Chemistry Exam Neutralisation Flashcards
Name four indicators
Universal indicator
Phenolphthalein
Litmus paper
Methyl orange
How does litmus paper change in alkaline/acidic conditions?
Blue litmus turns red in acid and stays blue in alkaline
Red litmus stays red in acid and turns blue in alkaline
Describe the colour changes within universal indicator for alkaline, acid and water
In alkaline - from dark green to dark purple
Acid - red to orange
Water - green
Describe the colour changes for phenolphthalein in water, acid and alkaline
Acid - colourless
Water - colourless
Alkaline - pink
Describe the colour changes with screened methyl orange in water, alkaline and acid
Water - orange
Acid - red
Alkaline - yellow/orange
Why is phenolphthalein limited in its use?
Using it for testing acid and water can be confusing because it turns colourless for both products
Why is methyl orange limited in its use?
The results when used in water or alkaline are both similar as orange and orange/yellow
In universal indicator, what colour would turquoise indicate on the pH scale?
9
In universal indicator, what colour would yellow indicate on the pH scale?
3
In universal indicator, what colour would purple indicate on the pH scale?
12/13
Give three examples of neutralisation reactions in real life:
- Wasp stings are alkaline and are neutralised with vinegar
- Decaying food particles produce acid which is neutralised by tooth paste when we brush our teeth
- Baking power contains an acid called bicarbonate of soda which is neutralised by water and this releases carbon dioxide
State the differences between bases and alkaline
Bases are substances that react with acids and neutralises them. They are usually metal oxides, metal hydroxides, metal carbonates or metal hydrogen carbonates. Bases are insoluble in water, therefore if they dissolve in water they are an alkaline base.
