Food as EnergyFood as Energy

Section BSection B

Intro to Lab Activity B.1Intro to Lab Activity B.1

Food as EnergyFood as Energy

All human activity requires All human activity requires Burning food for energyBurning food for energy

Not really burnedNot really burned Energy is released by chemical Energy is released by chemical

rxn’srxn’s

How can we Tell??How can we Tell??

Figuring how much Figuring how much energy…energy…

How to determine How to determine amount of energyamount of energy

1.1. Burn a known amount Burn a known amount of foodof food

2.2. Carefully measure Carefully measure quantity of thermal quantity of thermal energy releasedenergy released

=CALORIMETRY=CALORIMETRY

Calorimeter is the Calorimeter is the device we use!!!device we use!!!

Units of EnergyUnits of Energy

ccaloriealorie Thermal energy needed to raise the temp. of 1 Thermal energy needed to raise the temp. of 1

gram of water 1 degree Celsiusgram of water 1 degree Celsius

CCaloriealorie 1000 calories1000 calories Increases the temperature of 1kg of water by 1 Increases the temperature of 1kg of water by 1

degree Celsiusdegree Celsius

1,000 calories (cal) = 1 kilocalorie(kcal) = 1 Calorie 1,000 calories (cal) = 1 kilocalorie(kcal) = 1 Calorie (Cal)(Cal)

Importance of CaloriesImportance of Calories

Nutritionists Nutritionists Count CaloriesCount Calories

DietingDieting

Comparing foodsComparing foods

Where does food energy Where does food energy originate?originate?

All food energy comes from sunlightAll food energy comes from sunlight

Plants capture solar energyPlants capture solar energy Make large energy rich moleculesMake large energy rich molecules Energy converted to chemical Energy converted to chemical

energyenergy

We recover this energy when we eat We recover this energy when we eat plants or animals that eat these plants or animals that eat these plantsplants

So Why is this all Important?So Why is this all Important?

Determine energy given off by a peanut when it burnsDetermine energy given off by a peanut when it burns

Oil in peanuts burns fast whenOil in peanuts burns fast when

Your peanut will heat a known mass of waterYour peanut will heat a known mass of water

You will measure the temp of the water before and You will measure the temp of the water before and afterafter

Then you will calculate the thermal energyThen you will calculate the thermal energy

From that we can determine the calories in that From that we can determine the calories in that peanut!!peanut!!

Page 239-241 Page 239-241 Food Energy in A PeanutFood Energy in A Peanut