Types of Chemical Reactions
Synthesis Reaction
A synthesis reaction is a chemical reaction in which two (or more) substances react to form one product. The following general equation represents a synthesis reaction:
2H2 + O2 → 2H2O
Decomposition Reaction
A decomposition reaction is a chemical reaction in which one substance is broken down into two (or more) simpler substances. The following general equation represents a decomposition reaction:
2HgO → 2Hg + O2
Single Replacement Reaction
A single replacement reaction is a chemical reaction in which one element replaces another element in a compound The following general equation represents a single replacement reaction:
Na + AgCl → NaCl + Ag
Double Replacement Reaction
A double replacement reaction is a chemical reaction which involves the reaction of two compounds to form two new compounds. The following general equation represents a double replacement reaction:
2KF + SrCl2 → SrF2 + 2KCl
Exothermic Reaction
An exothermic reaction is a chemical reaction that releases energy (heat) to the surroundings.
Endothermic Reaction
An endothermic reaction is a chemical reaction that absorbs energy (heat) from the surroundings.
Signs that a Chemical Reaction has Occurred
- Formation of a precipitate (you will see anything from a cloudy solution to full-on chunks)
- Permanent colour change (you will see a change of colour that lasts for at least 20 seconds)
- Formation of a gas (you will see anything from a bubble every several seconds to full-on crazy)
- Release or absorption of energy (you will feel the reaction vessel get colder or hotter)
Question of the Day #15:
What type of reaction is represented by each of the following equations? Also, balance each equation.
(a) Al + Fe2O3 → Al2O3 + Fe
(b) HgO → Hg + O2
(c) Fe + H2SO4 → FeSO4 + H2
(d) KF + NaCl → KCl + NaF
(e) Fe + Cl2 → FeCl3
Homework:
Answers:
