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Aashima Singh

on 3 July 2014

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Transcript of Energy

Group 4 Project
Organic material as cells
Burning Potato
Burning crisps
Heated potatos giving off energy
By Imad, Leah, Luca and Aashima
Biological aspect
Chemical aspect
Physical aspect
Biological aspect
Chemical aspect
Physical aspect
Did not work --> The potato did not catch fire
Why did it not work?
Biological aspect
Chemical aspect
Physical aspect
Organisms store energy chemically
Chemical Energy = The energy stored within bonds
• Peeled the potatos
• Cut the potatos into 10g pieces
• Heated water bath to 70°
• Dropped 6 potato pieces into water bath and started count down timer
• Put 200ml of tap water into the beakers and measured initial temperatures
• At count down timer alarm, took out the potatos using gloves or tongs then dropped them into the beaker
• Noted down maximum temperature the water in the beaker reached with a thermometer
• Repeated for various amounts of time (2,4,6,8,10 and 12 minutes)

peeled potatos
cut potato into10g slice
Set up a stand with clasp
Put test tube with 10ml water with a thermometer in the clasp of the stand
Set up a bunsen burner under the test tube (20cm away)
Measured initial temperature of the water inside the test tube
Turned on bunsen burned and held 10g potato slice above it using tongs
Watched potato burn
noted down temperature of water after potato completely burnt

Batteries convert chemical energy into electricity
2 different metals:
Redox reaction between acid (citric acid/ phosphoric acid) and nail
Zinc loses electrons to acid
--> More positive
Copper in penny reacts with the acid
Copper loses H+ ions (protons) to acid
--> More negative
This creates a circuit
• Set up stand with test tube with water and a thermometer
• Measured initial temperature of the water inside the test tube
• Weighed the individual crisps
• Set crisp on fire using a lighter, then heated the water using the burning crisp
• noted down the maximum temperature of water in the test tube
• Washed the test tubes and repeated experiment 20 times with many different masses of crisps

Because potatoes have a very high water content
Water is not flammable, and thus prevents the potato from catching fire
Non-water parts burn, but water prevents flame from continuing on
Water is not flammable:
Burning (combustion) are reactions between a chemical and oxygen
Water is already oxidised hydrogen
Reaches Thermal Equilibrium: no net transfer of energy between parts of the system.
constant temperature
While potato is heated
The movement of the water molecules is transferred to the molecules in the potato, causing it to also have more movement --> More energy
While potato is giving off heat
The movement is given from the potato to the water
Unsuccessful lemon battery
Successful lemon battery
burnt potato slice
Again due to organisms chemically storing energy
Because organisms are solely complex assortments of molecules --> Have a lot of chemical bonds/ energy
Organisms store energy, in order to use when energy is less abundant and to pass along
potato slices in water bath
During chemical reactions, some bonds are formed, while others are broken
Breaking of bonds releases energy
Forming of bonds uses energy
During combustion, macromolecules are converted into very small molecules (Carbon dioxide and water)
More bonds are broken than formed
A lot of energy is given off
heated potato slices in beakers
Electrochemical cell: converts chemical energy into electrical energy
Transfer of electrons between the zinc nail and copper coin
opposites attracts each other
generates current
The longer the potatoes were heated, the more energy they stored
Therefore more heat is transferred to the water
The final water was not a closed system --> Heat escaped
There was no comparison.
Experiment would have been more informative, if the heat capacity of potatoes had been compared to other vegetables
Water temperature rose at different rates
The weight has little effect on how much electricity is produced
The metals are also important in the production of electricity, and they were kept constant
Loss of electricity due to high resistance
There is a proportional relationship between the mass and energy released
Because it the amount of chemical bonds created and broken are proportional depending on mass
It was not a closed system --> A lot of energy was lost to the surroundings
In our first attempt, we tried to eliminate that, but this lead to there being too little Oxygen
Energy transfer: heating transferred by a temperature difference
making all particles move faster in random directions
Organisms need to maintain a fairly constant temperature, due to the fact that otherwise their enzymes do not function --> No chemical reactions can be carried out
Therefore, organisms should be insulated enough to not be affected by fluctuations in external temperatures too much
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