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chemistry igcse acapprinted 90 · PDF 90
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Na + HCl —-> NaCl + H2
Mg + 2HNO3 —-> Mg (NO3)2 + H2
Acids and Bases :
Acid + Base —> Salt + Water
Metal Oxides and Hydroxides can act as bases
The Reaction between an acid and a base is called a neutralization reaction
Example :
MgO + H2SO4 —--> MgSO4 + H2O
Acids can also react with metal carbonates to form a salt , carbon dioxide and water
Indicators
Indicators are substances that change color when added to acidic or basic solutions, helping to
determine the pH of a substance by showing whether it is acidic, basic, or neutral. Here’s a
breakdown of commonly included indicators for IGCSE Chemistry and their color changes in
different solutions:
Litmus
Acid: Red
Neutral: Purple
Base: Blue
Methyl Orange
Acid: Red
Neutral: Yellow-Orange
Base: Yellow
Thymolphthalein
Acid: Colorless
Neutral: Colorless
Base: blue
Universal Indicator (covers a broad pH range and shows a gradient of colors)
Acid: Red to Yellow (pH 0-6)
Neutral: Green (pH 7)
Base: Blue to Purple (pH 8-14)