Name:_______________________________Date:_______________Time:____________

Course:_________________

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A. Specific Heat

Purpose: To determine the specific heat of metals by calorimetry.

Apparatus: Calorimeter and accessories, metal objects, temperature sensor, PC w/interface, electronic balance, hot plate, beaker, and thread.

Theory:

In this experiment the metal object will be heated in hot water (temperature = T_H) and transferred to the calorimeter cup with water. The rise in temperature will be measured with a temperature sensor. In order to calculate the specific heat you need to derive an expression for the specific heat of the metal, C_m in terms of measurable quantities. 

1. Write down an expression for the heat loss by the metal object = _____________________

(Use the following measurable quantities: M_m = mass of the metal object, C_m = specific heat of the metal object,  T_H = temperature of the hot metal, and T_f = final temperature of water).

2. Write down an expression for the heat gain by water = __________________________

(Use the following measurable quantities: M_w = mass of water, C_w = specific heat of water, T_f = final temperature of water, T_i = initial temperature of water).

3. Write down an expression for the heat gain by the calorimeter cup = _____________________

(Use the following measurable quantities: M_c= mass of the calorimeter cup, C_c= specific heat of the calorimeter cup, T_f = final temperature of water, and T_i = initial temperature of water).

Equating Heat loss by metal to Heat gain by water & cup will give an expression for, C_m:

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Procedure:

1) Fill the beaker with water (about 2/3 full), place it on the hot plate, and bring the water to boil.

2) Find the mass of the metal object.

3) Find the mass of the calorimeter cup. Get some tap-water (about 1/2 full) in the cup and find the mass of the cup with water.

4) Set the calorimeter cup inside the calorimeter jacket and close the lid.

5) Lower the metal object into the boiling water by means of a thread. Be sure the cylinder is completely immersed and not to touch the bottom of the beaker. You need to hold the metal in the hot water for about 2-3 minutes.

6) While you are holding the metal in the hot water, (until procedure 9) let your partner measure the temperature of the hot water, and follow procedures 7 & 8.

To measure temperature: Open "DataStudio", select "Create Experiment", scroll down the sensors and        double-click temperature sensor. Double-click Digits Display and click "start".  

7) Remove the temperature sensor and let it cool down for about 2 minutes.  

8) Place the temperature sensor inside the calorimeter cup and record the temperature of the water, T_i , to the nearest tenth of a degree.

9) Transfer the metal object from the hot water, quickly to the calorimeter cup. Stir the water and watch the temperature until the temperature peaks and starts to drop. Record this peak temperature. (T_f)

10) Calculate the specific heat and compare it with the accepted value.

11) If the % error is high consult the instructor.

12) Repeat procedures 2-11 for other metal objects, using fresh tap-water each time.

13) Write a conclusion.

DATA:

Specific heat of the calorimeter cup material = C_c =__________cal/gm.C⁰

Specific heat of water = 1 cal/gm.C⁰

mass of the calorimeter cup = M_c =_________gm.

Conclusion: (about 1/3 of a page)

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Purpose: To determine the latent heat of fusion of ice by the method of calorimetry.

Apparatus: calorimeter with jacket, warm-water, ice cubes, temperature sensor, PC w/interface, and, electronic balance.

Theory:

In this part ice (mass M_i) will be added to a calorimeter cup (mass M_c) with water ( mass M_w).

Follow the following steps and derive an expression for the latent heat of fusion of ice, L_f .

1. Write down an expression for the heat gain by the ice:

Heat gain, by the ice = _______________________________________ 

(Use the following measurable quantities: M_i - mass of ice, L_f - latent heat of fusion of ice, C_w - specific heat of water, and T_f - final temperature of water).

2. Write down an expression for the heat loss by the calorimeter cup:  

Heat loss, by the calorimeter cup = ____________________________________

(Use the following measurable quantities: M_c- mass of the calorimeter cup, C_c- specific heat of the calorimeter cup, T_i- initial temperature of water, and T_f - final temperature of water).

3. Write down an expression for the heat loss by water:

Heat loss, by the water = _____________________________

(Use the following measurable quantities: M_w- mass of the water, C_w- specific heat of the water, T_i- initial temperature of water, and T_f - final temperature of water).

Equating the heat gain and heat loss will give an expression for L_f :

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Procedure:

Trial-1:

1) Record the room temperature, using your thermometer.

2) Find the mass of the calorimeter cup.

3) Fill the calorimeter cup 2/3 full of room temperature water and find the mass of the calorimeter with water.

4) Place the calorimeter cup with water in the calorimeter jacket and put on the lid. Record the temperature of the water, T_i, to the nearest tenth of a degree.

5) Go to Kinard 12 with the calorimeter, get an ice tray from the freezer compartment of the refrigerator, and add a cube of ice  to the water. Bring the calorimeter back and insert the temperature sensor to the cup. Watch the temperature while stirring and record the minimum temperature reached, T_f. Make sure the ice cube is melted.

6) Find the mass of the calorimeter cup, water, and melted ice.

7) Compute L_f and its percent error.

Trial-2: For trial-2 we need to use warm-water with a specific temperature. To find this specific temperature we need to use the change in temperature from trial-1 and the current room temperature. 

    Temp. of warm water = room temp. + ½ (change in temperature from trial-1).

8) Repeat 3-7 with warm water of the above temperature.   

9) Write a conclusion.

DATA