Fermenting Sugars Fermentation Reaction Plants that contain starch (and therefore sugars) are the starting material for making alcohol. The reaction is called fermentation where a sugar solution is converted into an alcoholic solution.

When a sugar is being fermented a gas is produced. The reaction is catalysed by yeast. Therefore the yeast remains unchanged. Catalyst: a substance that accelerates a chemical reaction without itself being affected

The gas produced during fermentation is carbon dioxide. Carbon dioxide can be tested by adding lime water, if it turns cloudy then carbon dioxide is present.

The equation for the fermentation reaction is: glucose → ethanol + carbon dioxide C 6 H 12 O 6 → 2C 2 H 5 OH + 2CO 2

Biological Action Yeast: Living organism Microscopic fungus Feeds on sugars Is a biological catalyst Therefore classed as an enzyme

Conditions for fermentation: pH: prefer a neutral pH (or round about) if it is too acidic or alkaline the yeast will die. Temperature: Room temperature is ideal; too cold and the yeast stops working (goes into a “sleep” state) and too warm and it dies. Alcohol concentration: yeast does not like alcohol, about 14% alcohol the yeast dies

Distillation The alcohol concentration, as mentioned before, kills the yeast if it reaches about 14%, to increase the percentage of alcohol the alcohol has to be separated from the rest of the mixture (the water), this is done via a process called distillation.

Distillation is a method of separating liquids of different boiling point by evaporation followed by condensation. The separation by distillation is an easy process due to the fact that alcohol boils at 79 O C and water boils at 100 O C although both liquids will evaporate to some extent at any temperature.

Alcoholic Drinks The chemical name for the alcohol that is found in all drinks is called ethanol (C 2 H 5 OH); it also has an effect on human bodies when they consume it. Ethanol belongs to the alcohol family of compounds. Another member of the family, methanol can cause blindness followed by death!

The alcohol contained in all these drinks is ethanol; this substance relaxes the mind therefore affecting the speed at which the brain processes information, so everyday tasks such as driving can be dangerous. If alcohol is consumed in extreme amounts it causes dizziness, aggressiveness, unconsciousness and even death. The long term effects of alcohol abuse can be a liver disease known as cirrhosis and heart problems.

Alcoholic DrinkCarbohydrate Source WineGrapes CiderApples BeerWheat and barley WhiskyWheat and barley VodkaPotatoes, wheat and barley GinPotatoes, wheat and barley CalvadosApples SakiRice BrandyGrapes