Energy Transfer (Ngoc Bach)

Title: Coconut Chemistry

Principle(s) Investigated: phases of matter, freezing point, melting point, temperature, heat, energy transfer, thermal energy, conduction

Standards:

Performance Expectations

• MS-PS3-4 Plan an investigation to determine the relationships among the energy transferred, the type of matter, the mass, and the change in the average kinetic energy of the particles as measured by the temperature of the sample.
• Clarification Statement: Examples of experiments could include comparing final water temperatures after different masses of ice melted in the same volume of water with the same initial temperature, the temperature change of samples of different materials with the same mass as they cool or heat in the environment, or the same material with different masses when a specific amount of energy is added.
• Assessment Boundary: Assessment does not include calculating the total amount of thermal energy transferred.

Science and Engineering Practices

• Integrate qualitative and/or quantitative scientific and/or technical information in written text with that contained in media and visual displays to clarify claims and findings.

Disciplinary Core Ideas

PS3.A: Definitions of Energy

• Motion energy is properly called kinetic energy; it is proportional to the mass of the moving object and grows with the square of its speed. (MS-PS3-1)
• A system of objects may also contain stored (potential) energy, depending on their relative positions. (MS-PS3-2)
• Temperature is a measure of the average kinetic energy of particles of matter. The relationship between the temperature and the total energy of a system depends on the types, states, and amounts of matter present. (MS-PS3-3),(MS-PS3-4)

PS3.B: Conservation of Energy and Energy Transfer

• When the motion energy of an object changes, there is inevitably some other change in energy at the same time. (MS-PS3-5)
• The amount of energy transfer needed to change the temperature of a matter sample by a given amount depends on the nature of the matter, the size of the sample, and the environment. (MS-PS3-4)
• Energy is spontaneously transferred out of hotter regions or objects and into colder ones. (MS-PS3-3)

Cross-cutting Concepts:

Energy and Matter

• MS-PS3-5 Energy may take different forms (e.g. energy in fields, thermal energy, the energy of motion).
• MS-PS3-3 The transfer of energy can be tracked as energy flows through a designed or natural system.

Materials: (Total Cost)

Supplies

• Gallon-sized Ziploc bag
• Quart-sized Ziploc bag
• Thermometer
• Measuring cup
• Cereal bowl
• Ice cubes
• Rock salt
• Gloves

Ingredients for 2-4 servings (scale up for the number of students in the class)

• ½ cup of coconut cream
• ½ cup of coconut milk
• 2 tablespoons of sugar
• ½ teaspoon of vanilla extract (may be substituted for other flavors such as cocoa powder, matcha green tea, pumpkin spice)
• Toppings are optional: sprinkles, mini peanut butter cups, shredded coconut, etc.

Procedure:

QUICKWRITE

1. Please wash your hands prior to this food science experiment.
2. Place the quart-sized Ziploc bag in a cereal bowl.
3. In the quart-sized Ziploc bag, pour all of the ingredients (i.e. ½ cup of coconut cream, ½ cup of coconut milk, 2 tablespoons of sugar, and ½ teaspoon of vanilla extract).
4. Measure and record the temperature of the mixture.
5. Seal the Ziploc securely, set aside.
6. Measure 7 cups of ice and place into the gallon sized Ziploc bag.
7. Measure and record the temperature of the ice in the bag.
8. Wear gloves to protect your hands or handle the top edges of the bag to avoid freezer burn.
9. Mix 1 cup of rock salt with the ice.
10. Measure and record the temperature of the ice and rock salt mixture in the bag.
11. Place the securely sealed quart-sized Ziploc bag into the gallon sized Ziploc bag.
12. Securely seal the gallon-sized Ziploc to prevent the contents from spilling out.
13. Shake vigorously for 8 minutes or until your mixture is solidified to the ice cream texture of your preference.
14. Measure and record the temperature of the ice cream.
15. Enjoy your cold coco-nutty treat :)

Alternative Procedures

• PBS Ice Cream Shake
• The Ice Cream Phase Change Lab
• TpT Ice Cream Experiment
• 5 Minute Ice Cream

Worksheet as requested

• Ice Cream Lab & Application Questions

Student prior knowledge:

Students understand that water occurs at three different phases. They have prior knowledge of pure water freezing below 32 degrees Fahrenheit or less than 0 degrees Celsius. Students should be able to distinguish between heat and temperature. Students should know that heat is the energy stored inside an object or matter, and the temperature is a measurement of how hot or cold something is.

Source: University of Washington

Explanation:

1. Engage: Making ice cream is a fun activity for students. Elementary, middle school, and high school students alike enjoy the easy, quick process of creating their own yummy concoction.
2. Explore: The fun factor of this experiment does not distract students from exploring the phenomenon of heat energy transfer.
3. Explain: When rock salt (or sodium chloride NaCl) is added to the ice cubes, NaCl molecules interact with the H2O molecules. This interaction initiates the melting process and lowers the freezing point. The ice-salt mixture has to absorb more energy to melt. Reiterate: the moment we add salt, the temperature of the ice drops to colder than freezing and starts absorbing heat from its surroundings. The absorption of heat is an endothermic process. As the ice melts, it conducts heat more readily in liquid form. The ice-forming-water conducts energy from the ice cream mixture faster than solid ice. Due to the energy transfer, ice cream is made without a machine.
4. Extend: This hands-on activity is an extension of prior knowledge about phases of matter, freezing point, and heat. Also, this experiment can be refined and modified. A variable that we can change is the material of the container holding the salt ice. Instead of the gallon sized Ziploc bag, we can use a stainless steel container.
5. Evaluate three methods of thermal energy transfer (conduction, convection, and radiation).

Questions & Answers:

1. What is temperature, heat, and thermal energy?
   1. Temperature is a measurement of how hot or cold an object is. Heat is the energy stored inside an object. And, thermal energy is the total internal energy of the atoms or molecules of a substance. Heat is thermal energy that is being transferred between two places.
2. How does heat travel?
   1. The transfer of thermal energy as heat requires a difference in temperature
   2. between the two points of transfer. Heat may be transferred by means of conduction, convection, or radiation. Conduction is the transfer of thermal energy (heat in transfer) due to collisions between the molecules in the object. Collisions between adjacent atoms and molecules transfer kinetic energy from the warmer to the cooler object. The objects must be in physical contact. Convection is thermal energy transferred by the flow of matter. Radiation is the transfer of energy by electromagnetic radiation. Radiation can travel in a vacuum.
3. One thing you've probably noticed about heat is that it doesn't generally stay where you put it. Hot things get colder, cold things get hotter, and given enough time, most things eventually end up the same temperature. How come?
   1. There's a basic law of physics called the second law of thermodynamics and it says, essentially, that cups of coffee always go cold and ice creams always melt: heat flows from hot things toward cold ones and never the other way around. You never see coffee boiling all by itself or ice creams getting colder on sunny days! The second law of thermodynamics is also responsible for the painful fuel bills that drop through your letterbox several times a year. In short: the hotter you make your home and the colder it is outside, the more heat you're going to lose. To reduce that problem, you need to understand the three different ways in which heat can travel: called conduction, convection, and radiation. Sometimes you'll see these referred to as three forms of heat transfer. [Sources cited: Woodford, Chris. (2009/2018) Heat. Retrieved from https://www.explainthatstuff.com/heat.html.]

Applications to Everyday Life: (Adapted from Ohio State University)

In many cases, we wish to prevent heat transfer. For example, the less heat that leaves our home in the winter, the less energy (and money) we need to keep it comfortable. In cases where we are trying to minimize the transfer of thermal energy, we must take all three kinds of heat transfer into account. To understand how to limit heat transfer by conduction, let us consider a physical model for the process, such as heat flow through a wall. We have already discussed one factor that we would expect to make a difference, and that is the material of which the wall is made. The higher the thermal conductivity of the material, the faster heat would be transferred. However, thermal conductivity is a property of the material, and we also expect the shape and amount of the material to have an effect on heat transfer. It is reasonable to expect that heat flow through a wall would increase as the area of the wall is increased and would decrease as the thickness of the wall is increased. It is also reasonable that the difference in temperature between the sides of the wall should make a difference: the greater the temperature difference, the faster we would expect the heat to flow. These expectations can be written in equation form, as shown in Equation 4.3.

In building a wall that would limit the transfer of thermal energy by conduction, we typically would have the most control over the building material and the wall thickness. Therefore, we would want to choose a material with a low thermal conductivity and make it as thick as is possible. Losses from convection can be reduced by obvious measures, such as plugging drafts and closing windows. Trapping pockets of air also prevent heat loss due to convection. Materials such as Styrofoam, fiberglass, wool, and down trap pockets of air and reduce thermal energy transfer by convection. A way to limit heat transfer by radiation is to reflect as much of the radiation as possible. This is why, for example, many thermos bottles are silvered on the inside.

Photographs: Include photos and diagrams that illustrate how the investigation is performed.

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