Required practical - electrolysis of aqueous solutions

• What is the process of electrolysis used for?

  To break down electrolytes to form elements using electricity
• What can be predicted from a given electrolyte during electrolysis?

  The products of electrolysis
• What is a hypothesis in the context of an investigation?

  • A starting point for investigation
  • An idea or explanation to be tested
  • Backed up by scientific knowledge
• What is the scientific question that starts an investigation into electrolysis?

  What are the products of electrolysis of aqueous solutions?
• Why is a non-metal produced at the positive electrode during electrolysis?

  Because non-metal ions are negative
• What happens to solutions that include ions of metals low in the reactivity series during electrolysis?

  They produce the metal at the negative electrode (not hydrogen)
• What prediction can be made in the hydrolysis of copper chloride?

  The product at the positive electrode will be chlorine
• What points should be addressed in planning an electrolysis investigation?

  • Which apparatus to use and a setup diagram
  • Which solutions to test
  • How to test for and identify products
  • Consideration of hazards, risks, and precautions
• What is the role of the positive electrode in an electrolysis setup?

  It is connected to the positive terminal of a dc power pack
• How many solutions should be tested in an electrolysis investigation?

  At least five solutions
• What are some suitable solutions for testing in electrolysis?

  Copper sulfate, copper chloride, sodium chloride, sodium nitrate, sodium bromide
• How can gases produced during electrolysis be collected?

  In test tubes that are stoppered
• What is the test for hydrogen gas produced in electrolysis?

  A lighted splint goes out with a squeaky pop
• What is the test for oxygen gas produced in electrolysis?

  A glowing splint relights
• What is the test for chlorine gas produced in electrolysis?

  Damp blue litmus paper turns red and is then bleached white
• What should be examined carefully after electrolysis?

  The electrodes to see if a metal has been deposited on them
• What are the hazards associated with copper sulfate solution?

  It causes skin irritation and serious eye irritation
• What precaution should be taken when handling copper sulfate solution?

  Wear gloves and eye protection
• What is a potential hazard when using a dc electricity supply in electrolysis?

  Electric shock
• What precaution should be taken to prevent electric shock during electrolysis?

  Make sure electrodes do not touch and switch off the electricity supply before handling
• What should be done to prevent harm from chlorine gas produced during electrolysis?

  Ensure small quantities are produced and work in a well-ventilated laboratory
• What should be included in a results table for an electrolysis investigation?

  • Electrolyte
  • Observations at positive electrode, including gas test results
  • Observations at negative electrode, including gas test results
• Why is it vital to make observations carefully during an electrolysis experiment?

  To record them in detail at the time they are made
• What should be considered when analyzing the results of an electrolysis experiment?

  Are there any patterns in the results and do they support the original hypothesis?
• What points should be addressed in the evaluation of an electrolysis practical?

  • Do the results agree with predictions?
  • Reasons for any differences
  • Actions taken to achieve accurate results
  • Possible improvements to the method