Ethanol can be made by the hydration of ethene or by the fermentation of sugars
How is ethanol made by hydration?
Ethanol is manufactured industrially by the CATALYTIC hydration of ethene, using steam in the prescence of a PHOSPHORIC ACID catalyst. The reaction is carried out at HIGH TEMPERATURE and MODERATE PRESSURE and can be operated CONTINUOUSLY
Is the hydration of ethene reaction reversible and what does this mean? What happens to any unreacted gases?
The reaction is REVERSIBLE and so the conversion of ethene is INCOMPLETE - only 5% of the ethene is converted into ethanol. Any unreacted gases are RECYCLED and are passed through the reactor again. Overall, 95% conversion achieved.
How is ethanol produced by fermentation?
Carbohydrates are converted into ethanol and carbon dioxide - sugar or starch is usually used as the carbohydrate source. Fermentation is carried out in solution at relatively low temperatures, in the prescence of yeast. The reaction is CATALYSED by an ENZYME in the yeast.
Is the fermentation of carbohydrates to ethanol anaerobic or aerobic?
The fermentation of carbohydrates to ethanol is ANAEROBIC - it does not require oxygen, therefore it is important that fermentation is carried out in the ABSENCE OF AIR.
Is fermentation slow or fast at 25 degrees? What about 37 degrees?
Reaction is slow at temperatures below 25 degrees, while at temperatures above 37 degrees, the enzyme starts to denature and lose its efficiency
What melting and boiling points do alcohols have and what is this down to?
Hydrogen bonds are the strongest intermolecular forces. The relatively high melting and boiling points of alcohols result from the prescence of hydrogen bonds between the alcohol molecules.
What do the high melting and boiling points and the hydrogen bonds mean about volatility for alcohols and what is volatility?
Volatility is the ease that a liquid turns into a gas, and it increases as boiling point increases. Alcohols have a relatively low volatility
Do alcohols dissolve in water? Why do they/don't they?
Alcohols DISSOLVE IN WATER because hydrogen bonds form between the polar -OH groups of the alcohol and water molecules.
Does solubility increase or decrease as chain length increases?
Solubility decreases as the chain length increases, because a larger part of the alcohol is made up of a non-polar hydrocarbon chain, and the hydrocarbon chain does not form hydrogen bonds with water molecules.
What general formuala do the halogenoalkanes have?
Halogenoalkanes have the general formula CnH2n+1X, where X represents the halogen atom
Do halogenoalkanes contain single or double bonds?
Halogenoalkanes contain only single bonds.
What do halogenoalkanes contain?
Halogenoalkanes contain a polar carbon-halogen bond. The halogen atoms are more electronegative than the carbon atoms. The bonded electron pair is attracted more towards the halogen atom than towards the carbon atom. The result is a polar bond
Does the polarity of the halogens increase or decrease going down the group?
The electronegativity of the halogens decreases down the group, resulting in a decrease in polarity of the carbon-halogen bond from fluorine to iodine
What do halogenoalkanes react with and what is this called?
Halogenoalkanes react with nucleophiles in substitution reactions.
What happens during these reactions with the halogenoalkanes?
The electron-deficient carbon atom in halogenakanes attracts nucleophiles such as water, OH- and NH3. The nucleophile replaces the halogen atom in the halogenoalkane, forming a compound containing a different functional group.