chemistry

• why is diamond hard?

  Each carbon is covalently bonded to Four other carbons.

  Its a giant covalent structure.

  Covelent bonds are strong.
• Electrolysis at the cathode.

  Hydrogen is produced at the cathode if the metal is more reactive than hydrogen. If the metal is less reactive than hydrogen than the metal is produced at the cathode.
• Write down the method for the titration experiment.

  1. Fill the burette with 0.5 mol/dm3 of Hcl.
  2. Pipette 15 cm3 of NaOH solution into the conical flask and add a few drops of phenolphthalein indicator.
  3. Open the tap to release small amounts of Hcl into the conical flask, swirl gently after each addition until the solution has changed colour.
  4. Repeat the process until you get an concordant result.
• Explain why carbon conducts electricity.

  1. Each carbon is bonded to three other carbons.
  2. It has one delocalised electron.
  3. electrons move through the structure.