Enthalpy & Entropy

1805 WordsNov 4, 20128 Pages
Experiment ENTHALPY AND ENTROPY OF ZINC WITH COPPER SULFATE The CCLI Initiative Computers in Chemistry Laboratory Instruction LEARNING OBJECTIVES The learning objectives of this experiment are to. . . ! ! determine changes in enthalpy and entropy of the reaction of zinc with copper sulfate using two methods: electrochemistry and calorimetry. compare the enthalpy values obtained by the two methods. BACKGROUND Thermodynamics is concerned with energy changes that occur in chemical and physical process es. The enthalpy and entropy changes of a system undergoing such processes are interrelated by the change in free energy, ªG, according to the equation ªG = ªH - T ªS (1) This investigation focuses on the reaction Zn(S ) +…show more content…
Let the set-up stand for 15 minutes until the temperature stabilizes. 4. Pour about 5 ml of 0.1 M KNO3 into the center well. Pour about 5 ml of 0.50 M ZnSO4 into well #1 and about 5 ml of 0.50 M CuSO4 into well #2. 5. With clean tweezers, take a s trip of filter paper and dip one end into the central well (where immersion in the KNO3 solution will hold one end); dip the other end into well #1. Repeat this procedure with another strip of filter paper, dipping the other end into well #2. This creates the salt bridge for your galvanic cell. 6. With clean tweezers take a zinc metal strip and sand it (on a piece of paper so as not to scratch the table top) to remove any oxide coating. Bend 2 cm of one end of the ªS trip and immerse it in the ZnSO4 solution (well #1). The rest of the metal strip (3cm) extends out to the edge of the cell and should be bent over the rim. Repeat the same procedure with the copper metal strip and place it in well #2. Later the electrical leads (alligator clips ) from the interface will be attached to the metal strips. 7. Fasten your temperature probe to the ring stand with a clamp and adjust the temperature probe such that its tip can be immersed in the central well (KNO3 solution) of the cell. It is assumed that the temperature of the ZnSO4 solution and CuSO4 solution will be very close to the temperature of the KNO3 solution throughout the experiment. 8. Start the computer program to
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