(All) Required Practicals

• What is an independent variable in an experiment?

  The variable that is changed
• What is a dependent variable in an experiment?

  The variable that changes as a result
• Why do we keep control variables the same?

  To ensure accurate results
• What should you specify when measuring length?

  The equipment used for measurement
• What safety equipment should be used when working with chemicals?

  Goggles and gloves
• Why is it important to state obvious safety precautions?

  To ensure all safety measures are noted
• How can you reduce errors in measurements?

  Align your eye with the measurement
• What is a method to improve measurement accuracy?

  Take multiple readings
• What is the process for making salt crystals?

  • Heat concentrated sulfuric acid in a beaker
  • Add excess copper oxide until unreacted powder remains
  • Filter out unreacted copper oxide
  • Gently heat the copper sulfate solution in an evaporating basin
  • Crystals of copper sulfate are formed
• What is the process of electrolysis?

  • Place sodium chloride solution in a beaker
  • Insert two inert carbon electrodes
  • Connect electrodes to a power supply
  • Positive ions are reduced at the cathode
  • Negative ions are oxidized at the anode
• What happens if the cation is more reactive than hydrogen?

  Hydrogen is reduced to form H2 gas
• What gas is produced when chloride ions are oxidized?

  Chlorine gas (Cl2)
• How do temperature changes affect reaction rates?

  • Conduct reaction in a polystyrene cup
  • Measure maximum temperature with a thermometer
  • Increase volumes of alkali to observe temperature changes
  • Plot temperature against volume to find neutralization point
• What are the two practicals to observe rates of reaction?

  1. Measure gas volume produced over time
  2. Observe turbidity change in a reaction
• What is the process of chromatography?

  • Spot solution on chromatography paper
  • Draw a pencil line as a reference
  • Hang paper in distilled water
  • Allow capillary action to separate particles
  • Calculate RF values for identification
• What is the purpose of distillation in water purification?

  To obtain pure, drinkable water
• What is the titration process for neutralization?

  • Measure alkali in a conical flask
  • Add indicator to visualize pH change
  • Use a burette to add acid slowly
  • Swirl flask and observe color change
  • Calculate concentration using moles and volume
• How can metal and non-metal ions be identified?

  • Use flame tests for metals
  • Test for carbonate ions with hydrochloric acid
  • Use silver nitrate for halide ions
  • Observe precipitate colors for identification
• What color precipitate indicates chloride ions?

  White precipitate
• What color precipitate indicates bromide ions?

  Cream precipitate
• What color precipitate indicates iodide ions?

  Yellow precipitate
• What happens when hydrochloric acid is added to carbonate ions?

  Bubbles of carbon dioxide are produced
• What is the result of adding barium chloride to sulfate ions?

  White precipitate forms