acids, alkalis and salts

• What do acids form in water?

  Acidic solutions
• What do acids produce in aqueous solution?

  Hydrogen ions, H+
• What do alkalis form in water?

  Alkaline solutions
• What do alkalis produce in aqueous solution?

  Hydroxide ions, OH-
• What is the pH value of alkaline solutions?

  Greater than 7
• What is a neutral solution?

  A solution that is neither acidic nor alkaline
• What is the pH value of acidic solutions?

  Less than 7
• What is the pH value of a neutral solution?

  7
• What does the pH scale measure?

  • Measures acidity or alkalinity of a solution
  • Can be measured using a pH probe or universal indicator
• What are the colours of red and blue litmus paper in different pH conditions?

  • Red litmus paper: stays red in acidic, stays red in neutral, turns blue in alkaline
  • Blue litmus paper: turns red in acidic, stays blue in neutral, stays blue in alkaline
• What is a base?

  A substance that reacts with an acid to form a salt and water
• What are bases that are soluble in water called?

  Alkalis
• What happens when a base is insoluble in water?

  It is not classified as an alkali
• What is a neutralisation reaction?

  A reaction between an acid and a base
• What do acids in solution provide?

  Hydrogen ions, H+
• What do alkalis in solution provide?

  Hydroxide ions, OH-
• What is produced in an acid-alkali neutralisation reaction?

  Water
• What is the ionic equation for the neutralisation reaction?

  H+(aq) + OH-(aq) → H2O(l)
• What is produced when acids react with metals?

  A salt and hydrogen
• What is the general equation for the reaction of an acid with a metal?

  Acid + metal → salt + hydrogen
• What are the products of the reaction of hydrochloric acid with magnesium?

  Magnesium chloride and hydrogen
• What type of reactions are the reactions of acids with metals?

  Redox reactions
• What is the ionic equation for the reaction of magnesium with hydrochloric acid?

  2H+(aq) + Mg(s) → Mg2+(aq) + H2(g)
• What happens to magnesium atoms during the reaction?

  They lose electrons and are oxidised
• What happens to hydrogen ions during the reaction?

  They gain electrons and are reduced
• What are the products when an acid reacts with a metal oxide?

  • Salt
  • Water
• What are the products when an acid reacts with an alkali?

  • Salt
  • Water
• What are the products when an acid reacts with a carbonate?

  • Salt
  • Water
  • Carbon dioxide
• What is the first part of a salt's name derived from?

  The base, alkali, or metal carbonate
• What does hydrochloric acid produce?

  Chloride salts
• What does nitric acid produce?

  Nitrate salts
• What does sulfuric acid produce?

  Sulfate salts
• What is the formula of aluminium sulfate?

  Al2(SO4)3
• What are the steps to make a soluble salt from an insoluble reactant?

  1. Add powdered insoluble reactant to acid until in excess
  2. Filter to remove excess solid
  3. Heat the solution to evaporate water
  4. Leave to crystallise
  5. Dry the crystals
• What is a solution?

  A mixture formed when a solute dissolves in a solvent
• What is the concentration of a solution?

  A measure of how 'crowded' the solute particles are
• What is a dilute solution?

  A solution with a relatively small amount of dissolved solute
• What is a concentrated solution?

  A solution with a relatively large amount of dissolved solute
• What happens to strong acids in solution?

  They completely dissociate into ions
• What happens to weak acids in solution?

  They only partially dissociate into ions