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Lab 8: Temperature During Melting

Refer to the Beyond Labz application to find the lab bench and the Beyond Labz landing. Follow the instructions on the Beyond Labz worksheet specific to the lab title in order to complete this assignment.

Download the Beyond Labz worksheet for this lab here:

Temperature During Melting.pdf

Purpose

To determine how temperature changes as ice is heated and becomes liquid water

Intuition
Have you ever sat and watched the ice melt in your cup in the summer? Or watched as you melted butter or chocolate while baking? Phase changes are not actually that interesting to watch, are they? Nothing seems to happen for a long time as you see both phases simultaneously together. Then when all of the solid material has finally melted, the liquid can finally heat up!

Definitions

Melting Point, Calorimeter

Context & Theory
Depending on the temperature, most substances can exist as both a solid and a liquid. A substance in its liquid state has more thermal energy than it has in its solid state. The temperature at which a substance changes from a solid to a liquid is the melting point of the substance. The melting point is a characteristic property of a substance. Chemists often use the melting point to help identify or classify a substance.
 

Second lab

Lab 9: Molecular Motion & Thermal Energy

Refer to the Beyond Labz application to find the lab bench and the Beyond Labz landing. Follow the instructions on the Beyond Labz worksheet specific to the lab title in order to complete this assignment.

Download the Beyond Labz worksheet for this lab here:

Molecular Motion and Thermal Energy.pdf

Purpose

To calculate the amount of kinetic energy in a system and observe what happens when the system is given more energy.

Intuition
What do you feel when you touch a hot frying pan? What do you feel when you sit down on your car seat when your car has been sitting in the sun? What do you feel when you pick up a plastic cup full of hot water? These are examples of how you notice thermal energy.

Definitions

Kinetic Energy; Thermal Energy

Context & Theory
All matter contains atoms, which move randomly throughout the substance. These atoms have kinetic energy. Some objects are rigid solids, so the atoms aren’t as free to move around, but the atoms still have the potential to move and, in fact, are moving slightly. The total potential and kinetic energy of an object make up its thermal energy

Name ___________________________________________ Date ______________________ Class ________________________ To calculate the amount of kinetic energy in a system and observe what happens when the system is given more energy. What do you feel when you touch a hot frying pan? What do you feel when you sit down on your car seat when your car has been sitting in the sun? What do you feel when you pick up a plastic cup full of hot water? These are examples of how you notice thermal energy. Kinetic energy, thermal energy All matter contains atoms, which move randomly throughout the substance. These atoms have kinetic energy. Some objects are rigid solids, so the atoms aren’t as free to move around, but the atoms still have the potential to move and, in fact, are moving slightly. The total potential and kinetic energy of an object make up its thermal energy. 1. What will happen to the energy of the atoms in a system when you add more energy to it? 1. Start Virtual Physical Science and select Molecular Motion and Thermal Energy from the list of assignments. The lab will open in the Mechanics laboratory. 2. The laboratory will be set up with 10 balls which represent molecules inside of a substance. The system is enclosed by a box and thus the energy is conserved. You will see that the atoms are in random motion. The kinetic energy of the substance is calculated by adding up the kinetic energies of all the particles that make it up. 3. Click the green Start button to start the balls in motion. Click the Pause button to stop the balls after a few seconds. You will need to record the mass of each ball and the velocity of each ball. You can find the mass of the balls in the Parameters Palette under Objects. Record the data in the table below. Record the velocities of each of the balls. The number of the ball that is currently being tracked is located in the bottom right of the screen. Use the arrows to scroll through each ball and record its total velocity in the first data table. This value is located at the bottom of the screen in the first row, second column (vtot). Using the formula for Kinetic Energy =1/2m·v2, where m is the mass and v is the velocity, calculate the kinetic energy for each ball and record the total in the last column. Name ___________________________________________ Date ______________________ Class ________________________ Ball Number Mass (kg) 1 10 2 20 3 10 4 15 5 5 6 1 7 100 8 200 9 7 10 1000 Velocity (m/s) Kinetic Energy (J) Total Kinetic Energy 4. Now place the plunger onto one of the balls in any direction you choose. Do not reset the lab. Click the Force button to fire the plunger. This will add energy to the system. After a few seconds and a few bounces, click the Pause button. Use the table below to record the data for the new energy level of the system. Ball Number Mass (kg) 1 10 2 20 3 10 4 15 5 5 6 1 7 100 8 200 9 7 10 1000 Velocity (m/s) Total Kinetic Energy Kinetic Energy (J) Name ___________________________________________ Date ______________________ Class ________________________ 5. Repeat step 4 again, hitting one of the balls with the plunger and adding more energy to the system. Record the data in the last data table. Ball Number Mass (kg) 1 10 2 20 3 10 4 15 5 5 6 1 7 100 8 200 9 7 10 1000 Velocity (m/s) Kinetic Energy (J) Total Kinetic Energy 6. Go back and calculate the total kinetic energy for the system at the different energy levels. This is done by adding the individual kinetic energies together. Use the bottom cell in the column on the right to record the total energy. 1. Which energy level had the highest total kinetic energy? 2. If this were representing a molecule, made up of many different atoms, at which energy level would it be the most effective to use to heat up another molecule? Why? 3. How could this model be used to represent energy transfer within a molecule? Name ___________________________________________ Date ______________________ Class ________________________ To determine how temperature changes as ice is heated and becomes liquid water. Have you ever sat and watched the ice melt in your cup in the summer? Or watched as you melted butter or chocolate while baking? Phase changes are not actually that interesting to watch, are they? Nothing seems to happen for a long time as you see both phases simultaneously together. Then when all of the solid material has finally melted, the liquid can finally heat up! Calorimeter, melting point Depending on the temperature, most substances can exist as both a solid and a liquid. A substance in its liquid state has more thermal energy than it has in its solid state. The temperature at which a substance changes from a solid to a liquid is the melting point of the substance. The melting point is a characteristic property of a substance. Chemists often use the melting point to help identify or classify a substance. 1. Start Virtual Physical Science and select Temperature During Melting from the list of assignments. The lab will open in the Calorimetry laboratory. A coffee cup calorimeter filled with an ice/water mixture is on the lab bench. The ice has just been placed in the cup, so the temperature of the water is initially lowering as the ice cools the water down. The ice water is being stirred and as time passes the ice will begin to melt as the cup heats up. You will analyze the graph of the temperature to determine when the melting occurs. Click the clock on the wall labeled Accelerate to accelerate the laboratory time. 2. Observe the temperature of the ice/water mixture graphed in the plot window as a function of time until the blue graph line reaches 4 minutes. Click Save on the Plot window. Click on the link in the Lab Book to display the graph for the time 0-4 minutes. 1. What phase or phases of water are in the calorimeter at 0°C? 2. In the graph on the next page, make a sketch of what you observed of the temperature of the water as a function of time. Refer to the saved graph in the Lab Book if needed. Label the axes and label on the line where the water is a solid and where the water is a liquid. Name ___________________________________________ Date ______________________ Class ________________________ 3. What is the state, or phase, of the water at 3 minutes? 4. What happens to the temperature during the time when ice is still present in the water? Explain. 5. What happens to the temperature after all of the ice has melted? Why? 5:05 1 < Notes ... Heavenlove178@gmail.com Heaven178