PHYS 1405 – Conceptual Physics I
Heat and Temperature
Materials
LabPro
Heat Pulser
Immersion Heater
Stainless temperature probe
Styrofoam cup, large
Styrofoam cup, small
Introduction
In this activity we will explore the connection between heat and temperature. Our procedure will be to add heat in equal increments to a beaker of water and measure the effect on the temperature.
Safety
In this lab we will make use of immersion heaters. Immersion heaters must be immersed in water before they are plugged in. If you plug them in without first immersing them, they will glow red hot and possibly melt, presenting a considerable risk of burning you and also of possibly starting a fire. Be sure to have the immersion heater plugged in only during the indicated times during the procedure. Also, always make sure that the immersion heater is not immersed beyond the bottom of the plastic handle. (You want it in the water but not too much!)
Procedure
Q1. Use the electronic balance to determine the mass of the small styrofoam cup. Fill the cup with about 100 ml of water and record the mass again. Determine the mass of the water in the cup.
mass of Styrofoam cup: _______________
mass of Styrofoam cup + water: ________________
mass of water: _______________
Set-up
Do not plug in the
immersion heater until instructed to do so.
Place the coil of the immersion heater into the water. Water should not go above the plastic handle on the immersion heater. Make sure that the LabPro has power and is connected to the laptop using one of the USB ports in the back of the laptop. Plug the heat pulser into DIG/SONIC 1 on the LabPro and connect the stainless temperature probe into CH 1 on the LabPro. Plug the 120 V cord connected to the heat pulser into an outlet.
Open LoggerPro 3.1 and click on
the open icon 
and open the experiment file by following the
path Probes & Sensors=> Heat Pulser=>Heat Pulser 5s.
In this experiment file, in addition to the normal Collect button, you will also have a button which says Pulse. Each time you click on the pulse button, it will turn the heater on for 5 s.
Verify that the immersion heater is immersed correctly into the water and then plug the immersion heater into the outlet on the heat pulser.
Click on the Collect button and LoggerPro will start to record the temperature of the water. Use the stainless steel temperature probe to stir the water continually during this procedure.
Measure the initial temperature of the water until it reaches a steady value, and then click on the Pulse button one time. The heater will turn on for 5 s. Observe the temperature. It should go up for 5 s or so and then maintain a steady value. Once the temperature has reached a steady value, click on the pulse button again. Keep repeating this procedure for 10 pulses or until the experiment stops. Remember to continually stir the water. Unplug the immersion heater at this point.
Data Analysis
Click on the Examine button 
. When it is selected, as you scroll over the
data, a box will appear which gives you the Temperature and time for each data
point. Record the initial temperature of
the water before the first pulse was clicked.
Record it in the data table below in the row for step 0. Move the cursor to a data point where the
temperature has reached a steady value after the first pulse ended. Record the value of the temperature in the
row for step 1. Repeat until you have
obtained the temperature after each pulse.
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Step |
Temperature (C°) |
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0 |
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2 |
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5 |
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9 |
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10 |
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In the table below, record the change in temperature after each input of heat. For instance DT1 = T1 – T0, DT2 = T2 – T1, etc
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Step # |
DT |
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1 |
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2 |
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10 |
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Q2. When you clicked on the Pulse button the heater turned on for 5 s. If the power rating of the heater is 120 W, how much energy was given off by the heater?
Q3. Where did that energy go?
Q4. Heat is defined as a flow of energy form a hotter object to a cooler one. Assuming no losses to the beaker or the air, how much heat was added to the water during each pulse?
Q5. Was the temperature change roughly constant for each pulse of heat added?
Q6. Did a constant amount of heat input produce a constant temperature change?
Q7. How is the amount of heat added related to the change in temperature?
Q8. If instead of adding heat, we removed heat. What would be the effect on the temperature?
Determine the mass of the large Styrofoam cup and then fill it with 200 ml of water.
Q9. Determine the mass of the water in the cup.
mass of Styrofoam cup: _______________
mass of Styrofoam cup + water: ________________
mass of water: _______________
Verify that the immersion heater is immersed correctly into the water and then plug the immersion heater into the outlet on the heat pulser. Repeat the procedure and data analysis that you conducted previously for the new amount of water.
Record your temperature readings in the table below.
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Step |
Temperature (C°) |
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0 |
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1 |
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2 |
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3 |
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4 |
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5 |
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6 |
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7 |
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8 |
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9 |
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10 |
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In the table below, record the change in temperature after each input of heat. For instance DT1 = T1 – T0, DT2 = T2 – T1, etc
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Step # |
DT |
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1 |
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2 |
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3 |
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4 |
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5 |
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6 |
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Q10. Was the temperature change still
roughly constant for each input of heat?
Q11. How did the size of the temperature change compare when you had twice as much water compare to the size of the previous temperature change.
Q12. When you had twice the volume of water, how much more mass of water did you have in the cup?
Q13. What type of relationship do your answers to Q11 and Q12 suggest exists between the change in temperature and the mass?
We have seen that the temperature went up a roughly a constant amount each time a pulse of heat was added. Further, the amount the temperature went up was less for more mass and greater for less mass. We can combine these observations into a single formula relating heat mass and temperature change.
Heat = constant x mass x Change in temperature. It is customary to use the letter Q to denote the heat, so in symbols the formula becomes
Q = c×m×ΔT. The constant is known as the specific heat and is a property of the material that you are studying.
From our data, we can determine the specific heat for water. We will do so for each set of data.
Q14. From you first data set determine ΔT from before the first pulse was added to after the last pulse was added. ΔT = __________
Q15. You added 600 J of heat in each pulse, so what was the total amount of heat added from all of the pulses?
Q16. What was the mass of the water used in the first data set in kg?
Q17. Plug in your values into the formula Q = c×m×ΔT and solve for the specific heat of water. Include units.
Q18. Repeat you calculation of the specific heat for the second set of data.
ΔT = ________ °C
m = ________ kg
Q = _________ J
Q19. Did you obtain values for the specific heat which were close to each other for each set of data?
Q20. The accepted value of the specific heat of water is 4196 J/(kg C°). Were your values close to this value?