of van de walls forces of attraction

A

1: London dispersion forces of attraction
2: permanent dipole forces of attraction
3: hydrogen bonding (a special version of two)

118
Q

What are permanent dipole - permanent dipole forces of attraction

A

These forces of attraction results from non-metal atoms and nonsymmetrical molecules having different electronegativities for example hydrogen sulphide
There generally stronger forces of attraction when compare to London dispersion forces of attraction

119
Q

What is hydrogen bonding

A

I a type of permanent dipole permanent dipole forces of attraction
These forces of attraction occur when non-metal atoms with very high electronegativities are bonded to hydrogen atoms

120
Q

Name molecules that contain nonpolar covalent bonds

A

All molecular elements
(H2, N2, O2, F2, Cl2, P4, S8)
phosphine PH3
Nitrogen chloride NCl3

121
Q

H2, N2, O2, F2, Cl2, P4, S8
phosphine PH3
Nitrogen chloride NCl3
What do all these molecules have in common

A

All these molecules contain nonpolar covalent bonds therefore they are nonpolar molecule subject to London dispersion forces of attraction

122
Q

Name some symmetrical molecules

A

Carbon dioxide CO2

carbon tetrachloride CCl4

123
Q

If I symmetrical molecule contains polar bonds what kind of molecule is it

A

A nonpolar molecule

124
Q

If a molecule contains non-polar bonds what kind of molecule is it

A

Nonpolar

125
Q

If a molecule is not symmetrical and contains polar bonds what kind of molecule is it

A

Polar

126
Q

In terms of symmetrical, polar and nonpolar molecules describe hydrocarbons

A

The boiling point of hydrocarbons increase with increased molecular mass and therefore increased London dispersion forces of attraction
All hydrocarbons are considered nonpolar molecules as they are all symmetrical
They are all nonpolar and therefore subject to London dispersion forces of attraction

127
Q

What does viscosity increased with

A

Increasing molecular size but molecules with hydrogen bonding show higher viscosity than expected

128
Q

What is miscibility?

A

Miscible liquids mix thoroughly without any visible dangers for example water and ethanol
Immiscible have a Boundry between them for example water and hexane
Hydrogen bonding helps miscibility
Other polar liquids are often miscible with water

129
Q

What is peculiar about ice in regards to density

A

Normally solids are denser than their liquids but ice floats on water

130
Q

Why does ice float on water

A

The intermolecular bonding associated with small covalent molecules is usually London dispersion forces of attraction.
In ice intermolecular forces of attraction is hydrogen bonding.
This results in a crystal lattice of water molecules are held together by network of hydrogen bonds
This arrangement not only makes the structure strong but it also speaks about the water molecules and so prevents them from packing closely together

131
Q

Ionic lattices and polar covalent compounds tend to be soluble in….

A

Water and other polar solvents due to the interaction of opposite charges

132
Q

Why is it that I wanna glasses and polar covalent compounds tend to be soluble in water and other polar solvents?

A

When I only compounds dissolved in water the lattice becomes surrounded by polar water molecules
The negative ions are attracted to the positive ends of the water molecules and the positive ions attracted to the negative end of the water molecule

133
Q

Ions surrounded by a layer of water molecules held by electrostatic forces of attraction are said to be

A

Hydrated

134
Q

Nonpolar molecules will tend to be soluble in…

A

Nonpolar solvents like hexane or carbon tetrachloride and insoluble in water and other polar solvents as they have no charged ends to be electrostatically attracted to the polar solvent molecules

135
Q

Describe covalent network structures

A

The structures have an infinite three-dimensional network structure of non-metal atoms bonded together by covalent bonds is elements of extremely high melting and boiling points
For example silicon dioxide and silicon carbide

136
Q

Name are used for silicon carbide

A

It is the hardest substance known to man and is used on abrasive wheels for cutting rocks or on grinders for sharpening metals

Higher Chemistry (4 decks)

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