Writing and balancing chemical equations is a basic skill for chemistry students. They must learn to predict the chemical products of the reaction when only the chemical reactants are given.
Types of Chemical Reactions
Synthesis reactions
Two or more reactants combine to form a new chemical product.
Examples:
C(s) + O2(g) → CO2(g)
H2O(l) + SO3(g) → H2SO4(aq)
Decomposition reactions
One reactant decomposes into two or more chemical products.
Examples:
H2CO3(aq) → H2O(l) + CO2(g)
CaCO3(s) → CaO(s) + CO2(g)
Single-replacement reactions
A single element replaces a similar element in adjacent reactants.
Examples:
Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s)
Double-replacement reactions
Two ionic compounds exchange ions to produce two new ionic compounds.
Examples:
NaCl(aq) AgNO3(aq) → NaNO3(aq) + AgCl(s)
HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l)
Combustion reactions
A single element or compound combines with oxygen that releases energy. This rapid oxidation is called combustion.
Examples:
C(s) + O2(g) → CO2(g) + energy
2Mg(s) + O2(g) → 2MgO(s) + energy
