2023

• Carbon dioxide is soluble in water and forms an acidic solution.an ion makes this solution acidic

  hydrogen
• Name an indicator that could be used to test the solution is acidic

  INDICATOR-blue litmus paper

  RESULT-turns red
• $H_2O$


  is a liquid cus it is waterrr
• acid and base(or alikali)

  neutralisation reaction
• What happens to sodium atoms and to oxygen atoms when sodium react with each other to produce sodium oxide($NA_2O$)


  Sodium atoms lose 1 electron.&oxygen gains 2 electrons so 2 sodium atoms to one oxygen atom to form a full outer shell
• when soidum burns in a gas jar of oxygen

  There is a yellow flame

  & sodium melts
• Give 2 different observations if potassium is used instead of sodium

  -potassium burns with lilac flame

  -and burns faster
• lithium

  is red

  and fizzes slowly

  forms lithium hyrdroxide
• orger of dicovery

  electron-----$>$proton----$>$neutron
• Why does sodium chloride not conduct electricity

  ions are in fixed place and are free to move around
• to inert electrodes

  carbon/graphite
• contain atoms in hexagonal rings

  fulllerenes and graphene
• why copper allow conduc of thermal energy

  delocalised electrons move through the structure & transfer energy
• Why does CuO have a high melting point

  strong electrostatic forces of attraction between the oppositely charged ions so a large amount of energy is needed to break/overcome the forces
• why does water have low melting point


  small molecules with weak forces between the molecules so little energy needed to overcome the intermolecular forces
• Why pH Increases During Electrolysis of Sodium Chloride Solution:

  • Water molecules break down to form H⁺ and OH⁻ ions.
  • H⁺ ions are attracted to the negative electrode and are reduced to hydrogen gas.
  • This happens because hydrogen is less reactive than sodium, so it is discharged.
  • As H⁺ ions are removed, more OH⁻ ions remain, causing the pH to increase (solution becomes more alkaline).
• Method to Investigate Volume of CO₂ from Calcium Carbonate and HCl:

  • Measure a stated mass of calcium carbonate using a balance.
  • Measure a fixed volume of hydrochloric acid using a measuring cylinder.
  • Add the acid to a conical flask containing the calcium carbonate.
  • Fit the flask with a stopper and delivery tube connected to a gas syringe.
  • Record the volume of carbon dioxide gas produced over time.
  • Repeat the experiment using different masses of calcium carbonate.