Section 1: Principles of Chemistry Flashcards

1
Q

What is the definition of diffusion?

A

The net movement of particles from an area of higher concentration to an area of lower concentration

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2
Q

What increases the rate of diffusion?

A

Higher energy and lower mass of particles

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3
Q

Which two solutions are used in the experiment to test how density of particles affects rate of diffusion?

A

Hydrochloric acid (HCl) and ammonia solution (NH4)

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4
Q

Are ammonia particles heavier than hydrochloric acid particles?

A

no

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5
Q

What is the white substance formed when hydrochloric acid and ammonia react?

A

Ammonium chloride

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6
Q

In the experiment testing how the density of particles affects the rate of diffusion, does the white ring form closer to the hydrochloric acid or ammonia solution?

A

Hydrochloric acid

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7
Q

What is the experiment to show diffusion occurring in air?

A

Bromine in a gas jar

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8
Q

What is the definition of an atom?

A

the smallest particle of an element

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9
Q

What is the definition of a molecule?

A

Two or more non-metal atoms held together by covalent bonds

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10
Q

What is the definition of an element?

A

a pure substance made of only one kind of atom

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11
Q

what is the definition of a compound?

A

A substance containing two or more elements bonded together in a fixed ratio

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12
Q

what is the definition of a mixture?

A

a combination of two or more substances that are not chemically combined

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13
Q

what is filtering used to separate?

A

Insoluble particles from a liquid (e.g. sand from water)

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14
Q

What is evaporation used to separate?

A

Dissolved substances from a solution (e.g. salt from a salt solution)

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15
Q

What is simple distillation used to separate?

A

The liquid from a dissolved solid in a solution (e.g. water from a salt solution)

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16
Q

What is fractional distillation used to separate?

A

Liquids from a mix of liquids (e.g. alcohol from a mix of alcohol and water)

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17
Q

What is chromatography used to separate?

A

A mixture of soluble substances (e.g. the colours found in ink)

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18
Q

What is crystallisation used to separate?

A

Solids from a solution (when hot solution is left to stand, allowing crystals to form)

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19
Q

What do chromatographs show?

A

How many different substances in a substance and their relative solubility (the most soluble solvent will travel the furthest)

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20
Q

What is the relative charge of a proton?

A

+1

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21
Q

What is the relative mass of a proton?

A

1

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22
Q

what is the relative charge of an electron?

A

-1

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23
Q

what is the relative mass of an electron?

A

1/1840

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24
Q

what is the relative charge of a neutron?

A

0

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25
Q

what is the relative mass of a neutron?

A

1

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26
Q

what is found in an atoms central nucleus?

A

protons and neutrons

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27
Q

how many electrons are in the first shell?

A

2

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28
Q

how many electrons are in the second shell?

A

8

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29
Q

how many electrons are in the third shell?

A

8

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30
Q

where are electrons found in an atom?

A

orbiting the nucleus in shells

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31
Q

what is the definition of atomic number?

A

the number of protons in the nucleus of an atom

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32
Q

what is the definition of mass number?

A

the total number of protons and neutrons in the nucleus of an atom

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33
Q

what is the definition of an isotope?

A

atoms of the same element with a different number of neutrons

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34
Q

what is the definition of relative atomic mass (Ar)?

A

the average mass of the atoms of an element

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35
Q

How do you calculate the relative atomic mass?

A

∑(isotope mass x isotope abundance) ÷ 100

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36
Q

what is the periodic table?

A

an arrangement of elements in order of atomic number

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37
Q

What does a group in the periodic table tell you about the element?

A

The number of electrons in the element’s outer shell and the charge of the elements ion

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38
Q

What is the charge on an ion of an element in group 2?

A

+2

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39
Q

What is the charge on an ion of an element in group 7?

A

-1

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40
Q

What does a period in the periodic table tell you about the element?

A

The number of shells with electrons in and element has

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41
Q

what is formula mass?

A

the sum of the atomic masses of all the atoms in the compound

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42
Q

what are moles?

A

The Avogadro number of particles in a substance (represents the amount of substance)

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43
Q

what is the formula to calculate moles from mass and formula mass?

A

Moles = mass ÷ formula mass

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44
Q

What is the molar volume of gas?

A

24 dm3 or 24,000 cm3

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45
Q

what is the formula to calculate moles from volume?

A

Moles = volume ÷ 24dm3

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46
Q

What is the state symbol for solids?

A

(s)

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47
Q

what is the state symbol for liquids?

A

(l)

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48
Q

what is the state symbol for gases?

A

(g)

49
Q

what is the state symbol for aqueous solutions?

A

(aq)

50
Q

How do you calculate the formula of a hydrated substance?

A
  1. Work out formula (using x to represent the number of water molecules)
  2. Work out mass of water and mass of substance (weigh before and after heating)
  3. Use formula to calculate moles
  4. Work out simplest ration by dividing both numbers by the smallest
51
Q

what is the empirical formula?

A

The simplest whole number ratio of atoms of each element present in a compound

52
Q

How do you work out empirical formula?

A
  1. Divide mass of substances by relative atomic mass for each substance
  2. Simplify ratio by dividing each number by the smallest one
53
Q

what is the formula for working out molecular formula from molecular formula mass and empirical formula?

A

(Molecular FM ÷ empirical FM) x empirical formula

54
Q

How do you calculate reacting masses?

A
  1. Work out moles of substance whose mass has been given
  2. Work out moles of other substance using ratio of the two
  3. Calculate mass of other substance by multiplying moles by FM
55
Q

what is the formula for calculating the percentage yield?

A

(Actual amount of product produced ÷ theoretical amount of product produced) x 100%

56
Q

what is the formula for calculating moles using volume and concentration?

A

Moles = volume (dm3) x concentration (mol/dm3)

57
Q

what is oxidation (in the context of electrons)?

A

loss of electrons (OIL)

58
Q

what is reduction (in the context of electrons)?

A

gain of electrons (RIG)

59
Q

nitrate ion

A

NO₃¹⁻

60
Q

sulfate ion

A

SO₄²⁻

61
Q

carbonate ion

A

CO₃²⁻

62
Q

hydrogen carbonate ion

A

HCO₃¹⁻

63
Q

hydroxide ion

A

OH¹⁻

64
Q

phosphate ion

A

PO₄³⁻

65
Q

ammonium ion

A

NH₄¹⁺

66
Q

silver ion

A

Ag¹⁺

67
Q

zinc ion

A

Zn²⁺

68
Q

lead ion

A

Pb²⁺

69
Q

aluminium ion

A

Al³⁺

70
Q

what is an ionic bond?

A

the strong electrostatic attraction between oppositely charged ions

71
Q

Why do ionic compounds have high melting and boiling points?

A

A lot of energy is required to break the strong ionic bonds between particles

72
Q

How does charge affect the melting/ boiling point of an ionic compound?

A

The greater the charge, the greater the electrostatic attraction, the stronger the ionic bond, the more energy required to break that bond, the higher the melting/ boiling point

73
Q

Why are ionic compounds soluble in water?

A

Water is polar molecule so the positive side attracts the negative ions and vice versa, breaking up the ionic lattice

74
Q

Why don’t ionic compounds conduct electricity?

A

When the ions are locked into a lattice the cannot move and carry charge

75
Q

Why do ionic compounds conduct electricity when molten or dissolved?

A

The ionic lattice is broken up so the ions can flow and carry charge

76
Q

Why are ionic compounds brittle?

A

If like charges are forced together they are repelled away from each other

77
Q

what is an ionic crystal?

A

A giant 3D lattice structure held together by the attraction between oppositely charged ions

78
Q

How are covalent bonds formed?

A

by the sharing of electrons between two atoms

79
Q

what is a covalent bond?

A

A strong electrostatic attraction between the binding pair of electrons and the nuclei of the atoms involved in the bond

80
Q

what can simple molecular structures be?

A

Non-metal elements (e.g. oxygen)
Non-metal compounds (e.g. carbon dioxide)
Carbon in the form of Buckminster Fullerene

81
Q

Why do simple molecular structure have low melting and boiling points?

A

They have relatively weak inter-molecular forces which do not require much energy to be overcome/broken

82
Q

Why don’t simple molecular structures conduct electricity?

A

they don’t have an overall charge

83
Q

what are allotropes?

A

the same elements with different molecular structures

84
Q

Why do giant covalent structure have high melting points?

A

A large amount of energy is required to break the strong covalent bonds

85
Q

Why are giant covalent structures insoluble?

A

In order to dissolve the structure would have to be broken up and the covalent bonds require too much energy to be broken

86
Q

Why don’t giant covalent structures conduct electricity?

A

The electrons in the outer shell are held tightly in covalent bonds so are not free to move and carry charge

87
Q

What is diamond used for?

A

Used for cutting as it is very hard due to the strong covalent bonds

88
Q

Why does graphite conduct electricity?

A

The delocalised electrons can flow and carry charge

89
Q

What is graphite used for?

A

As a lubricant because the attraction between each layer of graphite is relatively weak so can easily be flaked off

90
Q

what is a metal structure?

A

A giant structure of positive ions surrounded by a sea of delocalised electrons

91
Q

Why can metals conduct electricity?

A

Delocalised electrons can flow and carry charge

92
Q

Why are metals malleable?

A

Layers of positive ions can slide over one another

93
Q

Why do metals have high melting and boiling points?

A

Strong electrostatic forces require a lot of energy to be broken

94
Q

what is a metallic bond?

A

Strong electrostatic attraction between positively charged ions and the delocalised electrons

95
Q

what is electric current?

A

the flow of charged particles (ions or electrons)

96
Q

what is an electrolyte?

A

a substance that undergoes electrolysis (always contains ion)

97
Q

is an anode positive or negative?

A

positive

98
Q

is a cathode positive or negative?

A

negative

99
Q

are anions negative or positive?

A

negative

100
Q

are cations negative or positive?

A

paw-sitive

101
Q

do anions flow to the cathode or anode?

A

anode

102
Q

at the anode if the ion is a halogen what is formed?

A

the halogen

103
Q

At the anode if the ion is not a halogen what is formed?

A

Oxygen from OH- ions

104
Q

what is the ionic half equation for the formation of oxygen from hydroxide ions?

A

4OH- —> 2H2O + O2 + 4e-

105
Q

What is formed at the cathode if the cation is more reactive than hydrogen?

A

hydrogen gas

106
Q

What is formed at the cathode if the cation is less reactive than hydrogen?

A

The metal (copper/silver/gold) is formed

107
Q

What three metals are less reactive than hydrogen?

A

Copper, silver, gold

108
Q

What does one faraday represent?

A

The charge on one mole of electrons (96,500c)

109
Q

Describe how crystallisation can be used to obtain a pure dry sample of a salt

A

1) heat solution until crystals start to form
2) allow to cool/crystallise
3) filter and wash with water
4) leave to dry

110
Q

Explain how particle theory can be used to explain brown colour filling a gas jar with liquid bromine at the bottom

A

1) the bromine liquid evaporates

2) bromine has fills the gas jar because the gas particles move randomly

111
Q

What colour is magnesium oxide?

A

White

112
Q

What colour is copper oxide?

A

Black

113
Q

What does cobalt chloride do in the presence of water?

A

Turns from blue to pink

114
Q

Why is the solvent level in chromatography experiments below the base line?

A

To prevent ink spots dissolving in the solvent

115
Q

explain in terms of its structure why graphite can act as a lubricant

A

1) layers can slide over each other

2) weak intermolecular forces of attraction between layers

116
Q

explain why buckminsterfullerene has a much lower melting point than diamond

A

1) Not a giant structure
2) Weak intermolecular forces of attraction
3) No covalent bonds break when melting

117
Q

what is electrolysis?

A

the decomposition of a molten or aqueous ionic substance by electricity

118
Q

suggest why, in an electrolysis when the copper electrodes take part in the reaction, the increase in mass of the negative electrode is less than expected

A

1) some copper did not stick to negative electrode/cathode
2) some copper removed during washing/drying
3) positive electrode/anode impure