Types of Chemical Reactions — Chemistry Mnemonic
Target: mnemonic for types of chemical reactions class 10
Why is this hard to memorize?
Class 10's very first chemistry chapter sorts every reaction you'll ever balance into five buckets: combination, decomposition, displacement, double displacement, and oxidation-reduction (redox). Board papers love one-line identification questions ("name the type of reaction" for 1 mark) and also test writing a general equation for each type. The trap is that decomposition looks like the reverse of combination, and displacement is easy to confuse with double displacement — you need a memory hook that keeps the direction of each reaction straight, not just the names.
Classic mnemonics you should know
"Chemists Don't Do Dishes, they React — Combination, Decomposition, Displacement, Double displacement, Redox"
The first letters C-D-D-D-R spell out the five types in the exact order CBSE textbooks introduce them, so you can recite the full list before even looking at the question.
"Combination = marriage (A + B → AB). Decomposition = divorce (AB → A + B). Displacement = affair (A + BC → AC + B, one partner is replaced). Double displacement = partner-swap (AB + CD → AD + CB, both couples swap)."
Turning the reactions into a relationship story makes the arrow direction and the number of products impossible to forget — marriage joins, divorce splits, an affair replaces one partner, a swap replaces both.
"OIL RIG — Oxidation Is Loss (of electrons), Reduction Is Gain (of electrons)"
Every redox reaction question eventually asks which reactant is oxidised and which is reduced. OIL RIG fixes it instantly: losing electrons = oxidation, gaining electrons = reduction.
The complete list
- Combination reaction — A + B → AB (two or more reactants combine into one product)
- Decomposition reaction — AB → A + B (one reactant breaks into two or more products)
- Displacement reaction — A + BC → AC + B (a more reactive element displaces a less reactive one)
- Double displacement reaction — AB + CD → AD + CB (ions exchange partners, often forming a precipitate)
- Oxidation-reduction (redox) reaction — simultaneous oxidation (loss of electrons) and reduction (gain of electrons)
Frequently asked questions
What are the 5 types of chemical reactions in Class 10?
Combination, decomposition, displacement, double displacement, and oxidation-reduction (redox). CBSE also treats exothermic/endothermic as a separate classification that can overlap with any of these five.
What is the easiest way to tell displacement and double displacement apart?
Count how many elements/ions change places. In displacement, only ONE element swaps out (A + BC → AC + B). In double displacement, BOTH parts swap (AB + CD → AD + CB) — think of it as an ionic partner exchange, usually forming a precipitate.
How do I remember oxidation and reduction quickly for exams?
Use OIL RIG: Oxidation Is Loss of electrons, Reduction Is Gain of electrons. If a substance loses electrons (or gains oxygen/loses hydrogen), it's oxidised; if it gains electrons (or loses oxygen/gains hydrogen), it's reduced.
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