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0
Q

Chemical equilibrium is said to be dynamic because…

A

At equilibrium there are reactions continually occurring and the rate of the forward reaction equals the rate of the reverse reaction

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1
Q

Reversible reaction

A

Takes place in either direction

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2
Q

Balanced equation for the formation of ammonia

A

N2 +3H2 —-> 2NH3

<—-

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3
Q

Le chatelier’s principle

A

When a system at equilibrium is subjected to a stress, the equilibrium shifts in such a way as to minimise the effect of the stress

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4
Q

Equation for the reversible reaction between cobalt chloride and water

A

CoCl4 -2 + 6H2O –> Co(H2O) +
<–
4Cl-

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5
Q

The contact process

A

Process used to make sulfur trioxide

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6
Q

The Haber process

A

Process used to make ammonia

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7
Q

Rate of a chemical reaction

A

The change on concentration in unit time if any one reactant or product

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8
Q

Catalyst

A

A substance that alters the rate of a reaction but is chemically unchanged at the end of the reaction

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18
Q

Energy Level

A

A region of definite energy within an atom that electrons can occupy

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19
Q

Line Spectrum

A

A series of coloured lines against a dark background

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20
Q

The emission spectrum of an element

A

is characteristic of that element, and is different from that of any other element

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21
Q

The absorption spectrum of an element

A

The spectrum observed after white light has been passed through the element

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22
Q

The Heisenberg Uncertainty Principle

A

States that it is not possible to determine at the same time the exact position and velocity of an electron

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23
Q

An Atomic Orbital

A

A region in space where there is a high probability of finding an electron

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24
Q

The Aufbau Principle

A

States that electrons will occupy the lowest energy level available

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25
Q

An Energy Sub-level

A

A group of atomic orbitals within an atom all of which have the same energy

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26
Q

Potassium electron confirguration? How many

(i) energy levels (ii) energy sub-levels
(iii) individual orbitals

A 
1s2
2s2 2p6 
3s2 3p6
4s1  
Energy levels = 3 energy sublevels = 6 Orbitals = 10
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27
Q

Which is the energy level, energy sublevel and atomic orbital?
3px2

A

Energy level is the number in front (3)
Energy sub-level is the part of the letter
(X)
Atomic orbital is the entire letter group
(P group)

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28
Q

Ionisation Energy

A

A measure of the amount of energy needed to remove electrons from atoms

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29
Q

The First Ionisation Energy

A

The energy required to remove the most loosely bound electron from one mole of gaseous atoms in its ground state

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30
Q

The Second Ionisation Energy

A

The energy required to remove the most loosely bound electron from each singly charged positive ion in a mole of these ions

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31
Q

The Atomic Radius of an element

A

Half the distance between the nuclei of two atoms of the element that are joined together by a single covalent bond

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32
Q

Factors that affect the size of the atomic radius

A

Nuclear charge, number of energy levels and the screening effect of the inner electrons

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33
In a periodic table, does the atomic radius increase or decrease on going left to right across a period?
Decrease
34
In a periodic table, does the atomic radius increase or decrease on going down a group?
Increase
35
The first ionisation energy values increase going across a period because?
Of the increase in nuclear charge and the decrease in atomic radius
36
The first ionisation values decrease going down a group because?
Of the increase on atomic radius and the screening effect of the inner energy levels
37
Bohr's theory of the hydrogen atom
The hydrogen electron is restricted to those regions of the atom that have certain energy values (energy levels)
38
Louis de Broglie stated that...
Electrons, like light, have the properties of waves as well as of particles
39
Water Crystallisation
Substances that contain molecules of water in definite proportions locked into a crystal structure
40
Standard solution
One whose concentration is accurately known
41
Primary standard
A substance used to make a standard solution direct/ very pure and stable
42
Primary standard example..
Anhydrous sodium carbonate
43
Percentage Yield
Actual Yield --------------✖️100 Theoritcal Yield
44
A Bronsten/Lowery acid
A proton donor
45
A Bronsten/Lowery base
Proton acceptor
46
Arrhenius' definition of an acid
Dissociates in water in to produce H+
47
Arrhenius' definition of a base
Dissociates in water to produce OH-
48
A conjugate pair
Consists of an acid and a base that differ by one proton
49
The shortcomings of Arrhenius' theory
1) . Hydronium ions (H3O+) are formed, not H+ | 2) . Restricted to reactions in water
50
aA + bB ----\ cC + dD \---- What is Kc? (equilibrium constant)
Kc = {C}c {D}d ----------- {A}a {B}b
51
If Kc is < 1 ...
The concentration of the products is less than the reactants
52
Factors that effect rate of reaction
``` Catalysts (speeds up reaction), concentration (more particles bump into each other more frequently), temperature (particles more energised), surface area (increase surface area for reaction) ```
53
The rate of a chemical reaction is
The change in concentration in unit time of any one reactant or product
54
The instantaneous rate of reaction
Is the rate at a particular point int time during a reaction
55
A heterogeneous catalyst
Is a catalyst in a different phase to the reactants
56
A homogenous catalyst
Is in the same phase the reactants
57
Autocatalysis
Occurs when a product of a reaction increases the rate of the reaction
58
Activation energy
Is the minimum energy with which particles need to collide to cause a reaction
59
What is the influence of temperature on reaction rate?
The higher the temp., the greater the molecules have and the greater their average speed. This has two effects: (a) the number of collisions per second is increased (b) each collision is more energetic and a higher amount of collisions have the necessary activation energy for reaction to occur
60
Radioactivity
Is defined as the spontaneous breaking up of unstable nuclei accompanied by the emission of radiation
61
Alpha particles are
Helium nuclei with a positive charge and little penetrating ability
62
Beta particles are
Electrons with a negative charge and greater penetrating ability than alpha
63
Gamma rays are
high energy electromagnetic radiation with power penetrating ability
64
Difference between nuclear and chemical reactions?
Nuclear reactions : ➡️ new element may be formed ➡️ changes occur in the nucleus ➡️ no chemical bonds broken or formed
65
The half-life of a radioactive isotope
Is the time taken for half of the atoms in a sample of the isotope to decay
66
Electroplating
Is the coating of metal into the surface of another metal using electrolysis
67
The valency of an element is
The Humber of bonds each atom of the element forms when it reacts
68
A covalent bond is
Formed when two atoms share a pair if electrons
69
A sigma bond
Is a covalent bond between two atoms formed by end- on overlapping of orbitals
70
A pi bond
Is a covalent bond between two atoms formed by sideways overlapping of orbitals
71
A polar covalent bond
Is a covalent bond in which there is unequal sharing of electrons
72
Electronegativity
The relative attraction of an atom for shared pairs of electrons in a covalent bond
73
Methyl orange (i) pH (ii) colour in acid (iii) colour in base
(i) 3-5 (ii) red (iii) yellow
74
Litmus (i) pH (ii) colour in acid (iii) colour in base
(i) 5-8 (ii) red (iii) blue
75
Phenolphthalein (i) pH (ii) colour in acid (iii) colour in base
(i) 8-10 (ii) colourless (iii) pink
76
The biochemical oxygen demand
The amount of dissolved oxygen in ppm used up by a sample over a period of five days in the dark
77
If the forward reaction is exothermic the Kc ...
Decreases as the temp rises
78
If the forward reaction is endothermic the Kc ...
Increases as the temp rises
79
The electron pair repulsion theory
- The electron pairs in the outer shell of the central atom repel each other and end up as far apart as geometrically possible - Lone pairs have a greater repelling power than bond pairs
80
The oxidation number
The charge that the atom appears to have when the electrons are distributed according to certain rules

LC Chemistry (3 decks)

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