pH scale and indicators

• What is acid in water?

  An acidic solution
• What is a base in water?

  An alkaline solution
• What is pure water?

  Neutral
• What are indicators?


  Substances that change colour when added to acidic/alkaline solutions
• What are the three categories of the pH scale?

  Acid, neutral and alkali
• What do the red and orange colours of the pH scale indicate?

  Strong acid
• What do the yellow and light green colours show in the pH scale?

  Weak acid
• What does green indicate on the pH scale?

  Neutral
• What does light blue show on the pH scale?

  Weak alkali
• What does dark blue and purple show in the pH scale?

  Strong alkali
• What are the numbers that indicate acid on the pH scale?

  0-6
• What number represents neutral on the pH scale?

  7
• What numbers represent alkali on the pH scale?

  8-14
• What does a strong acid do more than weak acid?

  Fizz, float and move
• Are pH values lower in strong acid than weak acid?

  Yes
• Is the rate of reaction lower in strong acids than weak acids?

  No
• Does strong or weak acid have a higher temperature rise than the other?

  Strong
• What do acidic solutions release in solution?

  H+ ions
• What are some examples of strong acids?

  • Hydrochloric
  • Nitric
  • Sulfuric
• What are some examples of weak acids?

  • Ethanoic
  • Citric
  • Carbonic
• What do alkali solutions contain?

  OH- ions
• What are some examples of strong alkalis?

  • sodium hydroxide
  • potassium hydroxide
• What are some examples of weak alkalis?

  • Ammonia
  • Ammonium hydroxide
• What is a neutralisation reaction?

  When an alkali is added to an acid to neutralise it
• What is the neutralisation reaction?

  H+ + OH- -> H2O
• What is a dilute acid?

  Acid molecules mixed with a large amount of water
• What is a concentrated acid?

  Little to no water molecules mixed with acid