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Key Chemistry Defintions Flashcards

1
Q

Relative atomic mass

A

The average mass of an atom of an element, relative to 1/12th of the mass of an atom of carbon-12

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2
Q

Relative molecular mass

A

Average mass of a molecule compared to 1/12th of the mass of a carbon-12 atom

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3
Q

The avogradro constant

A

The number of particles in a mole

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4
Q

Ideal gas equation

A

pV = nRT

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5
Q

Empirical formula

A

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

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6
Q

Percentage atom economy

A

(Mass of desired product/total mass of reactants) x 100

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7
Q

Ionic bonding

A

The electrostatic attraction between oppositely charged ions in a lattice

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8
Q

Covalent bond

A

A shared pair of electrons between non-metal elements

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9
Q

Co-ordinate bond

A

A shared pair of electrons where both electrons are supplied by one atom

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10
Q

Repulsion in shapes of molecules

A

Lone pair-lone pair > lone pair-bonding pair > bonding pair-bonding pair

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11
Q

Electronegativity

A

The tendency of an atom to attract the pair of electrons in a covalent bond

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12
Q

Hess’s law

A

Total enthalpy change for a reaction is independent of the route chosen

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13
Q

Mean bond enthalpy

A

The energy required to break a covalent bond into gaseous atoms averaged over different molecules

Bonds broken - bonds made

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14
Q

Activation energy

A

The minimum amount of energy needed to start a chemical reaction

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15
Q

Catalyst

A

A substance that increases the rate of a chemical reaction without being changed by providing an alternative reaction pathway by lowering activation energy

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16
Q

Le chatelier’s principle

A

When a system in dynamic equilibrium is subjected to change, the position of equilibrium will shift to oppose the change

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17
Q

Oxidising agents

A

Electrons acceptors

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18
Q

Reducing agents

A

Electron donors

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19
Q

Enthalpy of formation

A

Enthalpy change when one mole of a compound is formed from its constituent elements under standard conditions in their standard states

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20
Q

Enthalpy of atomisation

A

The energy required to produce one mole of gaseous atoms from an element in its standard state

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21
Q

Electron affinity

A

The enthalpy change when one mole of gaseous atoms forms one mole of -1 ions

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22
Q

Lattice enthalpy of formation

A

Enthalpy change when one mole of a solid ionic compound is formed from its constituent ions in the gas phase

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23
Q

Lattice enthalpy of dissociation

A

Energy change when 1 mol of an ionic lattice dissociates to its gaseous ions

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24
Q

Standard electrode potential

A

298K
100kPa
1.0o moldm-3

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25
Electrode reactions with lithium cell (positive electrode)
Li+ + CoO2 + e- —> Li+[CoO2]-
26
Electrode reactions in lithium cell (negative electrode)
Li —> Li+ + e-
27
Electrode reactions in hydrogen-oxygen fuel cell in acidic conditions (positive electode)
O2 + 4H+ + 4e- —> 2H2O
28
Electrode reactions in hydrogen-oxygen fuel cell in acidic conditions (negative electrode)
H2 —> 2H+ + 2e-
29
Brosted- Lowry acid
Proton donor
30
Brosted- Lowry base
Proton acceptor
31
Weak acids
Partially dissociate in aqueous solution
32
What is an acidic buffer made of?
Weak acid and its salt
33
What is a basic buffer made of?
Weak base and its salt
34
Spontaneous reactions
When enthalpy is negative and entropy is positive (spontaneous at all temps) When enthalpy is positive and entropy is negative (not spontaneous at any temp )
35
Stereoisomerism
Molecules with the same structural and molecular formula but have a different spatial arrangement
36
Enthalpy change
Heat energy change at constant pressure
37
Oxidation of primary alcohols
Aldehyde (Alcohol in excess + product distilled off immediately) Carboxylic acid (oxidising agent in excess + under reflux)
38
Oxidation of secondary alcohols
Ketones No further oxidation
39
Oxidation of tertiary alcohols
Can’t be easily oxidised as they do not have 2 hydrogen atoms directly attached to the carbon that’s bonded to the OH group but can be oxidised by hot nitric acid
40
Oxidising agent for oxidation of alcohols
Acidified potassium dichromate Orange (Cr2O7-) to green (Cr 3+)
41
What happens when an unsymmetrical alcohol undergoes an elimination reaction
A mixture of isomeric products are produced
42
Biofuel
Any fuel made from living organisms or their waste
43
Carbon neutral
No net annual emissions of carbon dioxide into the atmosphere
44
Molecular ion (a molecule which has lost an electron)
Line with largest m/z ratio on a mass spectrum of a compound.
45
High resolution spectrometry
Used to distinguish between compounds and can measure relative atomic masses to 4 d.p
46
Finger print region
The area of the spectrum below the 1500cm-1, its unique to the molecule
47
Molecular formula
The actual number of atoms of each element in a compound
48
Functional group isomer
Compounds with the same molecular formula but different functional group
49
Positional isomer
Isomers with the same carbon chain and the same functional group but attached at different points of the carbon chain
50
Specific heat capacity
Energy required to raise the temperature of 1g of a substance by 1 degrees
51
Solvents used for nmr
CCL4, CDCL3 Do not cause peak on H nmr but causes known peak on carbon nmr
52
Carboxylic acid + carbonates
Salt, carbon dioxide + water
53
Carboxylic acid + alcohol
Ester + water
54
Uses for esters
Food colouring, perfumes, solvents and plasticisers
55
Uses for sulfur dioxide
Bleach, food preservatives
56
Acid hydrolysis for esters
Acid and alcohol
57
Base hydrolysis of esters
Carboxylate ion and alcohol
58
Hydrolysis of oils and fats using NaOH
Glycerol, soap (salt if long chain carboxylic acid)
59
How are biodiesel made
Reacting vegetable oils with methanol and KOH Makes glycerol and methyl esters
60
Uses for quaternary ammonium salts
Fabric cleaners, hair products
61
Enthalpy of hydration
Enthalpy change when 1 mole of gaseous ions becomes aqueous ions
62
Initial rate of reaction
The rate of reaction at time t = 0s. Used to compare the effect on the rate of changing the independent variable.
63
Rate determining step
The slowest step in a reaction mechanism
64
Equivalence point
The point during a titration when the number of H+ ions and OH- ions are equal. This is at the middle of the steepest part of the titration curve.
65
Buffer
A solution that resists changes in pH when small amounts of acid or base are added
66
Autocatalyst
Catalyst that is a reaction product
67
Transition metals
Elements that form coloured ions in solution and have multiple oxidation states
68
Ligand
An ion or molecule with at least one lone pair of electrons that can form a coordinate bond to a metal atom/ion
69
Complex
A central metal ion or atom surrounded by ligands
70
Co-ordination number
Number of lone pairs bonded to the metal ion
71
Haemoglobin
Protein structure containing four harm groups bonded to 4 globular proteins - used for gas exchange
72
Chiral carbon
A carbon atom attached to four different atoms or groups of atoms
73
Heterogenous catalyst
A catalyst that is in a different phase from that of the reactant substances
74
Homogenous catalyst
A catalyst that is in the same phase as all the reactants and products in a reaction system
75
Enantiomers
Non-superimposable mirror images
76
Racemic mixture
50/50 mixture of left and right enantiomers
77
Immiscible
Liquids that are not soluble in each other
78
Condensation polymers
Polymers formed from when monomers join together and eliminate a small molecule such as water or hydrogen chloride
79
Addition polymers
Polymers made from alkenes in an addition reaction
80
Zwitterion
Dipolar ion formed when amino acids undergo an internal acid-base reaction
81
Mobile phase
From chromatography, the liquid or gas used to move the sample up the stationary phase
82
Stationary phase
The phase that does not move in chromatography
83
Perfect ionic model
Ions which are perfect spheres with no covalent character
84
Isotopes
Atoms with the same number of protons but different number of neutrons
85
Alkali
A soluble base
86
First ionisation energy
The enthalpy change when one mole of electrons is removed from one mole of gaseous atoms to form one moles of gaseous ions with a single positive charge
87
Dative covalent bond
When an electron pair donated by one molecule is shared between two molecules
88
Activation energy
The minimum amount of energy required to start a chemical reaction
89
Disproportionation
When a substance is oxidised and reduced in a reaction to produce two different products
90
Anion
A negatively charged ion
91
Cation
A positively charged ion
92
Atom economy
Molecular mass of the desire product/sum of the molecular masses of all reactants x 100
93
Dynamic equilibrium
A equilibrium where both the forward and reverse reactions occurring at the same rate and the conc of the reactants and products remain constant
94
Enthalpy of combustion
Enthalpy change when one mole of a substance is burned completely in excess oxygen with all reactants and products in their standard states under standard conditions
95
Homologous series
Series of compounds with the same general formula
96
Percentage yield
Actual yield/theoretical yield x100
97
Reflux
The continuous boiling and condensing of a mixture
98
Structural isomerism
Compounds that have the same molecular formula but different structural formula
99
Concordant results in titrations
Similar results to the nearest 0.1cm3
100
Van der waals forces
Slight attraction that develops between oppositely charged regions of nearby molecules
101
Exothermic
Chemical reaction in which energy is primarily given off in the form of heat
102
Endothermic
Occurring or formed with absorption of heat
103
Rate of reaction
The speed at which a chemical reaction proceeds
104
Redox reaction
An oxidation reaction paired with a reduction reaction
105
Saturated
Fats with a maximum number of hydrogens
106
Unsaturated
Fats with less than the maximum number of hydrogens in one or more of its fatty acid chains
107
Polymer
Large compounds formed from combinations of many monomers
108
Monomer
A simple compound whose molecules can join together to form polymers
109
Chain isomer
Different ways of arranging a carbon chain
110
Hydrogen bond
Weak attraction between a hydrogen atom and another atom
111
Bond dissociation energy
The energy required to break the bond between 2 covalently bonded atoms
112
Enthalpy change of atomisation
The enthalpy change for the formation of one moles of gaseous atoms from the elements in its standard state
113
Enthalpy change of solution
The enthalpy change when one molecule of solute dissolves in water
114
Isoelectronic
Particles with the same electron configuration
115
Electrode reactions in hydrogen-oxygen fuel cell in alkaline conditions (positive electrode)
O2 + 2H2O + 4e- —> 4OH-
116
Electrode reactions in hydrogen-oxygen fuel cell in alkaline conditions (negative electrode)
H2 + 2OH- —> 2H2O + 2e-
117
Ethanol fuel cell (positive electrode)
12H+ + 3O2 + 12e- —> 6H2O
118
Define the term enthalpy change
The heat absorbed or released during a chemical reaction at constant pressure

physical chemistry (3 decks)

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