Chemical Reactions: Prediction of Products
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1.Synthesis reaction: occurs when two or more simple substances (elements or compounds) are combined to form one new and more complex substance. The general form of a synthesis reaction is

element or compound + element or compound --> compound

Fe + S --> FeS
2.Single displacement reaction: occurs when one element displaces another in a compound. The general form of a single displacement reaction is

element + compound --> element + compound

Zn + 2HCl --> H2 + ZnCl2
3.Double displacement reaction: occurs when the cation (+) and the anion (-) of the two reactants are interchanged. The general form of a double displacement reaction is

compound (AB) + compound (CD) --> compound (AD) + compound (CB)

FeS +2HCl --> FeCl2 + H2S
4.Decomposition reaction: occurs when energy in the form of heat, light, electricity, or mechanical shock is supplied. A compound may decompose to form simpler compounds and/or elements. The general form of a decomposition reaction is

compound --> two or more substances

There are six general types of decomposition reactions

a.Some oxy-acids, when heated, decompose to form water and the nonmetal oxide.

H2CO3 --> H2O + CO2
b.Some metallic hydroxides, when heated, decompose to form the metal oxide and water.

Ca(OH)2 --> CaO + H2O
c.Some metallic carbonates, when heated, decompose to form the metal oxide and carbon dioxide.

Li2CO3 --> Li2O + CO2
d.Some metallic chlorates, when heated, decompose to form metal chloride and oxygen gas.

2KClO3 --> 2KCl + 3O2
e.Most metallic oxides are stable, but a few decompose when heated to form the metal and oxygen gas.

2HgO --> 2Hg +O2
f.Some compounds can be decomposed by electricity into their elements.

2NaCl --> 2Na + Cl2

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This page was made by Erik Epp.