Calorimeter (Jesus Ojeda)
Title: Keep Burning those Calories
Principle(s) Investigated: Calorie, kilocalorie, food, heat, temperature, joules, Mass, weight,
Standards: Explain the importance of variety and moderation in food selection and consumption. (1.3.N)
Describe dietary guidelines, food groups, nutrients, and serving sizes for healthy eating habits. (1.4.N)
Materials: marshmallow, macadamia nuts, thermometer, aluminum soda can, Ring stand, paper clips , lighter,
Procedure: The beginning of the lesson will begin with questions regarding what the students know about a Calorie, calorie and a kilocalorie. Some students might already have an understanding of what a calorie does to a person but the intention of this lesson is to go in depth on what a calorie really is and to demonstrate that eating habits and calorie intake are linked with each other. The experiment requires students to burn snacks and record temperature change, using water, in a test tube. In order to determine what snack, we combusted, has the most calories. Students will use the calorimeter results to determine what snack possesses the most kinetic energy or in this case calories. The teacher will also discuss what foods are considered healthy in terms of calories and why is it important to look for the nutritional information on food labels. The majority of teenage students love to eat junk food so the intention of the lab is to get them informed to how many calories some of their favorite snacks have by using calorimetry.
Student prior knowledge: Before starting the lesson, the students should know the following terms. Students should know the difference between calorie and Calorie but if they forgot then the teacher must revisit the material. Students should also know the specific heat of water, the rate at which the water absorbs energy, which is 4.184J/g °C. Students should also know that 1ml of water equals out to 1 gram.
Explanation: The lesson will begin with an introduction to keywords and followed by an attempt to relate the material to student’s lives. By relating the lesson to the student they will have an easier time understanding the rest of the experiment. The instructor must review for students who do not know.
- Calorie is also known as a kilocalorie and food Calorie
- Calorie (kilocalorie) = 1000 calories
- calorie = a unit of heat energy and the energy needed to raise the temperature of 1 gram of water through 1 °C (now usually defined as 4.1868 joules).
- 1 calorie = 4.1868 joules
Teacher should discuss what calories have in relation to a heat energy.
- fundamental first law of thermodynamics states that energy cannot be created or destroyed but it can be transferred from one kind to another. So in this case, calories from a snack can be made into energy that humans can use if humans eat it the snack. If we were to light a snack such as a macadamia nut on fire, then it would stay lit on fire for a certain amount of time in relation to the amount of calories it had.
Ultimately, your body weight is dependent only on the difference between the amount of calories that you consume versus the amount of calories that you burn off.
Students will need to answer questions on the live quick write on the excel document in order to assess whether or not they understand the material. Students will make predictions and they will also make calculations in order to solve the equations provided for the lab. Students will work in groups of 5 and use the calorimetric technique in an attempt to measure the kinetic energy stored in the snacks. The teacher can use common snacks to show how much calories they have. Then the instructor can start asking questions such as, what does excess calories consumed do? What does high calorie content say about a snack? How can we find out how much is in a tiny piece of food? We cannot measure potential energy but we can get the temperature of kinetic energy. In this case, kinetic energy of a snack can be measured by burning it. The thermometer measurements of the water show how much energy was released by the snack, when combusted.
Q = Potential Energy (Joules) which is the amount of energy the water absorbs.
times
M = mass of water (g)
times
S = specific heat of the water or at the rate in which the water absorbs energy (4.18 J/g °C)
times
ΔT = tempt change of water using a thermometer (°C)
The instructor must also mention that the heat gained by the water comes from the energy stored in the snack, if the experiment is done properly. Students should understand this concept before attempting to measure the calorie content of the snacks.
Q system = -Q surroundings
DATA TABLE
M = ______________ g
Initial Temperature = ________________ °C
Final Temperature = ________________ °C
Tf – Ti = ΔT
ΔT = ________________ °C
Questions and Answers:
Before the teacher can assess how well the students understood the initial lesson, the teacher must scaffold step-by-step in order to make sure the students do not fall behind. This experiment will require students to use a method called calorimetry, which will require the use of food and combust it in order to heat water and record the temperature change.
Quickwrite.
1. If you combust a Hot Cheetoe weighing 1.00 gram and the heat absorbed by the water made the temperature rise to 45°C from an initial temperature of 23°C. How much energy does the Cheetoe have?
Students should be aware that in order to solve the problem, they would need to solve by using the measurements given in the problem. They will need to input the measurements for the variables within the formula. Students must also be reminded that the specific heat capacity of water is 4.18J / g°C. Based from the prompt, students should be able to decipher that:
Q(joules)=m*s*ΔT
M = Mass of the Cheetoe = 1.00 g
S = Specific heat of water = 4.18 J/g°C.
ΔT = change in temperature = 45 – 23 = 22 °C
Now that we can fill in the calorimetry equation, we solve for Q. Q represents the amount of energy stored in the snack in joules.
Q = 1.00g * 4.18J/g°C * 22°C
Q= 91.96 J
2. You combust a piece of pepperoni, weighing 1.50 gram, and the heat absorbed by the water increases the temperature of the water to 55°C when the initial temperature was 24°C. In this situation how many energy
did the pepperoni have?
Q(joules)=m*s*ΔT
M = Mass of the Cheetoe = 1.50 g
S = Specific heat of water = 4.18 J/g°C.
ΔT = change in temperature = 55 – 24 = 31 °C
Now that we can fill in the calorimetry equation, we can figure out how much kinetic energy was stored in the pepperoni.
Q = 1.50g * 4.18J/g°C * 31°C
Q= 194.37 J
3. After doing these basic practice exercises, Students should have a better understanding of the lab and what it entails. Students will be required to use calorimetry in order to figure out what snack possesses the most calories.
Students will be provided with the materials necessary to figure out the calculations. The instructor will be responsible in providing the snacks that everyone will measure. Questions will be posted on a excel quick write that will be available on the link below.
https://docs.google.com/spreadsheets/d/1bCxtUHVOeKL6JnJzO7MZQLr7gUwfdcF0uCWe7I5rVos/edit?usp=sharing
4. In the process of using calorimetry, what kind of reaction is occurring? What is the outcome from this reaction? How does it help us figure out the calorie count of the snack.
When using calorimetry, we are essentially allowing the kinetic energy stored in the snack to escape when we combust it. We use the water to measure just how much kinetic energy was released in joules. This also gives us the calorie content of the snack as well.
Reference
Herr, Norman. Hands-On Chemistry Activites with Real-Life Applications. P 358-359
http://www.unit-conversion.info/energy.html Unit conversions
http://www.algebralab.org/activities/activity.aspx?file=science_caloriecontent.xml