Acids.

• What is an acid?

  An acid is a substance that donates hydrogen ions (H+) in a chemical reaction.
• What is an Alkali?

  A type of chemical compound that is soluble in water and has a pH greater than 7. It produces Hydroxide ions (OH-).
• A neutral solution has a PH of 7. An acidic solution has a PH of less than 7. An alkaline solution has a PH of more than 7.
• What is the effect of acids on litmus, methyl orange, and phenolphthalein indicators?

  Litmus: Turns red in acidic solutions. Methyl orange: Turns red in acidic solutions. Phenolphthalein: Turns colorless in acidic solutions.
• What is the effect of Alkalis on litmus, methyl orange, and phenolphthalein indicators?

  Alkalis turn litmus blue, methyl orange yellow, and phenolphthalein pink.
• The higher the concentration of hydrogen ions in an acidic solution, the lower the pH; and the higher the concentration of hydroxide ions in an alkaline solution, the higher the pH.
• As hydrogen ion concentration in a solution increases by a factor of 10, the pH of the solution decreases by 1.

  
• How to investigate the change in PH of a solution?

  • Pipette fixed HCl volume, add 1 spatula CaO or Ca(OH)₂, and swirl.
  • Record pH after the base reaction.
  • Repeat for 1-10 spatulas, keeping HCl volume constant; record results in a neat table.

  
• Dilute solutions have a low concentration of solute, while concentrated solutions have a high concentration of solute.
• What is a strong acid?

  An acid that completely dissociates in water to produce hydrogen ions.
• What is a weak acid?

  An acid that only partially dissociates in water and has a low concentration of hydrogen ions. They tend to have a reversible reaction.
• What is AAWS?

  Acid + Alkaline --> Water + salt.
• What is an alkaline?

  A soluble base.
• Acid + metal --> salt + Hydrogen
• Acid + metal hydroxide --> Salt + water.
• What is CAWCS?

  Metal carbonate + Acid --> Water + carbon dioxide + Salt.
• What is MASH?

  Metal + Acid --> salt + metal hydroxide.
• What is the chemical test for hydrogen?

  squeaky pop test.
• what is the chemical test for carbon dioxide?

  Lime water test (The water turns foamy).
• What is a neutralisation reaction?

  A chemical reaction between an acid and a base that forms a salt and water.
• If soluble salts are prepared from an acid and an insoluble reactant, the excess reactant is added to ensure that all of the acid has been reacted. The excess reactant is then removed to ensure that the products produced are only salt and water.
• titration is used to precisely control the amount of reactants, and careful mixing of the acid and soluble reactant in the correct proportions ensures a complete reaction, leaving only the desired soluble salt and water in the solution.
• What is the method for titration?

  1. Titration:

  • Measure acid with a pipette, add indicator.
  • Titrate with alkali until color change signifies neutralization.

  1. Neutralization Reaction:

  • Repeat reaction with same volumes but no indicator. It should go from pink to colourless.

  1. Product Isolation:

  • Solution after reaction contains only salt and water.
  • Evaporate water, let solution crystallize.

  1. Salt Collection:

  • Filter and dry to obtain pure, dry salt.
• all common sodium, potassium and ammonium salts are soluble
• all nitrates are soluble
• common chlorides are soluble except those of silver and lead
• common sulfates are soluble except lead, barium and calcium
• common carbonates and hydroxides are insoluble except those of sodium, potassium and ammonium
• What is the method used to make insoluble salts (precipitation reaction)?


  1. Mixing Solutions:

  • Combine solutions of soluble salts containing cation and anion of the insoluble salt.

  1. Formation of Precipitate:

  • Observe the formation of a solid precipitate, the insoluble salt.

  1. Filtration:

  • Separate the precipitate using filtration.

  1. Washing:

  • Wash the collected solid with water to remove impurities.

  1. Drying:

  • Air dry or gently heat the washed precipitate.

  1. Collection of Pure Salt:

  • Obtain a pure, dry sample of the insoluble salt.
• What is the effect of alkalis on litmus, methyl orange, and phenolphthalein indicators?


  Litmus: purple. Methyl orange: yellow. phenolphthalein: pink.
• Nitrate: all soluble

  Chloride: all soluble except Ag+ and Pb2+ (acronym - CAP)

  Sulfate: all soluble except Ca2+, Ba2+, Pb2+ (mnemonic - Sweet Couple Buying Pyjamas)

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  oxide, hydroxide, carbonate: all insoluble except G1 elements & NH4+