AQA AS Chemistry C12 The Alkanes Kerboodle Answer

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C12.1 Alkanes AQA AS Chemistry C12 The Alkanes Kerboodle Answers: Page No. 192

1. Ans-

Methylbutane.

2. Ans-

3.Ans-Heptane 4.Ans- Heptane will have a higher melting temperature because its Straight chains will pack together more closely.

12.2 Fractional distitlation of crude oil AQA AS Chemistry C12 The Alkanes Kerboodle Answers : Page No. 195

1. Ans- 2.Ans- Petrol 3.Ans- Fractional distillation separates a mixture into several components with different ranges of boiling temperatures whereas distillation simply separates all the volatile components of a mixture from the non-volatile ones. 4.Ans- e.g .. methane, ethane, propane. butane 12.3 Industrial cracking: Page No. 19 1.Ans-Decane →octane + ethene 2.Ans- Many or the productsare gases rather than liquids. 3.Ans- Octane itself has a short enough chain length to be in demand. 4.Ans-By using a catalyst 5.Ans-Shon chain products are in greater demand than long chain ones. Alkene~ arc more useful than alkanes as starting material~ for further chemical reactions.

12.4 Combustion of alkanes AQA AS Chemistry C12 The Alkanes Kerboodle Answers: Page No. 200

1.Ans- a b

2. a They produce carbon dioxide (a greenhouse gas) when they bum. They may produce poisonous carbon monoxide when burnt in a restricted supply of oxygen. They are in general non-renewable resources. They may produce nitrogen oxides and sulfur oxides when burnt. Cancercausing carbon particulates may be produced and unburnt hydrocarbons (which contribute to pho10chemical smog) may he released into the atmosphere.

b.Burn as little fuel as possible and/or offset the CO₂ produced by planting trees, for example. Ensure that burners arc serviced and adjusted to burn the fuel completely. Remove sulfur from the fuel before burning or remove SO₂ from the combustion products (by reacting with calcium oxide, for example). 3. Possibilities include wind power, wave power and nuclear power.

12.5 The formation of halogen alkanes AQA AS Chemistry C12 The Alkanes Kerboodle Answers: Page No. 203

1.Ans- a termination b propagation c propagation d initiation 2 a b

Practice questions: Page No. 204-205

1. (a) (Same) General formula /allow a named homologous series with its general formula  Chemically similar/same (chemical) reactions  Same functional group  Trend in physical properties/ e.g., including boiling point as Mr increases  (Molecules) increase by CH2/Mr = 14

1. b) Fractional distillation/ fractionation/ chromatography

(c) (Molecules/compounds/substances) with the same molecular formula / same number and type of atoms but different structural formula/ different displayed formula/ different arrangement of atoms/different structures 2,4-dimethylhexane C₄H₉

1. d) Less surface contact / less surface area/ less polarisable molecule so fewer/weaker/less Van der Waals‟/vdw forces

2 (a)

1. b) Solidifies /freezes /goes viscous /waxing occurs

(c) (i) Spark/ (very) high temp/ 2500 °C – 4000 °C (ii) 2CO + 2NO → 2CO₂ + N₂ (iii)) (d) Ans- (i) High temp/ anywhere in range 400 °C – 900 °C/ anywhere in range 670-1200 K / high pressure/ anywhere in range 5000 kPa up to 8000 kPa/ (ii) (iii) Polymers/ plastics/ named polymer 3.Ans- a) (i) Crude oil / oil / petroleum (ii) Fractional distillation / fractionation / fractionating

1. b) (i) 5

(ii) Chain (isomerism)

1. c) (i)C₁₂H₂₆/ H₂₆C₁₂

(ii) Thermal cracking High temperature (400 °C ≤ T ≤ 900 °C) or (650 K ≤ T ≤ 1200 K) and High pressure (≥ 10 atm, ≥ 1 MPa, ≥1000 kPa) (iii) To produce substances which are (more) in demand / produce products with a high value / products worth more d). (i) Corrosive or diagram to show this hazard symbol (ii) 120.5 / ( 86 + 71 ) × 100 =76.75% or 76.8% (e). 2,2-dichloro-3-methylpentane C₃H₆Cl 4 . a) (i) (ii) Not enough oxygen or air (available for complete combustion) /lack of oxygen or air / too much octane

1. b) (i)

(ii)) Pt / Pd / Rh / Ir or names Big(ger) surface area / increased reaction rate / removes more of the gases / ensures complete reaction

1. c) (i) Acid rain

(ii) CaO/ lime / CaCO3 /limestone Neutralises the gas or words to that effect/it is basic/ SO2 is acidic 5 (a)

1. b) (i) (Chlorine free) radical

(ii) Banner 2

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