CHEMISTRY

• Salt bridge allows for the movement of ions through it
• Voltmeter is replaced by bulb = less resistance
• What is the melting point comparison between sodium bromide, sodium, and sodium iodide?

  Sodium bromide has a higher melting point
• Why does sodium bromide have a higher melting point than sodium?

  Due to ionic bonding in sodium bromide
• What type of bonding does sodium have?

  Metallic bonding
• What is the nature of the attraction in metallic bonding in sodium?

  Attraction between positive ions and delocalised electrons
• What type of structure does sodium have?

  Giant/lattice structure
• What causes the electrostatic attraction in sodium bromide?

  Attraction between oppositely charged ions
• What type of bonding is present in sodium bromide and sodium iodide?

  Ionic bonding
• How do the ionic bonds in NaBr compare to those in NaI?

  Ionic bonds in NaBr are stronger
• Why is the attraction between ions in NaBr stronger than in NaI?

  Br- ion is smaller than I- ion
• What are the key differences in bonding and structure between sodium, sodium bromide, and sodium iodide?

  • Sodium:
  • Metallic bonding
  • Giant/lattice structure
  • Sodium bromide (NaBr):
  • Ionic bonding
  • Stronger ionic bonds than NaI
  • Sodium iodide (NaI):
  • Ionic bonding
  • Weaker ionic bonds than NaBr
• Electron pairs repel to be as far as possible. Lone pair Lone pair more than Lone pair bonding pair.
• To reduce VO2^+ to VO^2+ we need a reducing agent whose electrode potential is less than VO2^+, so it can donate electrons.
• Ethanoyl Chloride is corrosive
• Why reflux is not essential when flask is heated to 85 C for 10 minutes?

  Boiling points are above 85 C
• Describe recrystallisation process used to purify aspirin

  the crude aspirin will be dissolved in small amounts of warm ethanol; of minimum volume. Filter, cool to recrystallise. Using a Büchner funnel filter under reduced pressure. Wash and dry.
• Describe 2 ways the result would show that the product is impure

  Melting point :

  Lower than data book value

  Broad melting point, wide range of temperatures it melts.
• Why is it important to use a safety pipette filler?

  To ensure safe handling of hazardous liquids
• What should you add to the volumetric flask after the oven cleaner?

  Deionised water
• What is the purpose of adding deionised water to the flask?

  To make up to the mark
• How should you stop the flask after adding water?

  Inverted to mix thoroughly
• What should you rinse the pipette with after using the oven cleaner?

  Diluted solution
• What type of flask should the diluted solution be transferred to?

  A conical flask
• 6 MARKER

  
• In titration washing the burette with water can have an impact on the titration, we would need more of the product to neutralise whatever is in the conical flask.
• Safety pipette filler
• phenolphthalein is colourless to pink
• What color is phenolphthalein in acidic conditions?

  Colorless
• What color does phenolphthalein turn in basic conditions?

  Pink
• How does phenolphthalein behave in acidic conditions?

  It remains colorless
• How does the pH of a solution affect phenolphthalein's color?

  Lower pH makes it colorless, higher pH makes it pink
• If a solution turns phenolphthalein pink, what can be inferred about its pH?

  The solution is basic
• What is the pH range where phenolphthalein changes color?

  From acidic to basic conditions
• What does an increase in pH do to phenolphthalein's color?

  It changes from colorless to pink
• What is the significance of phenolphthalein's color change in titrations?

  It indicates the endpoint of the titration
• In a titration, if phenolphthalein remains colorless, what does that indicate?

  The solution is still acidic
• What are the two functional groups present in amino acids?

  Amino group and carboxyl group
• What is the structure of an amino acid called?

  Alpha amino acid
• What is the significance of the R group in amino acids?

  It determines the specific amino acid