1. Experiment Number: 4 2. Date: 15/10/07 3. Title: Enthalpy change of a displacement response 4. Aims/Objective: To figure out the enthalpy modification of a displacement reaction (In between zinc and copper (II) ions) 5. Introduction: Excess zinc powder is included in a measured quantity of aqueous copper (II) sulphate. The temperature level change is then measured over a time period so the enthalpy of this reaction can be determined. 6. Pertinent Equations/Chemical Reactions Involved: Zn (s) + CuSO4(aq)?? ZnSO4(aq) + Cu(s) 7. Chemicals: 1. 00M copper (II) sulphate option 25.
0 cm3 Zinc powder (in excess) 5. 9g.
8. Device and devices: Security phenomenon x 1 Spatula x 1 25 cm3 pipette x 1 Balance x 1 Pipette filler x 1 Thermometer(0-100 oC) x 1 Polystyrene cup with cover x 1 Digital timer x 1 Weighting bottle x 1 9. Treatment: 1. An empty polystyrene cup was weighted. 2. 5. 9g of zinc powder (in excess)was weighted and after that added into the polystyrene cup. 3. The temperature of the copper (II) sulphate solution in beaker was tape-recorded every half minute for 2. 5 minutes and after that 25.
0 cm3 of the copper (II) sulphate solution was pipetted into a polystyrene cup. 4. Thermometer was put through the hole of the cover.
The solution was stirred continuously and the temperature was tape-recorded every half minute for 6 minutes. 10. Observation: The blue colour of the option vanishes. Brown strong is formed. Some zinc powder remains there. 11. Information, Calculation and Results: a. Results Table Time/min 0. 0 0. 5 1. 0 1. 5 2. 0 2. 5 3. 0 3. 5 4. 0 4. 5 Temperature/oC 25. 0 25. 0 25. 0 25. 0 25. 0 25. 0 25. 0 60. 0 73. 0 71. 0 Time/min 5. 0 5. 5 6. 0 6. 5 7. 0 7. 5 8. 0 8. 5 9. 0 9. 5 Temperature/oC 69. 0 68. 0 67. 0 65. 5 64. 5 63. 5 62. 5 61. 5 60 59 b. Calculations 1&& 2. Graph of temperature against time.
3. Energy change of solution = 25 x 10-3 x 4. 18 x (76. 5 – 25) = 5. 38175 kJ mol-1 Energy change of the cup = 2.
27 x 10-3 x 1. 3 x (76. 5- 25) = 0. 1519765 kJ mol-1 Enthalpy change for the quantities used = – (5. 38175 + 0. 1519765) = – 5. 5337265 kJ mol-1 Assumptions : (1) The specific heat capacity of the solution is the same as that of water. (2) Heat is not lost to the surrounding. 4. No. of mole of CuSO4 = 1 x 25 x 10-3 = 0. 025 mol Required enthalpy change = – [(5. 5337265)/0. 025] = – 221 kJ mol-1 Zn (s) + CuSO4(aq) ?? ZnSO4(aq) + Cu(s) ? H = – 221 kJ mol-1 12. Conclusion :
It was found that the enthalpy change of a displacement reaction (Between zinc and copper (II) ions) was – 221 kJ mol-1. 13. Answer to questions 1. % error = {[- 221 – (- 217)]/- 217 }x 100% = 1. 84% The experimental value is more negative than the accepted value. 2. Reasons : (1) Heat is lost to the surrounding. (2) The specific heat capacity of the solution is not the same as that of water. 3. CuSO4 is not in excess which is used up totally. No matter that more zinc is used or powder is very finely divided, same amount of the solution is used so there is same increase in temperature.
Remember! This is just a sample.
You can get a custom paper by one of our expert writers.
Get your custom essay
Helping students since 2015
Essay Writing Service Features
Our Experience
No matter how complex your assignment is, we can find the right professional for your specific task. Contact Essay is an essay writing company that hires only the smartest minds to help you with your projects. Our expertise allows us to provide students with high-quality academic writing, editing & proofreading services.
Free Features
Free revision policy
$10Free bibliography & reference
$8Free title page
$8Free formatting
$8How Our Essay Writing Service Works
First, you will need to complete an order form. It's not difficult but, in case there is anything you find not to be clear, you may always call us so that we can guide you through it. On the order form, you will need to include some basic information concerning your order: subject, topic, number of pages, etc. We also encourage our clients to upload any relevant information or sources that will help.
Complete the order form
Once we have all the information and instructions that we need, we select the most suitable writer for your assignment. While everything seems to be clear, the writer, who has complete knowledge of the subject, may need clarification from you. It is at that point that you would receive a call or email from us.
Writer’s assignment
As soon as the writer has finished, it will be delivered both to the website and to your email address so that you will not miss it. If your deadline is close at hand, we will place a call to you to make sure that you receive the paper on time.
Completing the order and download