11765085
Description
Flashcards by finn squires, updated more than 1 year ago
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Created by finn squires
over 6 years ago
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| Question | Answer |
| What is a hydrocarbon? | Any compound that is formed from carbon and hydrogen atoms only. |
| What are alkanes? | Alkanes are the simplest hydrocarbon. Formula is CnH2n+2. Contains single C-C bonds only. They are saturated compounds (each C has 4 single covalent H bonds). First four are methane (1C), ethane (2C), propane (3C), butane (4C). |
| What happens to the properties of hydrocarbons as the chain gets shorter? | As the chain gets shorter: -the less viscous (gloopy) the hydrocarbon is. -the more volatile the hydrocarbons (easily evaporate) therefore lower BP. -the more flammable the hydrocarbon is. |
| What is complete combustion? | Plent of oxygen and releases lots of energy. Hydrocarbon + oxygen ---> Carbon dioxide + water (+energy). The hydrocarbon is oxidised. |
| What is crude oil? | A mixture of hydrocarbons. |
| What is a fossil fuel? | Made up of dead sea creatures which died millions of years ago but didn't rot. As layers of sediment built up, high pressure and temperature converted them to oil. |
| Explain how fractional distillation separates a hydrocarbon into factions? | Crude oil heats up and evaporates. Vapours travel up the fractionating column which has a temp gradient (hot at bottom cool at top). The larger hydrocarbons have a higher BP so condense and drain out early on. The shorter hydrocarbons have a lower BP so condense and drain out later on at the top where its cooler. Separated into factions of similar BPs. |
| What are organic compounds? | Compounds containing carbon atoms. |
| What is a homologous series? | A homologous series is a group of similar compounds with similar properties. |
| What is catalytic/steam cracking? | Catalytic/steam cracking breaks a large alkane into a smaller alkane and an alkene. It produces a smaller more volatile alkane (better fuel) and a useful feedstock for making plastics. |
| What are the two methods of cracking? | Cracking is a thermal decomposition reaction(break down by heating). Catalytic cracking - vaporise the hydrocarbon then pass it over a hot powdered aluminium oxide catalyst. The long chain molecules split apart on the surface of the catalyst. Steam cracking - mix hydrocarbon vapours with seam and heat them to a high temperature. |
| What are alkenes? | Hydrocarbons that have a C=C double bond. Unsaturated (only have 2 H bonds for each C), C=C double bond can open up to make single bonds making alkenes far more reactive than alkanes. The formula for alkenes is CnH2n+2. The first five are; ethene (2C), propene (3C), butene (4C), pentane (5C). |
| What is the incomplete combustion of alkenes? | In large amounts of oxygen, alkenes combust completely but in air they only incompletely combust producing C, CO, CO2. Alkene + oxygen ---> carbon + carbon monoxide + carbon dioxide + water. It gives a smokey yellow flame. |
| What is an addition reaction? |
Alkenes react via addition reactions.
Image:
Add (binary/octet-stream)
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| What is the hydrogenation of an alkene and what catalyst does in need? | Alkene reacts with H2 (hydrogenation) in the presence of a nickel catalyst to produce an alkane. |
| What is the halogenation of an alkene and what catalyst does in need? | Alkene reacts with Br2 (halogenation). When an alkene is added to bromine water and shaken it turns it colourless as the compound is colourless. |
| How do you turn an alkene into an alcohol and what catalyst does in need? | Alkene reacts with H2O (steam) in the presence of a phosphoric acid catalyst to produce an alcohol. |
| What are polymers? | Polymers are long chain molecules that make up plastics. Usually their monomers are alkenes. When the small chain monomers join together it usually needs high pressure and a catalyst - polymerisation. |
| Explain how addition polymers are made? | Lots of unsaturated monomer molecules (alkenes) with a double covalent bond can open up these double bonds and join together to form polymer chains. This is addition polymerisation. |
| What are alcohols? | They have an -OH group. Name ends in ___ol. The formula is CnH2n+1OH. The first four are methanol, ethanol, propanol and butanol. |
| What are the properties of alcohols? | Flammable, soluble in water (1C, 2C, 3C, 4C similar properties) solutions have pH 7, react with sodium to produce hydrogen, can be oxidised to produce a carboxylic acid, used as solvents and fuels (soluble/flammable). |
| What are the two main ways of making alcohol? | Fermentation: Sugar ---> alcohol + carbon dioxide. Low yield, needs distilling, low temp 37oC (yeast), renewable. Hydration of an alkene: C2H4 + H2O ---> C2H5OH. Higher temp (100oC), non-renewable (crude oil), 100% yield. |
| What is a carboxylic acid? | Have a -COOH group, ends in ___anoic acid (meth, eth, prop, but). |
| What are the properties of a carboxylic acid? | React with a carbonate (fizzes) to produce salt, water and CO2. Salt ends in ___anoate. |
| Explain what happens when carboxylic acids dissolve in water? | They ionise and release H+ ions resulting in an acidic solution. But because they don't fully ionise (not all molecules release ions) they form weak acid solution. So have higher pH (less acidic) than solutions of strong acids with the same concentration. |
| What is an ester? | Made from an alcohol and a carboxylic acid . They have a -COOC- group. Acidic catalyst is usually used in the reaction. |
| Explain condensation polymerisation? | Involves monomers with contain different functional groups. The monomers react together and bonds form between them, making polymer chains. For each new bond a small molecule (e.g. water) is lost, hence the name condensation. |
| How is a polypeptide formed? | Condensation polymerisation between carboxylic acid group (-COOH-) and an amine group (-NH2) to produce a polypeptide and water. |
| How is a polyester formed? | Condensation polymerisation between carboxylic acid group (-COOH-) and an alcohol group (-OH) to produce a polyester and water. |
| What are the differences between addition polymerisation and condensation polymerisation? | Addition: only one monomer type C=C (alkene), only one product, C=C double bond in monomer. Condensation: two monomer types each containing two of the same functional groups or one monomer with two groups, two types of product (polymer and small molecule e.g. water), two reactive groups on each monomer. |
| What is the formula for amino acids? | Amino acids have two functional groups (amino -NH2 and an acidic carboxyl group - COOH e.g. glycine. |
| How can amino acids form proteins? | Amino acids can form polypeptides via condensation polymerisation. Order of amino acids changes the protein. |
| What are DNA made out of? | DNA (deoxyribonucliec acid) is a large molecule that takes a double helix structure. Two polymer chains of monomers called nucleotides. Different polymer chains link up with different bases the order of bases acts as a code. Bases form cross links for the structure (double helix). |
| How can sugars form polymers? | Simple sugars (saccharides) can form polymers called polysaccharides such as starch. |
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