|
Hint
|
|
Answer
|
|
nitrogen molecules are unreactive due to the strong ____ which must be broken before it can react
|
|
triple bond
|
|
ammonia has a ____ of electrons on the nitrogen
|
|
lone pair
|
|
ammonia can act as a base because it can form a ____ covalent bond with a hydrogen ion giving the ammonium ion
|
|
dative
|
|
nitrogen oxide is a ____ gas that turns to brown nitrogen dioxide in air
|
|
colourless
|
|
it comes from combustion processes, thunderstorms, and formation in the soil by ____
|
|
denitrifying bacteria
|
|
dinitrogen oxide is a colourless gas formed in the soil by ____
|
|
denitrifying bacteria
|
|
nitrogen dioxide is a brown gas formed by ____ of nitrogen oxide in the atmosphere
|
|
oxidation
|
|
when oxygen content is low, ____ bacteria reduce nitrate (V) ions to gaseous nitrogen
|
|
anaerobic
|
|
____- (aq) => NO2- (aq) => NO (g) => N2O (g) => N2 (g)
|
|
NO3
|
|
in nitrate (____) ions, one oxygen is bonded with a single bond and one with a double bond and there is a lone pair on the nitrogen
|
|
III
|
|
in nitrate (____) the nitrogen has also used the lone pair to form a dative covalent bond to an oxygen atom
|
|
V
|
|
nitrite and nitrate are both water soluble and are made through oxidation of ____ ions by aerobic bacteria in soil
|
|
ammonium
|
|
this is called ____ is carried out by the bacteria to obtain respiratory energy
|
|
nitrification
|
|
NH4+ (aq) + 1.5O2 (g) => ____- (aq) + 2H+ (aq) + H2O(l)
|
|
NO2
|
|
NO2- (aq) + 0.5O2 (g) => ____- (aq)
|
|
NO3
|
|
test for nitrate (V) ions: heat with sodium hydroxide and ____, ammonia gas will be evolved
|
|
Devarda's alloy
|
|
Devarda's alloy contains copper, ____ and zinc (____ is the reducing agent)
|
|
aluminium
|
|
3NO3- + 8Al + 5OH- => 3____ + 8[Al(OH)4]-
|
|
NH3
|
|
ammonia turns damp red litmus paper ____ and has a characteristic sharp choking smell
|
|
blue
|
|
to test for ammonium ions, heat gently with sodium hydroxide solution and ____ gas will be evolved
|
|
ammonia
|
|
NH4+ (aq) + OH- (aq) => NH3 (g) + ____ (l)
|
|
H2O
|
|
____ of reaction is measured as a change in property over time, e.g. volume of gas evolved, mass change, pH measurement, colorimetry, titration
|
|
rate
|
|
rate = k[A]^m[B]^m where k is the ____
|
|
rate constant
|
|
m and n are the powers to which the ____ need to be raised
|
|
concentrations
|
|
if i double concentration of reactant, and rate doubled, ____ = 1. if i double it and rate quadruples, ____ = 2
|
|
order of reaction
|
|
these are called order of reaction with ____ to A and B
|
|
respect
|
|
overall order of reaction = ____ + n
|
|
m
|
|
____ equation: k = Ae^(Ea/RT) or lnK = lnA - (Ea/RT)
|
|
Arrhenius
|
|
A is the ____ which is a representation of collision frequency and orientation of moelcules
|
|
frequency factor
|
|
to find order of reaction for a reactant you must make sure the only thing changing is the ____ of that reactant
|
|
concentration
|
|
e.g. by using a large ____ of a reactant so concentration does not significantly change
|
|
excess
|
|
a ____ shows how the concentration of a reactant or product changes over the course of a reaction
|
|
progress curve
|
|
finding the ____ for different concentrations lets you work out order of reaction
|
|
initial rate
|
|
e.g. by measuring the ____ time to produce a small, fixed amount of one of the products
|
|
reaction
|
|
you can use the progress curve to find ____ of a reaction - if ____ is constant, the reaction is first order
|
|
half life
|
|
the ____ is the slowest step in a reaction mechanism
|
|
rate determining step
|
|
the power of each substance in the rate equation corresponds to number of ____ of each substance in the rate determining step
|
|
molecules
|
|
some steps in a reaction are slower than others due to a larger ____
|
|
activation enthalpy
|
|
the ____ for a reaction involving two steps will have two activation energies
|
|
enthalpy profile
|
|
usually the ____ are at higher energy than the reactants and products because they have unusual structures or bonding
|
|
intermediates
|
|
chemical processes have various costs, e.g. the ____ to make the feedstock
|
|
raw materials
|
|
these usually have to be prepared or treated to ____ them and ensure they are present in the right proportions
|
|
purify
|
|
feedstock needs to be in an easy-to-handle form. transferring gases and liquids is done by ____
|
|
pipeline
|
|
cost of ____ may be high so number of pumps and length of piping is kept to a minimum
|
|
piping
|
|
____ are expensive to handle so are sometimes melted or made into a slurry to reduce transportation costs
|
|
solids
|
|
product: ____. feedstock: methane, air, water. raw materials: natural gas, air, water
|
|
ammonia
|
|
product: ____. feedstock: sulfur, air, water. raw materials: natural gas/oil (desulfurisation yields the sulfur), air, water
|
|
sulfuric acid
|
|
product: ____. feedstock: ammonia, air, water. raw materials: natural gas.oil, air
|
|
nitric acid
|
|
product: ____. feedstock: methanol, carbon monoxide, water. raw materials: coal/natural gas, air, water
|
|
ethanoic acid
|
|
natural gas is mostly methane but also contains ethane, propane and butane which are ____ cracked to produce ethene and propene
|
|
steam
|
|
distillation of ____ produces various fractions such as LPG, naphtha, and gas oil
|
|
crude oil
|
|
LPG
|
|
liquefied petroleum gas
|
|
LPG is steam cracked to form ____ and propene
|
|
ethene
|
|
naptha is steam cracked or can be reformed into ____ alkanes, cycloalkanes and aromatic hydrocarbons for high grade petrol
|
|
branched chain
|
|
gas oil is ____ cracked to ethene, propene and high grade petrol
|
|
catalytically
|
|
a second product that also has a commercial benefit
|
|
coproduct
|
|
ratio of product: coproduct is fixed and some reaction routes would be ____ if the coproduct could not be used
|
|
unprofitable
|
|
unwanted products produced from reactions
|
|
byproduct
|
|
a feedstock might: form one useful product, form two useful products, undergo a ____ and form byproducts, not react at all
|
|
side reaction
|
|
sales of product have to offset initial costs like research and development, ____ design and construction, and initial production
|
|
plant
|
|
costs incurred by the company irrespective of how much product is produced (e.g. labour costs, land rental, sales expenses, depreciation of the plant value)
|
|
fixed costs
|
|
costs that relate to the unit of production (e.g. raw materials, costs of effluent treatment and disposal, distributing the product)
|
|
variable costs
|
|
____ of a chemical process affects total costs
|
|
efficiency
|
|
necessary to balance rate, position of ____ and costs to get the greatest yield for money
|
|
equilibrium
|
|
you can reduce cost with use of an effective ____, recycling unreacted feedstock and selling coproduct
|
|
catalyst
|
|
chemical reactions can conserve ____ energy by lagging pipes (insulating them) and using a heat exchanger
|
|
thermal
|
|
heat exchanger: allows exothermic parts of the process to supply energy to ____ parts
|
|
endothermic
|
|
water and ____ can be used to transfer energy within a chemical plant - ____ produced in one process can be used in a different part of the plant
|
|
steam
|
|
____ include: flammable gases, acidic gases, toxic emissions, all of which must be managed and are legislated
|
|
hazards
|
|
manufacture also provides ____ such as biofuels, colorants, foodstuffs, paints, fertilisers, etc
|
|
benefits
|
|
molecule with two carboxyl groups has suffix ____ acid
|
|
dioic acid
|
|
carboxylic acids, phenols and alcohols form salts with metals in a ____ reaction
|
|
redox
|
|
to improve euilibrium ____ of esterification of an alcohol with a given amount of carboxylic acid, add excess alcohol or distill water as it is produced
|
|
yield
|
|
esters have ____ or fruity smells
|
|
floral
|
|
____ polymerisation: monomers react to give a larger chain polymer and a small stable molecule (usually water or HCl)
|
|
condensation
|
|
the -OH group in phenol is less ____ than in alcohol so does not esterify with carboxylic acids
|
|
reactive
|
|
amine structure resembles ____ in which alkyl groups replace one, two or three of the hydrogen atoms
|
|
ammonia
|
|
primary amine: one ____ group. secondary: two. tertiary: three
|
|
alkyl
|
|
amines with low molecular masses are gases or ____ liquids
|
|
volatile
|
|
the volatile amines have strong smells of ____
|
|
rotting fish
|
|
amines can form ____ bonds with water and become less soluble as the carbon chain gets longer and the amine group has less effect
|
|
hydrogen
|
|
solutions of amines are alkaline because they can be protonated by water, forming an ____ ion and hydroxide ion
|
|
alkylammonium
|
|
amines react with ____ to completion and the solution loses its strong smell
|
|
acids
|
|
primary ____ are derivatives of carboxylic acids made by replacing the -OH group with -NH2
|
|
amides
|
|
acyl ____ + ammonia -> primary amide + hydrochloric acid
|
|
chloride
|
|
acyl chloride + ____ -> secondary amide + hydrochloric acid
|
|
amine
|
|
diamines and dicarboxylic acids can be used to make a polymer (called polyamide or nylon) chain linked by ____ groups
|
|
amide
|
|
acyl chlorides react with alcohols to form ____
|
|
esters
|
|
esters and amides can be hydrolysed by addition of a ____ concentrated acid or alkali
|
|
moderately
|
|
____ + water + H+ => carboxylic acid + ammonium
|
|
primary amide
|
|
____ + water + H+ => carboxylic acid + amine salt
|
|
secondary amide
|
|
____ + water + OH- => carboxylate salt + ammonia
|
|
primary amide
|
|
____ + water + OH- => carboxylate salt + amine
|
|
secondary amide
|
|
____ contain at least one amino group and one carboxylic acid group
|
|
amino acids
|
|
compounds with 2 functional groups
|
|
bifunctional
|
|
ions with both negatively and positively charged groups
|
|
zwitterions
|
|
amino acids form zwitterions because the -COOH can donate a ____ to the -NH2
|
|
proton/H+
|
|
amino acids are water-soluble and usually ____ in solution
|
|
neutral
|
|
amino acids can ____ against pH changes due to the zwitterions so amino acids exist in 3 different ionic forms depending on pH of the solution
|
|
buffer
|
|
____ isomerism arises because the four single bonds around a carbon atom are arranged tetrahedrally
|
|
optical
|
|
non-superimposable mirror images
|
|
enantiomers/optical isomers
|
|
a carbon atom bonded to four different groups
|
|
chiral centre
|
|
molecules non-superimposable on their mirror images are ____
|
|
chiral
|
|
enantiomers share most chemical and physical properties but may behave differently in the presence of other ____ molecules and sometimes smell or taste different
|
|
chiral
|
|
a ____ link forms when 2 amino acids react to form a secondary amide group
|
|
peptide
|
|
amino aid which has lost the elements of water in forming a peptide
|
|
residue
|
|
there are ____ amino acids. you abbreviate them to their first three letters
|
|
20
|
|
you can ____ proteins by heating with moderately concentrated acid or alkali (catalysed by enzymes instead in living systems)
|
|
hydrolyse
|
|
____ can be used to identify the individual amino acids present in a peptide
|
|
paper chromatography
|
|
the peptide is hydrolysed under ____ and the product compared to known samples of pure amino acids using chromatography
|
|
reflux
|
|
sequence of amino acids, determines ultimate structure and thus function
|
|
primary structure
|
|
folding of the primary structure due to hydrogen bonding between the NN and C=O groups
|
|
secondary structure
|
|
further folding due to IDID bonds, hydrogen bonds between polar side chains, ionic bonds, and disulfide links
|
|
tertiary structure
|
|
____ proteins are fibrous and consist mainly of helices
|
|
structural
|
|
____ proteins are globular and have both sheets and helices
|
|
globular
|
|
where on the enzyme the substrate binds
|
|
active site
|
|
the bonds between enzyme and ____ are weak, and cause bonds within the ____ to be deformed or weaken
|
|
substrate
|
|
the reaction is ____ order with respect to the enzyme at low substrate concentrations and first order at high ones
|
|
zero
|
|
prevent substrates binding by binding to the active site and occupying it
|
|
inhibitors
|
|
hydrogen and IDID bonds are easily broken by ____ changes
|
|
temperature
|
|
pH changes alter the shape of the active site by interfering with the ____ groups
|
|
ionisable
|
|
the part of a medicine's molecule that gives a medicine its effect
|
|
pharmacophore
|
|
these can be modified by changing ____ to make the medicine more effective or reduce side effects
|
|
functional groups
|
|
they interact with receptor sites by forming weak interactions and can fit into receptor sites with the correct size, shape and ____
|
|
orientation
|
|
____ groups are H2PO4-
|
|
phosphate
|
|
DNA monomer: phosphate, sugar, nitrogenous base adenine, thymine, guanine or cytosine
|
|
nucleotide
|
|
deoxyribose is the sugar in DNA and ____ in RNA
|
|
ribose
|
|
____ pairs with thymine/uracil and forms 2 hydrogen bonds
|
|
adenine
|
|
____ pairs with guanine and forms 3 hydrogen bonds
|
|
cytosine
|
|
one strand can synthesise a ____ copy of itself prior to cell division
|
|
complementary
|
|
one strand can make a complementary copy of mRNA by ____
|
|
transcription
|
|
transcription: (1) a section of the DNA unzips by breaking the ____ bonds between strands
|
|
hydrogen
|
|
(2) RNA ____ pair to complementary bases and are joined using enzymes
|
|
nucleotides
|
|
(3) the double ____ reforms and the mRNA passes out of the nucleus
|
|
helix
|
|
each three bases, or ____, code for an amino acids
|
|
codons
|
|
the DNA code is ____ as some codons code for the same amino acid
|
|
degenerate
|
|
the start codon is ____ and the amino acid methionine is always at the start of the protein sequence (sometimes hydrolysed off later)
|
|
AUG
|
|
there are also three ____ (UAA, UGA, UAG) that end the synthesis
|
|
stop codons
|
|
translation: (1) mRNA attaches to the ____
|
|
ribosome
|
|
(2) tRNA with an attached amino acid binds to the mRNA by its complementary ____
|
|
anticodon
|
|
(3) amino acids held close together form ____
|
|
peptide links
|
|
a DNA segment that codes for a particular protein
|
|
gene
|
|
we sometimes use ____ mass spectrometry for molecules with similar Mr (accurate to 4dp)
|
|
high resolution
|
|
carbon-13 NMR and proton NMR are methods of nuclear magnetic resonance to determine number of carbon and hydrogen ____ and their properties
|
|
environments
|
|
JUST DO PRACTICE QUESTIONS ON USING INFRARED, MASS SPECTRA, C-13 AND H NMR IM NOT WRITING ALLAT IN HERE (type OK)
|
|
ok
|
|
the 4s subshell is usually filled before the 3d subshell except in ____ and copper
|
|
chromium
|
|
____ has an electron in each 3d sub shell and an electron in the 4s sub shell
|
|
chromium
|
|
____ has a full 3d sub shell and one electron in the 4s sub shell
|
|
copper
|
|
when transition metals form cations, they lose the ____ electrons first
|
|
4s
|
|
____ and scandium are not transition metals because their ions do not have incomplete 3d orbitals
|
|
zinc
|
|
iron content can be analysed using redox titration as iron (II) can be oxidised to iron (II) by ____ (VII) in solution
|
|
potassium manganate
|
|
the end point is where the first permanent ____ colour is observed because MnO4- is in excess
|
|
pink
|
|
in heterogeneous catalysis, transition metals can use the 3d and 4s electrons of atoms on the metal surface to form weak bonds to reactants - ____
|
|
chemisorption
|
|
in ____ catalysis, the transition metal usually forms an intermediate compound with 1+ reactants that breaks down to form the products
|
|
homogeneous
|
|
transition metals are particularly effective catalysts in redox reactions because they can move between ____ states
|
|
oxidation
|
|
Cu(OH)2 will give a a deep blue-purple solution on addition of excess ____ solution
|
|
ammonia
|
|
iron (II) hydroxide is a gelatinous green precipitate, iron (III) hydroxide gelatinous orange, neither form ____ with ammonia
|
|
complexes
|
|
____ surrounding a metal ion in solution causes d-orbital splitting
|
|
ligands
|
|
this means the difference between the two levels is such that the light absorbed falls in the ____ spectrum
|
|
visible
|
|
the ____ colour to the one absorbed will be seen
|
|
complementary
|
|
common ____ ligands are chloride, ammonia, cyanide and hydroxide
|
|
monodentate
|
|
colour of a transition metal ____ depends on number of d-electrons, arrangement of ligands, and the nature of the ligand
|
|
complex
|
|
in equations, charge, number of atoms and ____ state must all be balanced
|
|
oxidation
|
|
____ use redox reactions to generate electricity
|
|
electrochemical cells
|
|
electrical charge is measured in ____ and current is a measure of charge per second (measured in amperes)
|
|
coulombs
|
|
you can arrange for two half-reactions to occur simultaneously with ____ flowing through an external wire from one to the other
|
|
electrons
|
|
a ____ is used to determine potential difference between the half cells
|
|
high resistance voltmeter
|
|
to determine Ecell, measure the ____ potential difference between the terminals of the cell
|
|
positive
|
|
a ____ is used to balance the charges of the solutions without them mixing
|
|
salt bridge
|
|
a metal/metal ion half cell will use a ____ mol dm^-3 solution of ions and a metal electrode
|
|
1
|
|
an ion/other ion half cell will use a solution containing both ions and an inert ____ electrode
|
|
platinum
|
|
when two-half cells are placed together, the one with the more ____ potential will become the positive terminal of the cell
|
|
positive
|
|
a more positive Ecell indicates a greater tendency for ____
|
|
reduction
|
|
the ____ is the reference half-cell and is Ecell is defined as 0.0V
|
|
standard hydrogen half cell
|
|
this comprises of a 1 mol dm^-3 acid solution, ____ electrode, glass tube covering the electrode with holes to allow gas to escape, and hydrogen entering the tube at the top
|
|
platinum
|
|
the ____ of a half cell is the potential difference between the half cell and a standard hydrogen half cell
|
|
standard electrode potential
|
|
the ____ series is (from most negative to most positive standard electrode potential) is magnesium, zinc, hydrogen, copper, silver
|
|
electrochemical series
|
|
you can use electrode potentials to make predictions about the ____ of redox reactions under certain conditions
|
|
feasibility
|
|
a reaction may be feasible at standard conditions but slow if ____ is high
|
|
activation enthalpy
|
|
formation of iron (III) oxide by an electrochemical process
|
|
rusting
|
|
half reactions: (1) Fe2+ (aq) + 2e- <=> ____ (s)
|
|
Fe
|
|
(2) 0.5O2 (g) + H2O (l) + 2e- <=> 2____- (aq)
|
|
OH
|
|
oxygen is reduced to hydroxide ions and iron is oxidised to iron (II) ions because the oxygen/hydroxide half-cell has a more ____ electrode potential
|
|
positive
|
|
oxygen is reduced to hydroxide ions at the edges of the water droplet where oxygen ____ is high
|
|
concentration
|
|
the electrons needed for this come from the ____ of iron at the centre, where concentration of dissolved oxygen is low
|
|
oxidation
|
|
____ forms in a series of secondary processes within the solution as the Fe2+ ions and OH- ions diffuse away from the metal surface
|
|
rust
|
|
(1) Fe2+ (aq) + 2OH- (aq) => Fe(OH)2 (s) forms iron (II) ____
|
|
hydroxide
|
|
(2) Fe(OH)2 (s) => Fe2O3 • xH2O in the presence of dissolved ____
|
|
oxygen
|
|
the simplest way to protect steel from rust is with a ____ between the metal and atmosphere e.g. oil, grease, paint
|
|
barrier
|
|
any metal with a more negative Ecell than iron can be used as a ____ metal because it shifts the position of equilibrium to stop iron ions forming
|
|
sacrificial
|
|
e.g. ____ steel: covered with a layer of zinc - as long as this remains undamaged a protective metal oxide layer will form and protect the lower layer
|
|
galvanised
|
|
____ oxidation of a metal occurs at an anode site so any technique that makes a metal a cathode will prevent it from corrosion
|
|
destructive
|
|
another method of making it a cathode is by externally supplying ____ to it
|
|
electrons
|
|
the ____ terminal of a dc supply is connected to the metal - electrons flow from anode to cathode so this makes the metal a cathode
|
|
negative
|
|
the anode is usually an ____ electrode which is corrosion resistant
|
|
inert
|
|
rather than the anode, ____ is oxidised: 2H2O (l) => O2(g) + 4H+ (aq) + 4e-
|
|
water
|
|
a ____ consists of a central metal ion surrounded by ligands
|
|
complex
|
|
anions or neutral molecules with at least one lone pair of electrons
|
|
ligands
|
|
if a complex is charged, it is called a ____
|
|
complex ion
|
|
the overall ____ of a complex is the sum of the ____ on the metal ion and the charges on the ligands
|
|
charge
|
|
the charges on a complex ion are ____ over the whole ion
|
|
delocalised
|
|
ligands form a dative covalent bond (or ____ bond) with the metal, making the ligands Lewis bases
|
|
coordinate
|
|
number of bonds from the central ion to the ligands (usually 6 or 4)
|
|
coordination number
|
|
complexes with coordination number 6 are usually ____
|
|
octahedral
|
|
complexes with coordination number 4 are usually ____
|
|
tetrahedral
|
|
the ethanedioate is ____ because it can form two bonds with a metal ion
|
|
bidentate
|
|
ethanedioate structure: two connected -COO- groups, each O- has a ____ it uses to form the coordinate bond
|
|
lone pair
|
|
ligand ____ reactions can occur to replace one ligand with another
|
|
substitution
|
|
e.g. if you add concentrated ____ acid to a [Cu(H2O)6]2+ complex a [CuCl4]2- complex will form
|
|
hydrochloric
|
|
substitution occurs if the new complex is more ____ than the last
|
|
stable
|
|
iron 2+ and iron 3+ form complexes with water with coordination number ____
|
|
6
|
|
Cu 2+ forms complexes with water with coordination number 6 and complexes with ammonia and chloride with coordination number ____
|
|
4
|
|
the energy change when one mole of an ionic compound's crystal lattice forms from its constituent gaseous ions under standard conditions
|
|
lattice enthalpy
|
|
these are large ____ quantities that depend on size and charge of the ion
|
|
negative
|
|
to break down a lattice therefore a lot of energy is required, which tends to stop substances ____ unless the energy is paid back later
|
|
dissolving
|
|
lattice enthalpies become more negative when: ionic charges ____ and radii decrease
|
|
increase
|
|
many ionic substances form aqueous solutions because the charged ions can interact with the ____ on the water
|
|
dipoles
|
|
ions in solution are ____ either strongly or weakly depending on charge density
|
|
hydrated
|
|
the enthalpy change for the formation of an aqueous solution of ions from one mole of gaseous ions
|
|
enthalpy change of hydration
|
|
for this you can assume a very ____ solution where ion-ion interactions are negligible
|
|
dilute
|
|
general term for enthalpy change when dissolving in solvents other than water
|
|
enthalpy change of solvation
|
|
the difference between the enthalpy changes of hydration of the anion and cation and the lattice enthalpy gives this
|
|
enthalpy change of solution
|
|
an ____ cycle will represent this
|
|
enthalpy
|
|
ionic solids are not soluble in ____ solvents like hexane because the interactions between ions and solvent is weak
|
|
non polar
|
|
hot objects emit ____ - the hotter the object, the higher the energy
|
|
electromagnetic radiation
|
|
the Earth radiates mainly ____ radiation
|
|
infrared
|
|
the radiation from the Sun that reaches the atmosphere is mainly in the visible and ____ regions
|
|
ultraviolet/UV
|
|
part of this energy is ____ by the Earth and atmosphere, some reflected back into space
|
|
absorbed
|
|
average ____ of the Earth is constant when it radiates energy as fast as it absorbs it but this balance can be disturbed by changes to the quantities of atmospheric gases
|
|
temperature
|
|
carbon dioxide and methane are examples of ____ gases
|
|
greenhouse
|
|
greenhouse gases absorb some of the ____ radiation emitted by the Earth
|
|
infrared
|
|
(1) absorption of infrared increases ____ energy
|
|
vibrational
|
|
(2) this is transferred to other molecules in the air by ____ which increases their kinetic energy and the temperature of the air
|
|
collisions
|
|
(3) some infrared is re-emitted back towards Earth, some out towards space, and the overall effect is to trap some ____ that otherwise would have been lost
|
|
radiation
|
|
burning of ____ has led to increasing levels of greenhouse gases
|
|
fossil fuels
|
|
____ is the most abundant greenhouse gas but it only absorbs certain wavelengths of infrared radiation
|
|
water vapour
|
|
the wavelengths of infrared that water vapour doesn't absorb
|
|
IR window
|
|
carbon dioxide absorbs in the IR window so increased CO2 levels mean more radiation is being ____ across a greater range of wavelengths
|
|
absorbed
|
|
an acid and its deprotonated form are called a ____ acid-base pair because the ____ base can accept a proton and become the acid again
|
|
conjugate
|
|
pH = -log[ ____ ]
|
|
hydrogen ions/H+
|
|
strong acids ____ completely but weak acids do not
|
|
dissociate
|
|
to find pH of a weak acid, you must find Ka, the ____
|
|
acid dissociation constant
|
|
pKa = -log[ ____ ]
|
|
Ka
|
|
calculating pH of a strong alkali requires using ____ (the ionisation product of water)
|
|
Kw
|
|
____ = [H+][OH-]
|
|
Kw
|
|
____ resist changes in pH on additional of small quantities of acid or alkali
|
|
buffers
|
|
buffers are usually made from a weak acid or base and one of its ____
|
|
salts
|
|
you make two assumptions: (1) all the A- ions come from the ____ because the weak acid supplies very few A- ions
|
|
salt
|
|
(2) almost all the HA put in the ____ remain unchanged
|
|
buffer
|
|
Ka = [H+] [salt] / [ ____ ] for buffers
|
|
acid
|
|
a substance that dissolves only slightly in solvent
|
|
sparingly soluble
|
|
a sparingly soluble ionic solid in contact with a ____ solution of its ions is an example of a chemical equilibrium
|
|
saturated
|
|
solubility product ____ = [concentration of ion]^moles of ion x [concentration of other ion]^moles of other ion
|
|
Ksp
|
|
you can use Ksp to predict if a ____ will form: if the calculated value is greater than Ksp, the substance will precipitate out
|
|
precipitate
|
|
Ksp varies with ____
|
|
temperature
|
|
some spontaneous reactions are ____
|
|
endothermic
|
|
a measure of the number of ways that molecules and their associated energy can be arranged
|
|
entropy
|
|
units of entropy are ____ per Kelvin per mole
|
|
joules
|
|
for a reaction to be feasible, total entropy change to the system and surroundings must be greater than ____
|
|
0/zero
|
|
total ____ change = ____ change of the system - (enthalpy change/temperature)
|
|
entropy
|
|
the requirement for equilibrium is that total entropy change equals ____
|
|
zero/0
|
|
changes where total entropy change > 0 are feasible but may not be ____ if they have a large Ea
|
|
spontaneous
|
|
some organic molecules consist of a system of alternating single and double bonds called a ____ system
|
|
conjugated
|
|
the electrons in the p orbitals making up the pi bonds become ____ over all the atoms in the system
|
|
delocalised
|
|
these systems can include ____ from correctly oriented oxygen and nitrogen atoms
|
|
lone pairs
|
|
a ____ ring is an example of a delocalised system
|
|
benzene
|
|
delocalised systems with 5 pi bonds in the system are likely to absorb light in the ____ range and appear coloured
|
|
visible
|
|
the more electrons are delocalised, the smaller the energy gap, and the ____ the wavelengths of light absorbed
|
|
longer
|
|
the benzene ring is a regular, ____ hexagon with bond angles 120
|
|
planar
|
|
the p orbital electrons form a delocalised charge cloud above and below the ____ of the ring which increases stability
|
|
plane
|
|
the ____ model showed alternating single and double bonds but was disproved by thermochemical data
|
|
Kekulé
|
|
enthalpy of hydrogenation is less ____ than predicted (should be 3x cyclohexene)
|
|
exothermic
|
|
shows that the structure is more stable so less energy is ____ when it is hydrogenated
|
|
released
|
|
benzene reacts with ____ in an electrophilic substitution reaction
|
|
electrophiles
|
|
the benzene ring remains intact and a ____ ion is released
|
|
hydrogen
|
|
the reactions are relatively slow because the mechanism disrupts the conjugated system and a ____ is often required
|
|
catalyst
|
|
benzene reacts with liquid bromine in the presence of an ____ (III) bromide catalyst
|
|
iron
|
|
the electrophile is formed from Br2 and FeBr3 - produces ____+ and [FeBr4]-
|
|
Br
|
|
chlorination is similar except it uses an ____ (III) chloride catalyst
|
|
aluminium
|
|
these occur at room temperature but aluminium (III) chloride can only be used in ____ conditions
|
|
anhydrous
|
|
benzene + chloroethane + anhydrous aluminium chloride is a Friedel Crafts ____ and forms ethylbenzene + HCl
|
|
alkylation
|
|
benzene + ethanoyl chloride + anhydrous aluminium chloride is a Friedel Crafts ____ and forms phenylethanone + HCl
|
|
acylation
|
|
benzene reacts with a mixture of concentrated ____ acid and sulfuric acid (nitrating mixture)
|
|
nitric
|
|
if the temperature is kept below 55C the product is ____
|
|
nitrobenzene
|
|
the electrophile is the NO2+ ____
|
|
cation
|
|
HNO3 + 2H2SO4 -> NO2+ + 2HSO4- + H3O+ where the products are the ____
|
|
nitrating mixture
|
|
inserting nitro groups into a benzene ring that is part of a ____ will modify the wavelength of light absorbed
|
|
chromophore
|
|
the region within a molecule that absorbs visible light and is responsible for its colour
|
|
chromophore
|
|
heating benzene and concentrated sulfuric acid under ____ for several hours, benzenesulfonic acid is formed
|
|
reflux
|
|
the electrophile is SO3+ which carries a large partial ____ charge on the sulfur atom
|
|
positive
|
|
benzenesulfonic acid is a ____ acid and forms salts in alkaline solution
|
|
strong
|
|
sulfonation provides a way of forming more ____ derivatives of aromatic compounds
|
|
soluble
|
|
____ functional group is R1-N=N-R2
|
|
azo
|
|
azo compounds are formed from a reaction between a ____ and a coupling agent
|
|
diazonium salt
|
|
if the R groups are ____ groups then the azo compound is more stable than if they are alkyl groups
|
|
arene
|
|
this is because the -N=N- group is ____ by becoming part of the delocalised system involving the arene groups
|
|
stablises
|
|
this stability allows aromatic azo compounds to be used as ____
|
|
dyes
|
|
diazonium compounds contain the ____ group R-N+≡N
|
|
diazonium
|
|
diazonium salts are usually unstable because the diazonium group is easily lost, forming ____ gas
|
|
nitrogen
|
|
however, if the group is attached to a ____ ring, it is stable enough to be formed as an intermediate
|
|
benzene
|
|
these compounds are produced in solutions below ____ degrees C
|
|
5
|
|
(1) dissolve the aromatic amine in dilute ____
|
|
hydrochloric acid
|
|
(2) add a cold solution of sodium nitrate (III) formula: ____
|
|
NaNO2
|
|
this reaction is called ____
|
|
diazotisation
|
|
the reactant here is nitrous acid formula: ____ which reacts with the amine functional group
|
|
HNO2
|
|
in a ____ reaction, a diazonium compound acts as an electrophile and reacts with the benzene ring of a coupling agent
|
|
coupling
|
|
a compound containing a relatively reactive benzene ring, usually with a phenol or phenylamine
|
|
coupling agent
|
|
dyes with a negative charge when dissolved in water due to the presence of sulfonate groups
|
|
acid dyes
|
|
acid dyes are applied in acid conditions where ____ and protein fibres will have positive NH3+ groups
|
|
polyaide
|
|
using a metal ion to join dye to fabric by forming chelate complex ions
|
|
mordanting
|
|
fibre reactive dyes are formed by adding ____ groups to the dye molecule
|
|
reactive
|
|
these form ____ bonds with polymers that have OH or NH2 groups
|
|
covalent
|
|
if a dye is a linear molecule with several NH2 groups and the polymer has frequent OH groups the dye and fibre can ____ bond
|
|
hydrogen
|
|
if the dye is small and not very polar, and the polymer has no OH or NH groups, ____ bonds form
|
|
instantaneous dipole induced dipole
|
|
oils and fats are mostly esters of glycerol ( ____ ) with long chain carboxylic acids
|
|
propane 1,2,3-triol
|
|
glycerol has 3 alcohol groups so 3 carboxylic acids form ester links to form a ____
|
|
triester
|
|
the carboxylic (or ____) acids can be saturated or unsaturated
|
|
fatty
|
|
an oil or fat can be hydrolysed by heating with concentrated NaOH to give glycerol and the ____ salts of the acids
|
|
sodium
|
|
the free fatty acids are released from the sodium salts by adding a dilute ____ acid like HCl (aq)
|
|
mineral
|
|
gas-liquid chromatography uses (1) for mobile phase, an ____ carrier gas like nitrogen
|
|
unreactive
|
|
(2) for stationary phase, a small amount of liquid with a high boiling point held on a finely divided inert ____
|
|
porous support
|
|
the material is packed into a ____ which is coiled inside an oven
|
|
column
|
|
process: (1) the sample is injected into the ____ stream before it enters the column
|
|
gas
|
|
(2) the components of the mixture each have a different ____ for the stationary vs mobile phase
|
|
affinity
|
|
(3) compounds who more greatly favour the mobile phase emerge more quickly than those that ____ in the stationary phase
|
|
dissolve
|
|
the most ____ compounds usually emerge first
|
|
volatile
|
|
____ = [component in stationary phase] / [component in mobile phase]
|
|
partition coefficient
|
|
a detector on the ____ tube monitors the compounds coming out of the column
|
|
outlet
|
|
signals from the detector are plotted as a ____
|
|
chromatogram
|
|
the time a given compound is held in the column
|
|
retention time
|
|
a GLC instument must be ____ using samples of known compounds
|
|
calibrated
|
|
conditions such as temperature affect retention time so conditions must remain ____
|
|
constant
|
|
the area (or ____ if the peaks are very sharp) under each peak depends on the amount of compound present
|
|
height
|
|
aldehydes can be ____ but ketones cannot
|
|
oxidised
|
|
____ test: a mixture of ____ A and B is warmed in a water bath with the aldehyde, colour change from blue solution to brick red precipitate
|
|
Fehling's
|
|
Fehling's A contains the weak oxidising agent ____ 2+
|
|
copper/Cu
|
|
Fehling's B is an alkaline solution containing a ____ ligand
|
|
bidentate
|
|
the blue Cu2+ is reduced to Cu+ which are precipitate as copper (I) ____
|
|
oxide
|
|
____ reagent: silver mirror forms on the inner surface of the test tube
|
|
Tollen's
|
|
silver ions in the [Ag(NH3)2]+ ____ are reduced to elemental silver
|
|
complex
|
|
____ is used to reduce aldehydes and ketones back to alcohols
|
|
sodium tetrahydridoborate (III)
|
|
CN- from KCN can be added across the C=O bond in acidic conditions to form ____ (2-hydroxynitriles)
|
|
cyanohydrins
|
|
the cyanide ion is a ____ and is attracted to the partially positive carbon
|
|
nucleophile
|
|
a new C-C bond forms and a pair of electrons in the C=O bond move onto the oxygen atom giving it a ____ charge
|
|
negative
|
|
the new negative ion takes up a ____ from the solvent
|
|
proton
|
|
this is nucleophilic ____
|
|
addition
|
