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Electrolysis term 2 lss ace


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Electrolysis term 2 lss ace

  1. 1. Electrolysis Han Ming Xuan 1P1 (9)
  2. 2. Purpose of Experiment <ul><li>Science should be all about enjoying the learning process. </li></ul><ul><li>Electrolysis is used not rarely but very commonly in our daily lives. Hence my interest in this chapter in chemistry. My goal here is to hopefully complete an experiment on electrolysis at home with only household appliances, at the same time share my interest with others. </li></ul>
  3. 3. Fundamentals first… Subatomic particle with +ve charge, resides with nucleus Subatomic particle with –ve charge Subatomic particle with no net electric charge Basic unit of a chemical element
  4. 4. An atom <ul><li>Electrons: black circle </li></ul><ul><li>Protons: red circle </li></ul><ul><li>Neutrons: : blue circle </li></ul><ul><li>Nucleus: red + blue </li></ul>
  5. 5. What is Electrolysis?
  6. 6. An electrolytic cell <ul><li>The general apparatus for a setup on electrolysis is called an electrolytic cell </li></ul>
  7. 7. Uses of Electrolysis <ul><li>Electroplating-covering a metal surface with another metal so that it will be more durable etc. </li></ul>
  8. 8. Uses of Electrolysis <ul><li>Electrorefining…purification of metals (e.g. copper) </li></ul>
  9. 9. Uses of Electrolysis <ul><li>… extraction of reactive metals such as aluminium </li></ul>
  10. 10. Uses of Electrolysis <ul><li>Manufacturing of chemicals like chlorine, sodium chloride and bleach </li></ul>
  11. 11. Fun fact <ul><li>When electrolysis is being used to plate an object with metal, it is sometimes possible to reverse the process and remove the plating! </li></ul>
  12. 12. Basics of Electrolysis References: Chemistry Insights ‘O’ Level 2 nd Edition
  13. 13. What is the Anode? Attracted to
  14. 14. What is the Cathode? Attracted to
  15. 15. Other basic terms
  16. 16. What is an oxide? <ul><li>A binary compound of oxygen with another element or group. </li></ul>Nitrous Oxide N 2 O Iron oxide Fe 2 O 3 Magnesium Oxide MgO
  17. 17. History Of Electrolysis
  18. 18. Humphry Davy Place of birth: Cornwall, England Date of Birth: 17 th December 1778 Passed away: 29 th May 1829 (age 50) Who is he?: English chemist
  19. 19. Brief account
  20. 20. Michael Faraday Country of Birth: South London Date of Birth: 22 September 1791 Passed away: 25 August 1867 (75 years old) Who is he? : Chemist and Physicist who contributed significantly to the study of electromagnetism and electrochemistry.
  21. 21. Short Bibliography
  22. 22. Faraday’s Law of Electrolysis <ul><li>1 st Law </li></ul><ul><li>+The amount of chemical change during electrolysis is proportional to the electrical charge(measured as coulomb C) passed. </li></ul><ul><li>2 nd Law </li></ul><ul><li>+The charge required to deposit or liberate a mass m is given by Q=Fmz/M , where F is the Faraday constant - symbol F, has the value 9.6485309(29)x10 4 , z the charge of the ion, and M the relative ionic mass. </li></ul>
  23. 23. Redox reactions
  24. 24. Oxidation {gain oxygen, lose hydrogen} <ul><li>Oxidation is the gain of oxygen and the loss of hydrogen. </li></ul><ul><li>An oxidising agent is a substance that gives oxygen to/takes hydrogen from another substance. </li></ul><ul><li>E.g. burning of coal(rapid), rusting of iron(slow) </li></ul>
  25. 25. Reduction {lose oxygen, gain hydrogen} <ul><li>Reduction is the loss of oxygen or the gain of hydrogen </li></ul><ul><li>We say that a substance has been reduced when it goes through reduction. </li></ul><ul><li>A reducing agent is a substance that gives oxygen to/takes hydrogen from another substance. </li></ul><ul><li>E.g. extraction of metals </li></ul>This process can include both of the redox reactions. All extraction of metals by heating metal oxides with carbon are redox reactions.
  26. 26. Experiment No.1
  27. 27. Apparatus <ul><li>Small hinge (anode) </li></ul><ul><li>Iron nail (cathode) </li></ul><ul><li>Sodium Chloride solution (electrolyte in aqueous solution) </li></ul><ul><li>1 pair of gloves </li></ul><ul><li>Battery holder with batteries </li></ul><ul><li>Crocodile clips </li></ul><ul><li>Spare bowl of fresh water, to rinse off the ‘reaction’ from the electrodes. </li></ul>
  28. 28. Anode (+ve) <ul><li>Oxidation(occurs at the anode) causes the gold plated hinge to turn red (iron oxide: iron in contact with oxygen) </li></ul>
  29. 29. Anode after 5 days <ul><li>Slow oxidation occurs </li></ul>
  30. 30. Cathode (-ve) <ul><li>Reduction(occurs at the cathode) causes the iron nail to turn black </li></ul>
  31. 31. Cathode after 5 days <ul><li>Corrosion occurs </li></ul>
  32. 32. Electrolyte <ul><li>Chemical reaction </li></ul>
  33. 33. Explanation
  34. 34. Electrolysis of Sodium Chloride
  35. 35. Dangers <ul><li>Through the research that I did, I can create 2 very dangerous gases by just using household appliances. </li></ul>Hydrogen gas(H) Chlorine gas (Cl)
  36. 36. Actual result <ul><li>Electrolysis of sodium chloride solution. Copper as electrodes, sodium chloride as electrolyte. </li></ul>
  37. 38. Chlorine
  38. 39. Cl=Chlorine gas <ul><li>Stays close to the ground and spreads rapidly(heavier than air) </li></ul><ul><li>Has a pungent and irritating odour </li></ul><ul><li>Used in WW1 as a choking agent </li></ul><ul><li>Strong oxidiser, react with explosive chemicals(turpentine and ammonia) and produce explosive compounds. </li></ul><ul><li>When it comes into contact with moist tissues (eyes, lungs, throat), it changes into hydrochloric and hypochlorous acid (bleach) . </li></ul>
  39. 40. Cl=Chlorine gas <ul><li>(ppm= parts per million) </li></ul><ul><li>0.3 ppm : Detectable by measuring devices </li></ul><ul><li>3 ppm : Detectable by smell </li></ul><ul><li>30 ppm : Coughing and vomiting </li></ul><ul><li>60 ppm : Lung damage </li></ul><ul><li>≈ 1000 ppm : Death </li></ul>
  40. 41. Symptoms of exposure <ul><li>Coughing </li></ul><ul><li>Chest tightness </li></ul><ul><li>Burning sensation in the nose, throat, and eyes </li></ul><ul><li>Watery eyes </li></ul><ul><li>Blurred vision </li></ul><ul><li>Nausea and vomiting </li></ul><ul><li>Burning pain, redness, and blisters on the skin if exposed to gas, skin injury similar to frostbite if exposed to liquid chlorine </li></ul><ul><li>Difficulty breathing or shortness of breath (may appear immediately if high concentrations of chlorine gas are inhaled, or may be delayed if low concentrations of chlorine gas are inhaled) </li></ul><ul><li>Fluid in the lungs (pulmonary edema) within 2 to 4 hours </li></ul>
  41. 42. What to do when exposed ? <ul><li>Remove clothing and wash you body with large amounts of soap and water (to protect person from any chemicals on body) </li></ul><ul><li>Seal all contaminated clothing in 2 layers of plastic bags </li></ul><ul><li>Clothing that must be removed over the head should be cut from the body </li></ul>Do not freak out, stay calm
  42. 43. Hydrogen
  43. 44. Dangers <ul><li>Hydrogen gas(H 2 ) is colourless, odourless and flammable. </li></ul><ul><li>A mixture of hydrogen and air can be highly explosive . </li></ul><ul><li>Hydrogen leaking into external air may spontaneously ignite . </li></ul>Like a non-luminous flame, hydrogen fire is almost invisible, which can lead to accidental burns.
  44. 45. Experiment No.2 Electrolysis of Sodium Bicarbonate solution
  45. 46. Result of experiment <ul><li>Overall view </li></ul><ul><li>Center: Electrolyte </li></ul><ul><li>Side: Anode and Cathode </li></ul>
  46. 47. Anode (+ve) <ul><li>Copper pipe </li></ul>Before After
  47. 48. Cathode (-ve) <ul><li>Iron nail plated with copper </li></ul>Before After
  48. 49. Sodium Bicarbonate What is it made up of ?
  49. 50. Bicarbonate Ion <ul><li>HCO 3 - </li></ul>
  50. 51. Sodium Ion Na +
  51. 52. What happened?
  52. 55. Other References <ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul>