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chem 1.5.
organic chem
| Question | Answer |
|---|---|
| what are alkANES? | SATURATED hydrocarbons, general formula = Cn H2n+2 |
| How many bonds can carbon atoms form? | 4 (maximum) |
| what are cycloalkanes? | ring of carbon atoms general formula= CnH2n |
| What are structural isomers? | different arrangements of the same atom |
| What structural isomers can alkanes form? | Chain isomers, only when c-c bonds are switched (onto another carbon atom in the chain) is it an isomer. It is the SAME arrangement if it is rotated! |
| What do alkanes burn in? | Oxygen |
| What happens when alkanes form halogenoalkanes? | FREE RADICAL SUBSTITUTION. |
| What is free radical substitution? | Halogens reacting with alkanes, it can only be started by UV LIGHT. |
| What are the steps of free radical substitution? | 1)initiation reaction- free radicals produced 2) propagation reactions- free radicals used up- in chain reactions 3)Termination reactions-free radicals form stable molecules |
| What is crude oil? | A mixture of hydrocarbons |
| What is petroleum? | crude oil, made mostly of alkanes. |
| How do you separate crude oil? | Fractional distillation |
| What are the steps of fractional distillation? | 1) vaporised at 350c 2)fractionating column- largest dont vaporise turn into residual. 3)vapor goes up- is cooled, and condenses, therefore drawn off. 4) lowest boiling points don't condense- turn into gases |
| What happens to the products in fractional distillation? | light fractions are more valuable-higher demand so are stored/sold. Heavy fractions are cracked. |
| What is cracking? | Breaking long chained alkanes into smaller hydrocarbons. |
| What are the conditions for thermal cracking? | high temp, high pressure. AlkENES are cracked using this method, form POLYMERS. |
| What are the conditions for catalytic cracking? | form motor fuels. aromatic, ZEOLITE catalyst, slight pressure, high temp |
| What can alkanes be reformed into? | cycloalkanes and aromatic hydrocarbons |
| what are uses of alkane fuels? | methane- used in cooking, central heating -petrol -jet fuel -diesel |
| what is the disadvantage of using alkanes? | are expensive, non-renewable, run out, PRODUCE EMISSIONS. |
| What emissions are produced from alkanes? | sulfur dioxides- scrubbers used to reduce output. Are poisonous. Produce acid rain- sulfuric acid. Carbon monoxide- formed by incomplete combustion, is a poisonous gas. Nitrogen oxide- forms acid rain, causes breathing problems- affects ozone layer. |
| What are greenhouse gases? | Formed from alkanes, absorb infrared leading to global warming. |
| AlkENES are? | UNSATURATED hydrocarbons. Formula= CnH2n |
| Alkene properties? | Are more reactive, have a double bond consisting of a pi and sigma bond. The double bond has a high electron density. |
| Adding hydrogen to c=c bonds produces? | AlkANES via ELECTROPHILIC ADDITION |
| What are the conditions for electrophilic addition? | nickel catalyst at 150c. |
| What happens in electrophilic addition? | Double bond opens- the pi bond is an electron rich area (is nucleophilic), which attracts the electrophile (hydrogen) meaning the hydrogen attaches itself to each of the carbons. |
| What is an electrophile? | Are electron pair acceptors, they are short of electrons, therefore are attracted to electron rich areas. Examples- Positively charged ions- H+ -Polar molecules |
| What is an nucleophile (electron rich area)? | A area high in electrons which is attracted to places which don't have enough electrons. The double bond in C=C is nucleophilic. |
| What is a hazard? | anything that can cause harm |
| What is a risk? | chance of what you are doing can cause harm |
| what is a risk assessment? | is created to reduce risks, -working in a smaller scale -appropriate precautions, e.g. wearing eye protection -safer chemicals- lower concentration THIS MINIMISES RISK. |
| Hydrogen halides form (with a unsymmetrical alkene)? | 2 products, mostly form the most stable carbocation! |
| Alkenes do what when they react with halogens and hydrogen halides? | ELECTROPHILIC ADDITION. |
| In order of stability, what are the most stable carbocations? | tertiary, secondary, primary. |
| What is the two tests for an alkene? | bromine water- turns colourless with alkenes, because the c=c bonds undergo electrophilic addition with bromine water. Alkenes are oxidised in acidified potassium manganate. turns from purple- to colourless. |
| E/z Isomerism? | Double bonds cant rotate, therefore carbons all lie on the same plane (are trigonal planar). Therefore their structural isomers are the same atoms but different arrangement- steroisomerism. |
| E isomerism | Is an isomer with DIAGONAL rotation. When the same groups are diagonally across the double bond. |
| What is stereoisomerism? | Are atoms with the same structural formula but different arrangement. Because of the lack of rotation, some alkenes have stereoisomers. |
| Z isomerism? | Is an isomer with VERTICAL AND HORIZONTAL rotation. When the same groups are vertically or horizontally across the double bond. |
| Cis isomerism? | Z isomer. This only applies if they have the same groups attached to them. |
| Trans isomerism? | REMEMBER 'trane' is a E isomer. This only applies if they have the same groups attached to them. |
| Alkenes can join to form? | additional polymers |
| What happens to the double bond in additional polymers? | The double bonds open up to form a long chain- a monomer (a repeated unit) forms lots of polymers! |
| What do polymers form? | Plastics (mostly) |
| What happens to waste polymer plastics? | waste plastics, can either be buried, recycled, or burned. |
| What is the problems with burying plastics? | they are unreactive, and non-biodegradable, meaning they lead to environmental damage. |
| What happens in the process of recycling? | plastics are sorted, them melted molded/remodeled down to make new plastics. |
| What is the problems of burning plastics? | heat is used, wasting electricity, toxic gases can be released (are prevented using a scrubber to neutralize) |
| Properties of biodegradable polymers? | decompose under right conditions. Are made from starch. Renewable materials- oil fractions. |
| What are the problems with biodegradable polymers? | you have to collect and separate them from other plastics. Are more expensive. |
Created by:
brontemunro
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