b. The decomposition reaction may be written in this form:

C12O36H20N12 (s) → 12CO2 (g) + O2 (g) + 6N2 (g) + 10H2O (l)
In the enthalpy diagram below, the arrows represent standard enthalpy reactions. (3) denotes the standard enthalpy of decomposition of C12O36H20N12 (s). Provide an appropriate label for the arrows (1), (2) and (4).

(3) C12O36H20N12 (s) --> 12CO2 (g) + O2 (g) + 6N2 (g) + 10H2O(l)

(1) 12C (s) + 18O2 (g) + 6N2 (g) + 10H2 (g) --> 12CO2 (g) + 6O2 (g) + 6N2 (g) + 10H2 (g)

(2) 12CO2 (g) + 6O2 (g) + 6N2 (g) + 10H2 (g) --> 12CO2 (g) + O2 (g) + 6N2 (g) + 10H2O(l)

(4) 12C (s) + 18O2 (g) + 6N2 (g) + 10H2 (g) --> C12O36H20N12 (s)

To label the arrows correctly in the enthalpy diagram, we need to identify the reactants and products involved in each reaction represented by the arrows.

(1) The reactant in this reaction is 12C (s) + 18O2 (g) + 6N2 (g) + 10H2 (g), and the products are 12CO2 (g) + 6O2 (g) + 6N2 (g) + 10H2 (g). Therefore, the appropriate label for arrow (1) is the combustion of carbon and hydrogen to form carbon dioxide, nitrogen, and water.

(2) The reactants in this reaction are 12CO2 (g) + 6O2 (g) + 6N2 (g) + 10H2 (g), and the products are 12CO2 (g) + O2 (g) + 6N2 (g) + 10H2O (l). This reaction involves the conversion of excess oxygen to water. Therefore, the appropriate label for arrow (2) is the conversion of excess oxygen to water.

(4) The reactant in this reaction is 12C (s) + 18O2 (g) + 6N2 (g) + 10H2 (g), and the product is C12O36H20N12 (s). This reaction represents the formation of the complex compound C12O36H20N12 (s). Therefore, the appropriate label for arrow (4) is the formation of C12O36H20N12 (s).

Keep in mind that these labels are specific to the reactions represented by each arrow and may vary depending on the context of the problem.