Chemical Changes

• What is the pH of an acid?

  pH < 7
• What is the pH of an alkali?

  pH > 7
• What is a base?

  A substance which neutralises an acid
• Are alkalis soluble or insoluble?

  Soluble bases
• What colours represent what with universal indicators?

  • Acid = Red
  • Alkali = Purple
  • Neutral = Green
• What is a neutralisation reaction?

  When an acid and a base react to produce a solution with a pH of 7
• What are the general equations for neutralisations?

  • acid + metal carbonate > salt + carbon dioxide + water
  • acid + metal oxide > salt + water
  • acid + metal hydroxide > salt + water
• How do you find the formulae of salts?

  Cross the charges of each ion