Chapter 10 Organic Reactions (Triple Only) Flashcards
What are alkenes?
Alkenes are a homologous series of hydrocarbons with a C=C double bond as their functional group.
What is the general formula for alkenes?
The general formula for alkenes is CnH2n.
Where do we get alkenes from?
Alkenes are the main product of cracking.
Name and give the molecular and displayed structural formula for the first 4 alkenes.
The first 4 alkenes are:
Give the word and chemical equation for the complete combustion of ethene.
Alkenes can completely combust in oxygen to produce water and carbon dioxide. This is similar to the complete combustion of alkanes.
Example:
ethene + oxygen → carbon dioxide + water
C2H4 + O2 → CO2 + H20
Why do we not burn alkenes for fuel?
When alkenes burn they release less energy than alkanes because they are less able to combust completely so incomplete combustion occurs. For this reason burning alkenes results in yellow smokey flames and they are not used as fuels.
What does unsaturation mean?
Unsaturated refers to hydrocarbons that contain at least one double bond. Alkenes are therefore unsaturated.
Why are alkenes more reactive than alkanes?
Alkenes are more reactive than alkanes due to the C=C double bond.
Write a word equation and chemical equation to show the reaction between ethene and bromine. What is this type of reaction called?
When alkenes react with halogens the double bond is broken and the halogens are added to the molecule. This is an example of an addition reaction.
Example:
What name do we give to the addition reaction between an alkene and a halogen?
When a halogen is added to an alkene it is called halogenation.
Write the word and chemical equation and conditions required for the reaction between ethene and hydrogen.
Alkenes react with hydrogen in an addition reaction to form an alkane. This reaction requires a nickel catalyst and must take place at 60°C.
Example:
What name do we give to the addition reaction between an alkene and hydrogen?
When hydrogen reacts with an alkene it is called hydrogenation.
What is formed when an alkene reacts with steam (water)?
Alkenes react with steam (water) to form an alcohol.
Write the word equation for the reaction between ethene and steam (water). Include the conditions.
The reaction between an alkene (like ethene) and steam (water) is reversible so must be carried out at high pressure and a high temperature. A catalyst is also required.
What name do we give to the reaction between an alkene and steam (water).
The reaction between an alkene and steam (water) is called hydration.
What are alcohols?
Alcohols are a homologous series with the functional group -OH called hydroxyl.
Give the name, molecular formula and displayed structural formula for the first 4 alcohols.
The first 4 alcohols are:
What is methanol used for?
Methanol is used as a chemical feedstock.
What are feedstocks?
Feedstocks are chemicals used to make other products.
What are the main 2 uses for alcohols? What is ethanol used for?
Alcohols are used as solvents and fuels. Ethanol is used in alcoholic drinks.
Write the word then chemical then balanced chemical equations for the complete combustion of ethanol.
Alcohols completely combust in oxygen to produce water and carbon dioxide. This is similar to the complete combustion of alkanes.
Write the word and chemical equation for the reaction of ethanol with sodium.
Alcohols react with sodium metal to form a solution of sodium alkoxide. Hydrogen gas is released.
What organisms are involved in fermentation and what is the essential condition?
Alcohols can be produced through fermentation by yeast. Fermentation happens in anaerobic conditions.
What does anaerobic mean?
Anaerobic means in the absence of oxygen.
Give the equation for fermentation and include the essential conditions.
The equation for fermentation is:
How can ethanoic acid be formed from ethanol?
Ethanol can be oxidised by microbes or chemical agents to produce ethanoic acid.
What is vinegar?
Ethanoic acid is another name for vinegar so vinegar can be made from the oxidation of ethanol.
Give an example of a carboxylic acid.
Ethanoic acid is an example of a carboxylic acid.
What are carboxylic acids?
Carboxylic acids are a homologous series with a functional group of -COOH
Give the names, molecular formula and displayed structural formula for the first 4 carboxylic acids.
The first 4 carboxylic acids are:
What happens when carboxylic acids dissolve in water?
Carboxylic acids dissolve in water to make acidic solutions.
Why do carboxylic acids make weak acids?
Carboxylic acids make weak acids in solution because they do not completely ionise in solution. They have a lower pH than strong acids of the same concentration.
Write the word, chemical and balanced chemical equations for the reaction between ethanoic acid and sodium carbonate.
Carboxylic acids react with carbonates to produce carbon dioxide, a salt and water.
What is the test for carbon dioxide?
The test for carbon dioxide is that it turns lime water from clear to cloudy.
How are esters formed?
Carboxylic acids react with alcohols to produce esters.
Give the word equation for the reaction between a carboxylic acid and an alcohol.
The reaction between a carboxylic acid and an alcohol is:
carboxylic acid + alcohol → ester + water
Give the word equation and condition required for the reaction between ethanoic acid and ethanol.
Ethanoic acid reacts with ethanol to produce the ester ethyl ethanoate. This requires an acid catalyst.
Give 2 features and 2 uses for esters.
Esters are volatile (evaporate easily) and have smells. They are often used in flavourings and perfumes.
