Flashcards · 5070 · Topic 11

Organic chemistry flashcards

43 cards on Topic 11, subtopics 11.1 to 11.8. Pick a subtopic or study them all.

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Functional group: An atom or group of atoms that determines the chemical properties of a homologous series.
Homologous series: A family of compounds with the same functional group and similar chemical properties.
Saturated: Contains only single carbon–carbon bonds (e.g. alkanes).
Unsaturated: Contains at least one carbon–carbon double or triple bond, most commonly C=C (e.g. alkenes).
Homologous series: the full description: Same functional group, same general formula, each member differs by CH₂, a gradual trend in physical properties, similar chemical properties.
Structural isomers: Compounds with the same molecular formula but different structural formulae.

Name endings for alkanes, alkenes, alcohols and carboxylic acids: Alkane: -ane. Alkene: -ene. Alcohol: -ol. Carboxylic acid: -oic acid.
Name C₂H₅OH and CH₃COOH: Ethanol and ethanoic acid.
Name the two unbranched alkenes with formula C₄H₈: But-1-ene and but-2-ene.
Name the ester formed from propanoic acid and methanol: Methyl propanoate — the alcohol part is named first.

Three fossil fuels, and the main constituent of natural gas: Coal, natural gas and petroleum. Natural gas is mainly methane.
How is petroleum separated?: By fractional distillation, into fractions with different boiling point ranges.
Going UP the fractionating column: chain length, boiling point, volatility, viscosity: Chain length decreases, boiling point is lower, volatility is higher, viscosity is lower.
Uses of: refinery gas, gasoline, naphtha, kerosene: Refinery gas: heating and cooking. Gasoline/petrol: car fuel. Naphtha: chemical feedstock. Kerosene/paraffin: jet fuel.
Uses of: diesel oil, fuel oil, lubricating oil, bitumen: Diesel oil/gas oil: diesel engines. Fuel oil: ships and home heating. Lubricating oil: lubricants, waxes, polishes. Bitumen: making roads.

General formula of the alkanes: CₙH₂ₙ₊₂
Reactivity of alkanes: Generally unreactive, apart from combustion. They are saturated hydrocarbons.
Products of the complete combustion of an alkane: Carbon dioxide and water.
Reaction of methane with chlorine: type, condition and equation: Substitution, in ultraviolet light. CH₄ + Cl₂ → CH₃Cl + HCl

General formula of the alkenes: CₙH₂ₙ
Cracking: Breaking larger alkane molecules into smaller alkanes, alkenes and hydrogen, using a high temperature and a catalyst.
Why is cracking done?: There is more demand for short-chain fractions such as petrol than is supplied, and the alkenes made are useful (for example, to make polymers).
Test to tell an alkene from an alkane: Add bromine water. Alkene: orange → colourless. Alkane: stays orange.
Addition reactions of ethene: catalyst and product with hydrogen and with steam: Hydrogen: nickel catalyst → ethane. Steam: acid catalyst → ethanol.

Two ways of making ethanol: Fermentation of glucose with yeast. Catalytic addition of steam to ethene.
Conditions for fermentation: 25–35 °C, yeast, absence of oxygen.
Conditions for making ethanol from ethene and steam: 300 °C, 6000 kPa (60 atm), acid catalyst.
Two uses of ethanol: As a solvent and as a fuel.
Fermentation compared with hydration of ethene: Fermentation: renewable raw material, but slow, batch process, dilute impure product. From ethene: fast, continuous, pure product, but uses a non-renewable raw material and lots of energy.
Complete combustion of an alcohol: products and two examples: Carbon dioxide and water. C₂H₅OH + 3O₂ → 2CO₂ + 3H₂O 2C₃H₇OH + 9O₂ → 6CO₂ + 8H₂O (propan-1-ol)

Ethanoic acid + a metal: Salt + hydrogen. 2CH₃COOH + Mg → (CH₃COO)₂Mg + H₂ (magnesium ethanoate)
Ethanoic acid + a base: Salt + water. CH₃COOH + NaOH → CH₃COONa + H₂O (sodium ethanoate)
Ethanoic acid + a carbonate: Salt + water + carbon dioxide. 2CH₃COOH + Na₂CO₃ → 2CH₃COONa + H₂O + CO₂
Two ways of making ethanoic acid: Oxidising ethanol with acidified potassium manganate(VII), or by bacterial oxidation (fermentation of ethanol in air).
Making an ester: Carboxylic acid + alcohol, with an acid catalyst → ester + water. Ethanoic acid + ethanol → ethyl ethanoate.
Why does ethanoic acid react more slowly than hydrochloric acid of the same concentration?: Ethanoic acid is a weak acid: it is only partially dissociated in water, so there are fewer H⁺ ions.
Do other carboxylic acids react like ethanoic acid? Give an example.: Yes — methanoic and propanoic acids give methanoates and propanoates. 2C₂H₅COOH + Mg → (C₂H₅COO)₂Mg + H₂ (magnesium propanoate)

Polymer: A large molecule built up from many small units called monomers.
Problems with disposing of plastics: Most are non-biodegradable, so they fill landfill and harm aquatic life; burning them can release toxic gases.
Addition polymerisation: Many monomers with a C=C double bond join together. Nothing else is formed. Ethene → poly(ethene).
Polyamide (nylon): A dicarboxylic acid + a diamine → amide link –CONH–, with water lost.
Polyester (PET): A dicarboxylic acid + a diol → ester link –COO–, with water lost.
Proteins as polymers: Natural polyamides formed from amino acid monomers.