Ethanol
Ethanol is the An organic compound containing a hydroxyl group, -OH. The 'alcohol' in alcoholic drinks is ethanol, produced by the fermentation of sugars and found in wines, spirits and beers. found in beer, wine and other alcoholic drinks. It is also used as a Material that is used to produce heat, like coal, oil or gas. for vehicles, either on its own or mixed with petrol. Ethanol can be produced by Type of anaerobic respiration carried out by yeast. and concentrated using In fractional distillation a mixture of several substances, such as crude oil, is distilled and the evaporated components are collected as they condense at different temperatures..
Fermentation
Fermentation is an Without oxygen. process (it happens in the absence of oxygen):
Glucose 鈫 ethanol + carbon dioxide
A unicellular fungus used in the brewing and baking industries., a type of single-celled A large group of eukaryotic organisms that contain single celled yeasts, moulds and mushrooms., provides the A protein which catalyses or speeds up a chemical reaction. needed for fermentation. If the yeast Basic unit of life. Unicellular organisms only have one cell. Multicellular organisms have many cells. become too cold, fermentation happens very slowly, or may not happen at all. If the yeast cells become too hot, their enzymes become To change the shape of an enzyme's active site, for example because of high temperatures or extremes of pH. Denatured enzymes no longer work. and fermentation stops.
The typical conditions needed for fermentation include:
- sugars A substance is said to be dissolved when it breaks up and mixes completely with a solvent to produce a solution. in water, and mixed with yeast
- an air lock to allow carbon dioxide out, while stopping air getting in
- warm How warm or cold something is., 25-35掳C
The yeast dies when the ethanol The concentration of a solution tells us how much of a substance is dissolved in water. The higher the concentration, the more particles of the substance are present. reaches about 15%. Fermentation is a slow reaction and takes several days or weeks to finish. If air is present, the oxygen causes the ethanol to oxidise to ethanoic acid, so the drink tastes of vinegar.
Question
Describe and explain what happens to the limewater during the experiment shown above.
The limewater turns milky. This is because carbon dioxide is produced during fermentation, and passes through the limewater.
Fractional distillation
The fermentation mixture contains yeast cells and Unable to dissolve in a particular solvent. For example, sand is insoluble in water. substances. These are separated from the impure ethanol solution by Method used to separate an insoluble solid from a liquid using a physical barrier such as paper.. Fractional distillation is then used to produce a concentrated solution of ethanol from the Fluid that has passed through a filter.. This works because ethanol and water have different The temperature at which a substance rapidly changes from a liquid to a gas.. When the mixture is heated, ethanol The process in which a liquid changes state and turns into a gas. more readily.
Image caption, Distillation process to separate ethanol from water
1. Water and ethanol solution is heated
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It is safer to use an electric heater instead of a Bunsen burner. This is because ethanol liquid and vapour are highly Able to ignite and burn., and could be set on fire by accident.