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LC Chemistry > Mix > Flashcards

Mix Flashcards

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
Q

In a periodic table, does the atomic radius increase or decrease on going left to right across a period?

A

Decrease

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34
Q

In a periodic table, does the atomic radius increase or decrease on going down a group?

A

Increase

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35
Q

The first ionisation energy values increase going across a period because?

A

Of the increase in nuclear charge and the decrease in atomic radius

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36
Q

The first ionisation values decrease going down a group because?

A

Of the increase on atomic radius and the screening effect of the inner energy levels

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37
Q

Bohr’s theory of the hydrogen atom

A

The hydrogen electron is restricted to those regions of the atom that have certain energy values (energy levels)

38
Q

Louis de Broglie stated that…

A

Electrons, like light, have the properties of waves as well as of particles

39
Q

Water Crystallisation

A

Substances that contain molecules of water in definite proportions locked into a crystal structure

40
Q

Standard solution

A

One whose concentration is accurately known

41
Q

Primary standard

A

A substance used to make a standard solution direct/ very pure and stable

42
Q

Primary standard example..

A

Anhydrous sodium carbonate

43
Q

Percentage Yield

A

Actual Yield
————–✖️100
Theoritcal Yield

44
Q

A Bronsten/Lowery acid

A

A proton donor

45
Q

A Bronsten/Lowery base

A

Proton acceptor

46
Q

Arrhenius’ definition of an acid

A

Dissociates in water in to produce H+

47
Q

Arrhenius’ definition of a base

A

Dissociates in water to produce OH-

48
Q

A conjugate pair

A

Consists of an acid and a base that differ by one proton

49
Q

The shortcomings of Arrhenius’ theory

A

1) . Hydronium ions (H3O+) are formed, not H+

2) . Restricted to reactions in water

50
Q

aA + bB —-\ cC + dD
-—
What is Kc? (equilibrium constant)

A

Kc = {C}c {D}d
———–
{A}a {B}b

51
Q

If Kc is < 1 …

A

The concentration of the products is less than the reactants

52
Q

Factors that effect rate of reaction

A 
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
Q

The rate of a chemical reaction is

A

The change in concentration in unit time of any one reactant or product

54
Q

The instantaneous rate of reaction

A

Is the rate at a particular point int time during a reaction

55
Q

A heterogeneous catalyst

A

Is a catalyst in a different phase to the reactants

56
Q

A homogenous catalyst

A

Is in the same phase the reactants

57
Q

Autocatalysis

A

Occurs when a product of a reaction increases the rate of the reaction

58
Q

Activation energy

A

Is the minimum energy with which particles need to collide to cause a reaction

59
Q

What is the influence of temperature on reaction rate?

A

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
Q

Radioactivity

A

Is defined as the spontaneous breaking up of unstable nuclei accompanied by the emission of radiation

61
Q

Alpha particles are

A

Helium nuclei with a positive charge and little penetrating ability

62
Q

Beta particles are

A

Electrons with a negative charge and greater penetrating ability than alpha

63
Q

Gamma rays are

A

high energy electromagnetic radiation with power penetrating ability

64
Q

Difference between nuclear and chemical reactions?

A

Nuclear reactions :
➡️ new element may be formed
➡️ changes occur in the nucleus
➡️ no chemical bonds broken or formed

65
Q

The half-life of a radioactive isotope

A

Is the time taken for half of the atoms in a sample of the isotope to decay

66
Q

Electroplating

A

Is the coating of metal into the surface of another metal using electrolysis

67
Q

The valency of an element is

A

The Humber of bonds each atom of the element forms when it reacts

68
Q

A covalent bond is

A

Formed when two atoms share a pair if electrons

69
Q

A sigma bond

A

Is a covalent bond between two atoms formed by end- on overlapping of orbitals

70
Q

A pi bond

A

Is a covalent bond between two atoms formed by sideways overlapping of orbitals

71
Q

A polar covalent bond

A

Is a covalent bond in which there is unequal sharing of electrons

72
Q

Electronegativity

A

The relative attraction of an atom for shared pairs of electrons in a covalent bond

73
Q

Methyl orange (i) pH (ii) colour in acid (iii) colour in base

A

(i) 3-5 (ii) red (iii) yellow

74
Q

Litmus (i) pH (ii) colour in acid (iii) colour in base

A

(i) 5-8 (ii) red (iii) blue

75
Q

Phenolphthalein (i) pH (ii) colour in acid (iii) colour in base

A

(i) 8-10 (ii) colourless (iii) pink

76
Q

The biochemical oxygen demand

A

The amount of dissolved oxygen in ppm used up by a sample over a period of five days in the dark

77
Q

If the forward reaction is exothermic the Kc …

A

Decreases as the temp rises

78
Q

If the forward reaction is endothermic the Kc …

A

Increases as the temp rises

79
Q

The electron pair repulsion theory

A
  • 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
Q

The oxidation number

A

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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