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Chapter 8 Acids and Bases:

Points to Note:

  • The most common laboratory acids are:

  1. Sulfuric Acid

  2. Nitric Acid

  3. Hydrochloric Acid

 

  • The most common laboratory bases are:

  1. Sodium Hydroxide

  2. Calcium Hydroxide

 

  • A solution of calcium hydroxide in water is known as limewater

Neutralisation:
Left: This is how hydrochloric acid would be commonly stored in a laboratory
 
Right: Sodium hydroxide is an extremely dangerous base which can cause terrible burns

  • The reaction of an acid and a base is called neutralisation

  • The cells in the lining of our stomach produce hydrochloric acid

  • Examples if Neutralisation Inlcude:

  • Antacid (meaning against acid) are bases that cure stomach aches by reacting with the excess acid in the stomach

  • Milk of magnesia contains magnesium hydroxide (a base) which also reacts with hydrochloric acid in the stomach

  • If soil is too acidic a substance commonly known as lime (calcium oxide/cao) is spread to neutralise the acid and make the field more fertile

  • Toothpaste is slighlty alkaline to counteract the acids in the food we eat

  • A bee sting is acidic and we use baking soda to neutralise this and ease the pain

  • A wasp sting is basic and we can use vinegar to react with the base

  • The neutralisation of an acid and a base forms salt, water and sodium chloride

  • This salt is formed when the hydrogen in an acid is replaced by a metal

Common Neutralisations:
Left: The spreading of lime to increase fertility is a common example of neutralisation
 
Right: Mil of magnesia is commonly used for "acid reflux" (Excess acid)

  • Sulfuric Acid + Sodium Hydroxide = Sodium Sulfate and water

  • Nitric acid + Sodium Hydroxide = Sodium Nitrate and water

  • There are many different types of salt sodium chloride, sodium sulfate and sodium nitrate

Acid Rain:

  • Water and carbon dioxide combined create a weak carbonic acid

  • Rainwater with a P.H of less than 5.5 is considered to be acid rain

  • Acid rain contains both sulfuric and nitric acids. 

  • The sulfuric acid in acid rain mostly comes from the burning of fossil fuels which contains a little sulfur. When these fossil fuels are burned they release sulfur dioxide which mixes with water to form sulfurous acid

  • This sulfurous acid is then converted into sulfuric acid by oxygen. Oxides of nitrogen comes from the exhaust emmisions of cars. These oxides dissolve in water vapour in the clouds to form nitric acid

  • Therefore acid rain contains some sulfuric and nitric acid which is now corrosive and is damaging to fish in lakes, limestone structures and trees by destroying its foliage

Solutions to acid rain:

  • Remove the sulfur dioxide from fossil fuels before it leaves the chimneys using for example limestone which would react with the sulfur

  • Remove all sulfur content from oil and gas

  • Catyst converters could be installed in car engines to remove oxides of nitrogen

Damaging effects of acid rain
The above diagram explains the formation of acid rain

© 2016 by Vincent Savage and John Harrington. Young Scientists and Historians

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