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Showing 2 questions in Chemistry for Class 10. Tap a card to reveal the answer.
ChemistryAcids, Bases and SaltseasyWhat is the pH scale, and how does pH change as a solution becomes more acidic?
Reveal answer ↓
What it is
pH measures how acidic or basic a solution is, from 0 (acid) to 14 (base), with 7 neutral.
Answer
The pH scale runs from 0 to 14 and measures the concentration of hydrogen ions (H+) in a solution. A pH of 7 is neutral, below 7 is acidic and above 7 is basic. As a solution becomes more acidic, the H+ concentration increases and the pH value decreases.
pH measures H+ concentration (lower pH = more acidic)
- •Scale 0 to 14
- •pH 7 neutral, <7 acidic, >7 basic
- •More acidic -> more H+ -> lower pH
Why learn this
It rules our blood, soil, shampoos, digestion and even why tooth decay happens.
💡 Memory trick
pH goes DOWN as acidity goes UP (more H+ = lower pH). pH = 'power of Hydrogen'.
ChemistryAcids, Bases and SaltseasyWhat is a neutralisation reaction? Give the general equation and one everyday use.
Reveal answer ↓
What it is
A neutralisation reaction is an acid reacting with a base to give a salt and water.
Answer
A neutralisation reaction is the reaction between an acid and a base to form a salt and water. The general equation is: Acid + Base -> Salt + Water (for example, HCl + NaOH -> NaCl + H2O). An everyday use is taking an antacid (a mild base) to neutralise excess acid in the stomach and relieve acidity.
Acid + Base -> Salt + Water
- •Acid + Base -> Salt + Water
- •HCl + NaOH -> NaCl + H2O
- •Use: antacids relieve stomach acidity
Why learn this
It's used in antacids for acidity, in treating soil pH and in soothing insect stings.
💡 Memory trick
Acid + Base -> Salt + Water. The acid and base cancel (neutralise) each other.