Acids, bases and salts

• When an acid is added to water, the hydrogen ion (H+) is released into the solution
• An acid is defined as a proton donor
• The dissociation of a strong acid involves full dissociation
• A base is defined as a proton acceptor
• Magnesium hydroxide is the base used to treat acid indigestion
• Alkalis are bases that can dissolve in water to form aqueous hydroxide ions
• Amphoteric substances are substances that can act as both acids and bases
• When acids react with carbonates, the products formed are salt, carbon dioxide, and water
• A salt is a compound formed when the hydrogen ion (H+) of an ion is replaced by a metal ion or positive ion
• When acids react with metal oxides, the products formed are salt and water
• When acids react with alkalis, the products formed are salt and water
• When acids react with metals, the products formed are salt and hydrogen
• The products are the same when acids react with alkalis or metal oxides because both alkalis and metal oxides are types of bases
• Ammonium salts are formed when acid reacts with aqueous ammonia
• Hydrated crystals are a crystalline structure containing water
• Anhydrous crystals refer to a crystalline form that contains no water
• A dot formula indicates the amount of water present in a crystalline structure
• The methods to carry out a titration include:

  • Using a pipette, measure the volume of a solution
  • Add the solution into a conical flask and add an indicator into it
  • Add the other solution into a burette and record the volume
  • Slowly add the solution in the burette into the conical flask
  • Swirl the mixture continuously until the end point is reached
  • Repeat until concordant results are obtained
• The colour of methyl orange in an acid is red, in a base is yellow, and at the end point is orange
• Definition of a salt is when the H+ ion of an acid is replaced by a metal ion or an ammonium ion (NH4+)
• what is the name of the reaction when an acid and base reacts?

  Neutralisation reaction
• A weak acid is an acid that partially disassociates in an aqueous solution
• A strong acid is an acid that fully disassociates in an aqueous solution
• An example of a weak acid is ethanoic acid (CH3COOH), which only partly dissociates in water.
• An example of a strong acid is hydrochloric acid (HCl) which dissociates completely in water.
• Acidic solutions have a low pH value
• Alkaline solutions have a high pH value
• pH scale measures how acidic or alkaline a substance is
• The pH scale measures the concentration of H+ ions in a substance or solution
• What is a monoprotic acid?

  An acid that can donate only one proton (H+ ion) per molecule.
• A diprotic acid is an acid that can donate two protons (H+ ions) per molecule.
• Polyprotic acids are acids that can donate more than two protons (H+ ions) per molecule.
• What is a triprotic acid?

  An acid that can donate three protons (H+ ions) per molecule.
• What is produced when ammonium reacts with acid?

  Ammonium reacts with acid to produce ammonium salts but no water is produced.
• What colour is phenolphthalein at low pH?

  Colorless
• What colour is phenolphthalein at high pH?

  Pink
• What are the steps of preparing a standard solution?

  Measure, dissolve, dilute, and mix.
• What method is used for weighing precisely?

  Weighing by difference
• How can you ensure no solid is left behind when preparing a standard solution?

  Rinse beaker with distilled water
• what are concordant results?

  results that are within 0.1 cm3 of each other