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

• 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.