Transformation of Energy Through Digestion Lab

Physical and Chemical Changes http://www.youtube.com/watch?v=gCbqjs-pqJo

Energy Transformations Energy transformation is the process of changing energy from one form to another. Energy transformations take place constantly around us. Radiant energy from the sun is converted to chemical energy by plants; chemical energy in gasoline is converted to mechanical energy when our cars move; and our own digestive system converts our food into energy.

Today, we are going to focus on our digestive system converting chemical energy in our food, into chemical, thermal and mechanical energy in our bodies.

Digestion involves both physical and chemical changes Digestion involves both physical and chemical changes. During digestion, the chemical energy found in our food can be converted to many different forms. The chemical energy in food can be converted to another form of chemical energy when it is stored as glucose or fat. It can be converted to thermal energy because our body produces heat when digesting our food. The chemical energy in our food can also be converted to mechanical energy in the form of muscle movement.

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Materials beef liver Scissors Beaker thermometer 75 mL hydrogen peroxide (H2O2) stopwatch gloves goggles cracker

Safety

Procedure 1. Break your cracker into two pieces. 2. Take one half and break it apart in your hand. Is this a physical or chemical change?____________________ 3. Now, take the other half of the cracker and chew it well. Don’t swallow right away. You should taste a slight saltiness then after the cracker is well chewed, it should taste sweet. Is this a physical or chemical change? ________________

Procedure 4. Create a data table to record initial temperature and six temperatures taken at 30 second interval.

Procedure 5. Pour 75mL of hydrogen peroxide into the beaker. 6. Place the thermometer in the beaker of hydrogen peroxide. Record the initial temperature. 7. Place the liver pieces in the beaker of hydrogen peroxide.

Procedure 8. Record the temperature every 30 seconds for three minutes and write it down on your chart. 9. Clean Up –Pour off the hydrogen peroxide and dispose of it according to your teacher’s instructions. Remove the liver from the bottom and throw it in the trash can. 10. Wash your hands thoroughly.