Energy and fuels

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1 calorie is 4.2 joules.(little c) 1 calorie is the amount of energy needed to raise the
temperature of 1g of water by 1 degree.
1 Calorie is 4200 joules.(BIG C) 1 Calorie is the amount of energy needed to raise the
temperature of 1kg of water to 1 degree.
In food labels they sometimes write kilocalories or kcal but sometimes they write Calories so
look out for this.
Different foods produce different amounts of energy. Foods with high proportions of
carbohydrates, fats and oils produce relatively large amounts of energy. Proteins are not used
in our bodies for energy so on packets of food proteins will be lower in kcal as they are not
used as energy whereas carbohydrates will be higher in kcal.
Your body needs energy to conduct every day activities e.g. breathing, heart beating etc. We
need energy for the chemical reaction which are constantly going on in our cells. The energy
we get from our food is chemical energy. This energy is released by respiration.
Glucose + Oxygen > Carbon dioxide + Water + Energy
If the food we eat contains more energy than your body needs or uses, the excess energy is
stored by your body as fat. Continually taking in more energy than than your body needs/uses
up will result in obesity. Which can lead to diabetes, heat disease etc.
When you eat less food than your body needs, your body uses up some of its own fat stores.
Calorie controlled diets are designed to give your body slightly less energy than it needs so a
person who needs e.g. 2500 kcal a day would eat 2100 kcal a day and will gradually lose
more and more fat as the your body will use up it's own fat stores. Most calorie controlled
diets are lowfat diets which avoid sugars as they are high in energy and stimulate the
appetite. They do however recommend slow release carbohydrates e.g. whole meal bread to
keep you fuller for longer so you are less likely to snack.

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The method of measuring the amount of energy released by burning a substance is called
calorimetry.
Method:
Put 50grams of water in a copper can (As it is a good conductor of heat.)
Your fuel e.g. propane, butane goes into the spirit burner and is weighed as well as the lid.
Record starting temperature
Place spirit burner under the can and light the wick. Heat the water up to 50 degrees.…read more

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We can do this similar method with a polystyrene cup. The types of question you could get are
things like what is wrong with this test?
Te biggest problem is amount of energy loss to the surroundings. We can reduce this by
insulating the cup with cotton wool and the use of a lid reduces energy loss by evaporation.
There is a high demand for fuels e.g. electricity, heating, cars, planes etc.…read more

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