Calorimetry

Objectives

• Determine the number of calories in types of foods.

• Calculate the percent error between the experimental and actual value.

Calories

• Calorie: The amount of energy required to raise 1 gram of water by 1 degree Celsius

• Our cells NEED energy to function– The energy in food is converted to energy the

body can use– Calories measure how much energy the body will

get from the food

Calorimetry

• The process to measure the amount of calories in food– 1000 chemistry calories = 1 kilocalories– 1000 calories = 1 Calorie– 1 Calorie = 1 food calorie

ChartsMeasurements Sample 1 Sample 2

Food used

Mass of empty can (g)

Mass of can plus water (g)

Minimum temperature of water (°C)

Maximum temperature of water (°C)

Mass of Weigh Boat(g)

Initial mass of food (g)

Final mass of food (g)

Initial Directions• Weigh the mass of the empty can

– Record the mass• Fill the can with 50 to 1000 mL of water

– IF THE BALANCE SAYS ERROR, POUR SOME OF THE WATER OUT!• Re-weigh the can with the water

– Record the mass• Make a weigh boat from aluminum foil

– See example at the front of the room– Measure and record the mass of the weigh boat

• Choose one food sample– Weigh the mass of the food sample in the weigh boat– Initial mass of food = total mass – mass of weigh boat

• Setup the calorimetry as shown in the next slide

Directions 2

• Open Logger Pro• Click open and open the biology folder• Open the program 01Energy in Food• Connect the temperature probe using the

LabQuest mini• Change the length of the experiment to 10

minutes• DO NOT TIGHTEN THE PROBE TO TIGHTLY!!!

Directions 3

• Click the green arrow• Let the temperature run for 30 seconds

– THIS IS YOUR INITIAL TEMPERATURE• Away from the stand, let the food with the match.• Place the dish under the center of the can• ONCE THE FOOD BURNS OUT DO NOT RE-LIGHT IT

– This will ruin the experiment– Just let the experiment continue to run!!!

• If the temperature goes above 60˚C, then blow out the food– This will ruin the temperature probe

Directions 4

• Once the entire experiment is complete, click on the Stat button– Record the MAXIMUM Temperature

• Clean-up:– Throw away the dish, food samples, and cans– Put the probe, ring stand, cork, and clamps on the

back shelf• Finish the calculations

CalculationsCalculations Sample 1 Sample 2

Mass of water (g)

Change in temperature of water (°C)

Change in mass of food sample (g)

Energy gained by water (chemistry calorie)

Energy content of food sample (chemistry calorie per gram)

Energy content of food sample (food calorie per gram)

Conclusion Questions

• Which of the foods tested had the greatest energy content?

• Which of the tested foods is the best energy source? Explain your reasoning for your response.

• Why might a food with lower energy content be a better energy source than another food with higher energy content?