• Determination of the energy content of food by combustion
Determining Energy Content
The energy content of food can be estimated by burning a sample of known mass and measuring the energy released via calorimetry
- Combustion of the food source causes the stored energy to be released as heat, which raises the temperature of water
- The amount of energy required to raise 1 g of water by 1ºC is 4.18 J – this is the specific heat capacity of water
The equation for calculating the energy content of a food source via calorimetry is as follows:
- Energy (joules) = Mass of water (g)× 4.2 (J/gºC)× Temperature increase (ºC)
The biggest source of error in calorimetry is usually caused by the unwanted loss of heat to the surrounding environment
- The food sources should be burnt at a constant distance from the water to ensure reliability of results
- The initial temperature and volume of water should also be kept constant (1 g of water = 1 cm3 or 1 ml)
Measuring Energy Content of Food via Calorimetry
Comparing Energy Content
The three types of nutrients that are commonly used as energy sources arecarbohydrates, lipids (fats) and proteins
- Carbohydrates are preferentially used as an energy source because they are easier to digest and transport
- Lipids can store more energy per gram but are harder to digest and transport (hence are used for long-term storage)
- Protein metabolism produces nitrogenous waste products which must be removed from cells
The relative energy content of carbohydrates, proteins and fats are as follows:
- Carbohydrates – 1,760 kJ per 100 grams
- Proteins – 1,720 kJ per 100 grams
- Fats – 4,000 kJ per 100 grams
Role of Organic Molecules in Energy Production
The sun is the main source of energy on Earth. Other energy sources include coal, geothermal energy, wind energy, biomass, petrol, nuclear energy, and many more. Energy is classified into various types based on sustainability as renewable sources of energy and non-renewable sources of energy.What are the 5 sources of energy? ›
- Solar energy from the sun.
- Geothermal energy from heat inside the earth.
- Wind energy.
- Biomass from plants.
- Hydropower from flowing water.
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We use energy to not only heat our human-made structures but we use it to cool them as well. Energy is necessary for getting up out of bed, walking down the street, or even lifting your finger. It's also necessary in abundance for all types of modern conveniences, from light bulbs to appliances to vehicles.What are the 3 main sources of energy? ›
The three major categories of energy for electricity generation are fossil fuels (coal, natural gas, and petroleum), nuclear energy, and renewable energy sources.What is the main source of energy *? ›
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The different types of energy include thermal energy, radiant energy, chemical energy, nuclear energy, electrical energy, motion energy, sound energy, elastic energy and gravitational energy.What are the 7 main energy sources? ›
- Solar energy.
- Wind energy.
- Hydro energy.
- Tidal energy.
- Geothermal energy.
- Biomass energy.
- Oil – 39% Accounting for approximately 39% of the global energy consumption, oil has historically been the world's most used energy source. ...
- Gas – 22% Gas consumption grew at an average rate of 2.4% in the last ten years. ...
- Nuclear energy – 4.4%
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Primary energy sources take many forms, including nuclear energy, fossil energy -- like oil, coal and natural gas -- and renewable sources like wind, solar, geothermal and hydropower.What is energy sources and examples? ›
Sources of energy
Examples are solar (from the sun), wind, water, geothermal (from the earth) and biomass (from organic materials). Non-renewable energy sources don't replenish, and are formed when prehistoric plants and animals died and were gradually buried by layers of soil rock.