ZIMSEC O Level Combined Science Notes: Introduction to acids

  • A lot of everyday materials are acidic
  • This means that they contain an acid
  • Examples of everyday materials that contain acids are:
  • Lemons and other citric fruits as well as materials that contain these for example Orange crush
  • Vinegar (contains ethanoic/acetic acid)
  • Battery acid (sulphuric acid)
  • Other acids include: dilute sulphuric acid, dilute hydrochloric acid etc

Common properties of acids

Acids turn litmus paper red

Acids turn litmus paper red

  • They have a sour taste (you should never taste/ingest sulphuric and hydrochloric acids as they are very toxic)
  • They fizz/effervesce when mixed with bases such as sodium hydrogen carbonate
  • They turn litmus paper red
  • They turn Universal Indicator red, orange or yellow
  • They cause iron to rust and dissolve
  • They react with metals eating them away
  • This is called corrosion
  • Acids are corrosive
  • Some metals do not react with acids
  • For example copper and hydrochloric acid do no react
  • Such metals are said to be resistant to corrosion
  • Metals react with acids at different rates
  • Metals such as magnesium that are higher up in the reactivity series react much more quickly with acids and quickly dissolve
  • Zinc and iron react more slowly but are still corroded by acids

Acid Reactions and their word equations

  • \text{metal+acid}\rightarrow\text{ salt+hydrogen}
  • For example:
  • \text{zinc+hydrochloric acid}\rightarrow\text{zinc chloride+hydrogen}
  • Acids also react with bases
  • \text{acid+base}\rightarrow\text{salt+water}
  • For example:
  • \text{copper oxide+sulphuric acid}\rightarrow\text{copper sulphate+water}

To access more topics go to the Combined Science Notes page.