There are five common types of chemical reactions:1. Synthesis combination reaction: Two or more substances combine to form a single product. The general form is A + B AB.Example: 2H2 g + O2 g 2H2O l 2. Decomposition reaction: A single compound breaks down into two or more simpler substances. The general form is AB A + B.Example: 2H2O l 2H2 g + O2 g 3. Single displacement replacement reaction: One element replaces another element in a compound. The general form is A + BC AC + B.Example: Zn s + 2HCl aq ZnCl2 aq + H2 g 4. Double displacement metathesis reaction: Two compounds exchange ions to form two new compounds. The general form is AB + CD AD + CB.Example: AgNO3 aq + NaCl aq AgCl s + NaNO3 aq 5. Combustion reaction: A substance reacts with oxygen, usually producing heat and light, to form one or more oxides. The general form for hydrocarbon combustion is CxHy + O2 CO2 + H2O.Example: CH4 g + 2O2 g CO2 g + 2H2O g To balance chemical equations, follow these steps:1. Write the unbalanced equation with correct chemical formulas for reactants and products.2. Count the number of atoms of each element on both sides of the equation.3. Balance the elements one at a time by adjusting the coefficients the numbers in front of the chemical formulas . Start with the most complex substance or the element that appears in the greatest number of compounds.4. Check that the number of atoms of each element is the same on both sides of the equation.5. Make sure the coefficients are in the lowest whole number ratio.Example: Balancing the combustion of propane C3H8 :Unbalanced equation: C3H8 + O2 CO2 + H2O1. Balance carbon atoms: C3H8 + O2 3CO2 + H2O2. Balance hydrogen atoms: C3H8 + O2 3CO2 + 4H2O3. Balance oxygen atoms: C3H8 + 5O2 3CO2 + 4H2OThe balanced equation is: C3H8 + 5O2 3CO2 + 4H2O