Chemistry Paper 2 November 2018

1. Aisomers
2. Bisotopes
3. Callotropes
4. Disoelectronic ions

1. A79.0
2. B79.5
3. C80.0
4. D81.0

1. A$O^-(g) \rightarrow O(g) + e^-$
2. B$O^+(g) \rightarrow O^{2+}(g) + e^-$
3. C$O(g) + e^- \rightarrow O^-(g)$
4. D$O(g) \rightarrow O^{2+}(g) + 2e^-$

1. Athe mass of one atom of an element compared with the mass of one atom of hydrogen-1, ignoring how abundant each isotope actually is
2. Bthe total combined mass of every isotope of an element simply added together, without any weighting by natural abundance
3. Cthe mass number of only the single most abundant isotope of the element, ignoring all of its other isotopes entirely
4. Dthe weighted average mass of the isotopes of an element, relative to 1/12 the mass of a carbon-12 atom

1. Araising it, because the extra positive charge attracts the outer electron more strongly
2. Bleaving it completely unchanged, because nuclear charge is assumed to only ever affect the innermost core electrons in every case
3. Clowering it, because an increase in nuclear charge automatically increases the amount of electron shielding present as well
4. Dlowering it, because the extra protons in the nucleus repel the outer electrons away from each other repeatedly

1. Araising it, because the nucleus attracts the outer electron over a much longer range than before
2. Bleaving it completely unchanged, because atomic radius does not affect the attraction between the nucleus and the outer electron at all
3. Clowering it, because the outer electron is farther from the nucleus and less strongly attracted
4. Draising it, because a larger atom automatically has more shielding electrons surrounding its nucleus at all times

Answer this when you sit the paper.

1. Athe energy needed to melt one mole of the compound
2. Bthe energy needed to remove one mole of electrons from the bond
3. Cthe energy released when one mole of the bond is formed in solution
4. Dthe energy needed to break one mole of the bond in the gaseous state

1. A$-122$
2. B$-56$
3. C$+56$
4. D$+122$

1. Athe ionic charges decrease and the ionic radii decrease
2. Bthe ionic charges increase and the ionic radii decrease
3. Cthe ionic charges decrease and the ionic radii increase
4. Dthe ionic charges increase and the ionic radii increase

1. Aless soluble, because more energy is needed to separate the ions before they can be hydrated
2. Bmore soluble, because the ions separate from the lattice more easily than usual in this case
3. Cunaffected in solubility, since lattice enthalpy and solubility are considered to be completely unrelated properties
4. Dmore soluble, because a larger lattice enthalpy always favours the hydration of the separated ions

1. Amore energy is released when the gaseous ions are formed
2. Bthe lattice adopts a different, more stable crystal structure
3. Cthe electrostatic attraction between the ions is stronger
4. Dthe ions become larger, increasing surface contact

1. Athe ions somehow carry a higher electrical charge as a direct result of being smaller
2. Bthe ions are closer together, increasing the electrostatic attraction between them
3. Cthe ions pack less efficiently into the lattice, leaving larger empty gaps throughout the structure
4. Dthe lattice becomes covalent rather than ionic once the ions fall below a certain critical size

Answer this when you sit the paper.

1. A$2MgCO_3 \rightarrow Mg_2O + 2CO_2$
2. B$MgCO_3 \rightarrow Mg(OH)_2 + CO_2$
3. C$MgCO_3 \rightarrow MgO + CO_2$
4. D$MgCO_3 \rightarrow Mg + CO_2 + \frac{1}{2}O_2$

1. Aincreases, because the cation polarises the carbonate ion less
2. Bincreases, because the carbonates become more covalent
3. Cremains constant, because the charge on the cation is unchanged
4. Ddecreases, because the cations become larger

1. Amisty white fumes only
2. Ba green gas and a white precipitate
3. Creddish-brown fumes together with a pungent gas
4. Da violet vapour and a yellow solid

Answer this when you sit the paper.

Answer this when you sit the paper.

1. Aa green gas is evolved, accompanied by a strong smell of bleach throughout the flask
2. Ba violet vapour forms together with a yellow solid deposit around the neck of the flask
3. Csteamy, misty white fumes of hydrogen chloride are evolved
4. Da brown precipitate forms slowly, with no gas evolved at any point during the reaction

1. Achlorine gas produced in this reaction is colourless under all laboratory conditions and temperatures
2. Bchloride ions are not strong enough reducing agents to be oxidised by concentrated sulfuric acid
3. Csodium ions themselves are simply too large in radius ever to be oxidised by any common oxidising agent
4. Dhydrogen chloride gas is coloured only while it remains hot, becoming colourless again once it cools down

1. Apotassium cyanide in ethanol
2. Bacidified potassium dichromate(VI)
3. Caqueous sodium hydroxide
4. Dammonia in ethanol

1. Athe nitrogen atom carries a positive charge
2. Bthe molecule is smaller and more volatile
3. Cthe lone pair is delocalised over the carbon chain
4. Dthe alkyl group releases electrons, making the lone pair on nitrogen more available

1. Aacidic
2. Bneutral
3. Calkaline
4. Damphoteric

1. Aaqueous sodium hydroxide solution, heated strongly under reflux for several hours
2. Bconcentrated sulfuric acid, warmed gently in the presence of a small amount of water
3. Clithium tetrahydridoaluminate ($LiAlH_4$) in dry ether, or hydrogen with a nickel catalyst
4. Dacidified potassium dichromate(VI), heated gently under reflux for a considerable period of time

Answer this when you sit the paper.

1. Aa reduction reaction only, occurring with absolutely no change whatsoever in the total number of carbon atoms present
2. Bchain extension: a nucleophilic substitution that adds a carbon atom, followed by reduction of the nitrile to an amine
3. Can elimination reaction immediately followed by an addition polymerisation of the resulting alkene product
4. Da single-step hydrolysis reaction that converts the nitrile directly into a carboxylic acid product

Answer this when you sit the paper.

1. Athe solution turns green
2. Ba silver mirror forms
3. Can orange precipitate forms
4. Da white precipitate forms

1. Aa ketone
2. Ba diol
3. Can epoxide
4. Da carboxylic acid

1. Aa primary alcohol
2. Ban aldehyde
3. Can alkane
4. Da secondary alcohol

1. Aketone (carbonyl) group
2. Bhydroxyl group
3. Ccarbon-carbon double bond
4. Dester group

1. Athe double bond is somehow protected by the nearby hydroxyl group for the duration of the whole reaction
2. B$LiAlH_4$ only ever reacts with functional groups located at the very end of a carbon chain
3. Cthe double bond is simultaneously converted into a second alcohol group during the same reaction step
4. D$LiAlH_4$ reduces carbonyl groups but does not react with isolated carbon-carbon double bonds

1. Apolymerising the molecule through the double bond in a manner similar to how alkenes undergo addition polymerisation
2. Badding an $-OH$ group to each carbon atom of the double bond, forming a diol, exactly as the cold dilute reagent also does
3. Csimply reducing the double bond to a single bond, with absolutely no other observable change to the molecule
4. Dcleaving the double bond completely, oxidising each fragment to a carboxylic acid or a ketone depending on its substitution

1. Afractional distillation
2. Bsteam distillation
3. Cpaper chromatography
4. Dsolvent extraction

1. Aforms stronger intermolecular hydrogen bonds
2. Bis much more soluble in water
3. Chas a higher relative molecular mass
4. Dforms intramolecular hydrogen bonds and so is more volatile

1. Athe anaerobic decomposition of organic matter by bacteria
2. Bthe evaporation of petroleum residues
3. Cthe reaction of rainwater with buried metals
4. Dthe combustion of plastic waste

1. Arainwater percolates through decomposing waste, dissolving soluble and toxic substances
2. Bplastic waste slowly combusts underground due to the heat generated by decomposition nearby
3. Cburied metal objects react slowly with atmospheric oxygen that has seeped into the landfill
4. Dbacteria break down the organic waste in the total absence of air deep within the landfill

Answer this when you sit the paper.

Answer this when you sit the paper.

1. Aa steam-volatile compound to distil over at a temperature below its normal boiling point, avoiding decomposition
2. Bthe two isomers to react chemically together and then separate out as a single new compound entirely
3. Cboth compounds to boil simultaneously at their own separate normal boiling points, without any interference whatsoever
4. Dthe entire mixture to be distilled cleanly and completely without any water being present at any stage

1. Ais highly corrosive to metal structures and pipework located near the landfill site itself
2. Bdissolves readily in rainwater collecting nearby to form a dilute and highly localised acid rain
3. Cis a greenhouse gas that traps heat in the atmosphere, contributing to global warming
4. Ddepletes the ozone layer directly, allowing more harmful ultraviolet radiation to reach the ground

1. Aalkene, nitrile and carboxylic acid
2. Balkene, nitrile and ester
3. Calkene, amine and ester
4. Dalkyne, nitrile and ketone

1. Ahydrolysis
2. Boxidation
3. Ccondensation
4. Daddition

1. A$-[CH_2-C(CN)(COOCH_3)]-$
2. B$-[CH=C(CN)(COOCH_3)]-$
3. C$-[OCH_2-CO(CN)]-$
4. D$-[CH_2-CH(CN)]-$