Synthesis Reaction
A synthesis reaction is a chemical reaction in which two (or more) substances react to form one product. The following equation represents a synthesis reaction:
2H2 + O2 → 2H2O
Check out this video for an example of a synthesis reaction.
Decomposition Reaction
A decomposition reaction is a chemical reaction in which one substance is broken down into two (or more) simpler substances. The following equation represents a decomposition reaction:
2HgO → 2Hg + O2
Check out this video for an example of a decomposition reaction.
Single Replacement Reaction
A single replacement reaction is a chemical reaction in which one element replaces another element in a compound The following equation represents a single replacement reaction:
Na + AgCl → NaCl + Ag
Check out this video for an example of a single replacement reaction.
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 equation represents a double replacement reaction:
2KF + Sr(ClO3)2 → SrF2 + 2KClO3
Check out this video for an example of a double replacement reaction.
Exothermic Reaction
An exothermic reaction is a chemical reaction that releases energy (heat) to the surroundings.
Check out this video for an example of an exothermic reaction.
Endothermic Reaction
An endothermic reaction is a chemical reaction that absorbs energy (heat) from the surroundings.
Check out this video for an example of an endothermic reaction.
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)
State Symbols
We should use state symbols whenever
possible when writing out chemical formulae.
solid → H2O(s), C(s)
liquid → H2O(l), Br2(l)
gas → H2O(g), CO2(g)
solution → NaCl(aq), NaOH(aq)
Just for fun, check out this video about five of the world's most dangerous chemicals.
Homework:
Follow the instructions for this page, but only do the balancing part for this one if you need extra practice. Also, don't do # 16, 21, 23, 26, 28 - we will talk about wacky reactions like these in the future.
Answers:
