SCI403B/404B: Physics | Unit 4 | Lessons 3 and 4: Laboratory: Specific Heat Laboratory Instructions Laboratory: Specific Heat Materials Supplied Student Guide Laboratory Guidelines graduated cylinder – 250 mL foam cups with lids – 2 thick rubber band scale, digital thermometer, advanced stirring rod slotted weight set, steel Also Needed plastic bag – small household objects – freezer compartment distilled water – 100 mL Advance Prep (3 days) Review the list of materials for the lab prior to the lesson, because there are several items that you must supply. Safety Review the Laboratory Guidelines before conducting the lab. Experiment Setup Collect your materials and assemble the calorimeter according to the following steps: 1. Place a rubber band around one cup. This will allow that cup to fit snugly inside a second cup without touching the bottom of the outer cup. It will also isolate the inner cup from the surrounding air. 2. Place the inner cup inside the outer cup. Label this assembly Cup 1. 3. Punch two small holes in the cup lid so that you can put a thermometer and the stirring rod snugly through them. 4. Make a data table like Table 1. © 2010 K12 Inc. All rights reserved. Copying or distributing without K12’s written consent is prohibited. Page !1 of ! 3 SCI403B/404B: Physics | Unit 4 | Lessons 3 and 4: Laboratory: Specific Heat Table 1: Data and Observations of the Specific Heat of Unknown Substance Observations Trial 1 Trial 2 Trial 3 Mass of Cup 1, empty (g) Mass of water, calculated (g) Beginning temperature of water in Cup1 (°C) Combined mass of metal masses (g) Beginning temperature of masses = measured temperature of freezer (°C) Final temperature of water in Cup 1, measured (°C) Change of water temperature, calculated (°C) Change of temperature of masses, calculated, positive value (°C) Procedure 1. Measure and record the mass of Cup 1 empty without the lid. 2. Put 70 mL of distilled water into Cup 1. 3. Measure the mass of Cup 1 plus the water, without the lid. Subtract the mass of Cup 1 empty from this number to obtain the mass of the water. Record that information in the table. 4. Obtain two 50 g slotted masses and record their combined mass in the table. Place the masses in the plastic bag. 5. Insert the thermometer and the stirring rod into the lid and place the lid over Cup 1. 6. Record the initial temperature of the water. Remove the thermometer. 7. Place the thermometer in the refrigerator’s freezer compartment. After 5 minutes, remove the thermometer and record the temperature. This will be the initial temperature of the masses. 8. Place the bag containing the masses in the freezer and let it sit for 30 minutes so that it is the same temperature as the freezer. 9. When the masses have the same temperature as the freezer, remove the bag, then remove the masses from the bag and place them in Cup 1. Put the lid back on and place the thermometer through the hole in Cup 1. 10. Gently swirl the calorimeter to mix the water inside Cup 1. 11. After the temperature has not changed for at least a minute, record the final temperature of the water inside Cup 1. 12. Empty the water from Cup 1 and repeat Steps 1–11 two more times. You may use the same masses, but replace the water inside Cup 1 for each trial. Dry the masses thoroughly after each use. © 2010 K12 Inc. All rights reserved. Copying or distributing without K12’s written consent is prohibited. Page !2 of ! 3 SCI403B/404B: Physics | Unit 4 | Lessons 3 and 4: Laboratory: Specific Heat 13. Calculate the specific heat of masses (Cm) by using the following equation: mmCmΔTm + mwCwΔTw = 0 where • mm is the mass of the masses (g) • mw is the mass of the water (g) • Cm is the specific heat capacity of the masses J g !°C • • Cw is the specific heat capacity of water, 4.18 ΔTm is the temperature change of the masses (°C) • ΔTw is the temperature change of the water (°C) Remember to solve the equation algebraically for Cm before substituting in the values of the other variables. 14. Repeat Step 13 for each trial and average the values. Analyze Answer the questions in the Lab Report thoroughly. © 2010 K12 Inc. All rights reserved. Copying or distributing without K12’s written consent is prohibited. Page !3 of ! 3
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