SSC CGL Chemistry · Acids, Bases and Salts
Acids, Bases and Their Reactions
Acetic acid and vinegar, baking soda in milk and fire extinguishers, what a metal and a dilute acid give, and the order of strength of the alkali hydroxides.
Why this matters
Eight questions in the bank: one from the 2023 shifts and seven from the 2024 shifts, seven of them EASY. Three ask the same reaction (a metal with dilute sulphuric acid), so the one general rule here answers them all.
Concept 1 of 2: Acids and bases at home
Definition
Acids:
- Ethanoic acid is acetic acid; vinegar is a 5 to 8% solution of it, used as a souring agent in pickles and sauces.
Baking soda (sodium bicarbonate, NaHCO3):
- A white crystalline powder that neutralises both acids and bases; used as an antacid.
- It gives off CO2 in soda-acid fire extinguishers.
- A milkman adds a little to milk to raise its pH from about 6 to slightly alkaline, so the milk sours later.
Practise this conceptself-check · 3 quick reps
The same idea in a real exam question:
Example 1 · Acids, Bases and Salts · Acids, Bases and Their Reactions
Alkaline means a higher pH
Concept 2 of 2: Metals with acids, and base strength
Definition
The rule: metal + dilute acid gives salt + hydrogen.
- Zinc + sulphuric acid gives zinc sulphate + hydrogen (it burns with a pop).
- Magnesium + dilute sulphuric acid gives magnesium sulphate + hydrogen. Sulphur dioxide comes only from hot, concentrated acid.
Base strength: down Group 1 the hydroxides grow stronger: CsOH > KOH > NaOH > LiOH.
Practise this conceptself-check · 3 quick reps
The same idea in a real exam question:
Example 2 · Acids, Bases and Salts · Acids, Bases and Their Reactions
Dilute acid gives hydrogen, not SO2
Summary — formulas & gotchas at a glance
A revision cheat-sheet for the formulas and gotchas above. Click any concept name to jump back to its full explanation.
Reference tables (2)
Watch out for (2)
- Alkaline means a higher pH→ Acids and bases at home
- Dilute acid gives hydrogen, not SO2→ Metals with acids, and base strength
Test yourself on a real paper
Sit a past SSC CGL paper, timed and marked the way the exam marks it. You see your score and every answer the moment you finish. Free to start.