Acids and alkalis: pH scale, strong and weak acids

Acids and alkalis

• Acids and alkalis
• Strong acids
• sulphuric acid (accumulator acid, found in car batteries)
• hydrochloric acid (in our stomach to kill germs)
• nitric acid (used in the manufacture of explosives and fertilizers)
• NOTE: strong acids are a lot more dangerous than weak acids.
• Acids are CORROSIVE which means they will attack and weaken many things including metals, paper, clothing and skin.
• A concentrated acid or alkali is more dangerous than a dilute one.
• To make something more dilute water needs to be added.
• CONCENTRATED means without much or without any water added.
• DILUTE means a lot of water added.
• ALKALIS ( alkaline solutions) Alkalis have the following properties:
• Have a pH value more than pH 7
• Turn red litmus indicator blue
• Can neutralise an acid
• Feel soapy to touch (reacts with fat to form soap)
• Examples of common alkalis:
• caustic soda (sodium hydroxide): used to clean ovens and drains
• washing soda (sodium carbonate)
• ammonia solution (often used in household cleaners)
• garden lime (calcium oxide): used to neutralise acid in the soil
• indigestion powder (often magnesium hydroxide)
• Alkalis are caustic which means they will burn skin and eyes.
• A strong alkali (like caustic soda) is VERY dangerous.
• NEUTRAL LIQUIDS
• A neutral liquid is one with a pH value equal to pH 7.
• examples: water, salt (sodium chloride) solution, sugar solution
• THE pH SCALE
• A scale of numbers ranging from 1 to 14
• neutral = pH7
• acid = less than pH 7
• alkali = more than pH7

Weak acids

• Weak acids
• Weak acids are the weaker type of acid that has a "weak " reaction in the solution
• citric acid (found in lemons and other citrus fruits) tannic acid (found in tea)acetic (ethanoic) acid (found in vinegar) formic acid (found in ant stings)

Strong acids

• Strong acids
• sulphuric acid (accumulator acid, found in car batteries)
• hydrochloric acid (in our stomach to kill germs)
• nitric acid (used in the manufacture of explosives and fertilizers)
• NOTE: strong acids are a lot more dangerous than weak acids.
• Acids are CORROSIVE which means they will attack and weaken many things including metals, paper, clothing and skin.
• A concentrated acid or alkali is more dangerous than a dilute one.
• To make something more dilute water needs to be added.
• CONCENTRATED means without much or without any water added.
• DILUTE means a lot of water added.

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