Thermodynamics lab experiments

A lab report on

Specific Heat of Metals

Course:

MENG-407 Thermodynamics

Students:

xxxxxxxx

Fall 2020

1. Introduction

Metal objects have the ability to hold and transferee heat to its surroundings. This is known as specific heat. The specific heat of metals changes from one object to another. We used the specific heat in order to calculate the heat transferee of the metal object to its surroundings.

2. Experiment and Measurements

· Measure mass of the first metal object and place it inside boiling water.

· Fill 200 ml beaker with cold water and measure its temperature.

· Measure temperature of boiling water.

· Carefully remove the metal from boiling water and slowly place it inside the beaker.

· Keep stirring the water and reading its temperature until the temperature does not increase; record the equilibrium temperature. Make sure the thermometer does not touch the metal object or beaker. 

· Use the first law of thermodynamics to find the specific heat of the metal. 

· Find the amount of entropy generated during this process.

 

3.      Results and Discussion

Object 1 (Zinc):

· weight in grams = 71.0 

· weight in kilograms = 0.071

· mass of water in grams = 192.08

· Initial temperature of water (TW) = 25.8 Celsius

· Temperature of boiling water (TM) = 99.1 Celsius

· Equilibrium Temperature (Te) = 27.6

· Specific Heat of water = 4.1787 kJ/kg*K

In order to calculate the specific heat of Zinc we used the following formula:

Cm =

Cm = 0.2845 kJ/kg*K

Actual Specific Heat of Zinc = 0.39 kJ/kg*K

Percentage error:

(0.2845 - 0.39) / 0.39 *100 = 27%

To find the amount of Entropy generated we used the following formula:

= mwcw In + mmcm In

= 28.3 Btu/R

Object 2 (Brass):

· weight in grams = 71.29

· weight in kilograms = 0.07129

· mass of water in grams = 192.08

· Initial temperature of water (TW) = 27.6 Celsius

· Temperature of boiling water (TM) = 99.1 Celsius

· Equilibrium Temperature (TE) =29.3

· Specific Heat of water = 4.1816 kJ/kg*K

In order to calculate the specific heat of Zinc we used the following formula:

Cm =

Cm = 0.2744 kJ/kg*K

Actual Specific Heat of Brass = 0.38 kJ/kg*K

Percentage error:

(0.2744 - 0.38) / 0.38 *100 = 27%

To find the amount of Entropy generated we used the following formula:

= mwcw In + mmcm In

= 24.17 Btu/R

Possible errors:

· It is very possible that the Thermometer came in contact with the metal object or the beaker.

Once we obtained our calculated values for the specific heat for both objects and compared them with the actual values there was about 27% error for both experiments. However, we believe that this experiment helped us demonstrating the objectives of this lab and the concept of specific heat of metals.

References

1. Moran, M. J. (2014). Fundamentals of engineering thermodynamics. Hoboken, NJ: Wiley.