Topic: heat measurment

EXPERIMENT 3: Matter and Temperature Change

The best place to start this experiment is in a steam sauna; a confined room where heat lostto its surroundings is minimized.

 

Water poured directly over hot stonesabsorbsa tremendous amount of heat causing vaporization and increasingthe air

 

temperature dramatically. This type of heat transfer can be quantified; howeverthe temperature change is highly dependent on

 

the intrinsic property called specific heat capacity.

 

 

 

 

Allmatteris composed of individual particles in constant motion, colliding with one another;at any particular moment,

 

regardless of the velocity of any individual particle, the kinetic energy (Ek) of the entire system remains constant. The

 

average Ek of all particles in a system corresponds directly to the temperature. Addition of heat causes increased Ek which

 

is observable as an increase in temperature. A thermometer is an efficient tool capable of quantifying the average Ek of a

 

system. When heat is gained or lost by a substance the temperature of the substance changes in accordance with the following

 

relationship so long as no phase change occurs.

Placing one hot object in contact with a cold object allows heat to flow from the hot object to the cold object until both

 

are in thermal equilibrium. Affecting a temperature change as heat is absorbed are both the objects mass and the materials

 

specific heat capacity (C). Specific heat capacity is defined as the quantity of heat needed to raise the temperature of 1

 

gram of substance by 1oC. This value varies widely amongst elements and compounds.

In a substance that absorbs heat, Q is positive and a substance that releases heat, Q is negative. When heat transfer occurs,

 

the quantity that is lost equals the quantity absorbed.

 

Efficient heat transfer occurs only in an isolated system lest outside energy transfer occurs. This can be effectively

 

created in a calorimeter, a device capable of quantifying heat by measuring a change in temperature of an isolated reaction.

 

Thus, if the material and mass are known and temperature change is measured and heat quantified.

 

Experimental

Objective: Measure temperature changes to determine specific heat capacity.

 

Part A – Before starting an experiment, parameters should be known to the best expect an outcome. Before carrying this

 

experiment out, make a prediction of what the final temperature is expected to rise.

Procedure

1)         Weigh a quantity of a known metal that will easily fit in the coffee cup calorimeter.

2)         Place the metal back in the freezer for 10 minutes. Record the freezer temperature.

3)         Place 100 mL of deionized water in a coffee cup calorimeter (left). Record the temperature.

4)         Predict the final temperature before transferring the metal.

5)         Transfer the metal to the calorimeter and immediately cap.

6)         Observe the temperature and record the lowest temperature observed. Compare to your predicted value.

Part B – Here an unknown metal is added to known quantity of water at a known temperature. Accurate identification of the

 

unknown is accomplished byquantifying temperature change andcalculating specific heat capacity.

 

1)         Weigh a quantity of the unknown metal small enough to easily fit in the Styrofoam cup.

2)         Place this known metal in the freezer 10 minutes. Record freezer temperature.

3)         Transfer 100 mL of room temperature, deionized water in a Styrofoam cup; record the exact volume and temperature.

4)         Deliver the water into a Styrofoam coffee cup and measure temperature.

5)         Deliver the unknown metal to the Styrofoam cup and cover.

6)         Record the lowest temperature observed.

7)         Calculate the specific heat capacity and identify the unknown metal.

 

 

Part C:Properlyidentify a liquidfrom temperature change.

1)         Place 50 mL of each of the 2refrigerated liquids into identical, 100 mL beakers

2)         Place a thermometer into each liquid and watch the temperature rise for15 minutes.

3)         Observe the temperature change and determine which bottle is water and which is alcohol

 

Name:

Section:           ¬

EXPERIMENT 3: Report Sheet

 

Part A

Parameter       Water  Metal

Volume (mL)              N/A

Mass Metal (g)

Specific Heat Cap. (J/g•oC)

Ti (oC)

Predicted Tf (oC)

Observed Tf (oC)

Heat Transferred (J)

Metal Name

 

Part B

Parameter       Water  Metal

Volume (mL)               N/A

Mass (g)

Initial T (oC)

Final  T (oC)

Specific Heat (J/g•oC)

Unknown metal

Part C: Liquid A:                                              Liquid B:

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