What is the enthalpy of formation of 2C10H22+31O2=20CO2+22H2O

This would be an enthalpy of combustion, not formation. The heat of combustion for decane is 6777.45kJ/mol.

The enthalpy of formation of a compound is the change in enthalpy (heat) that occurs when 1 mole of the compound is formed from its constituent elements in their standard states. To calculate the enthalpy of formation of a compound, you need to know the enthalpy of formation of each element in its standard state and use the balanced chemical equation.

Here's how you can calculate the enthalpy of formation of 2C10H22 + 31O2 = 20CO2 + 22H2O:

1. Find the enthalpy of formation for each compound involved. The enthalpy of formation values can be found in reference books or online databases. The enthalpy of formation is usually given in units of kJ/mol.

For this reaction:
- The enthalpy of formation of CO2 is -393.5 kJ/mol.
- The enthalpy of formation of H2O is -285.8 kJ/mol.

2. Multiply the enthalpy of formation values by the stoichiometric coefficients from the balanced chemical equation.

For CO2: 20 mol * (-393.5 kJ/mol) = -7870 kJ/mol
For H2O: 22 mol * (-285.8 kJ/mol) = -6288 kJ/mol

3. Calculate the sum of the enthalpies of formation of the products.

Enthalpy of formation of products = Enthalpy of formation of CO2 + Enthalpy of formation of H2O
= -7870 kJ/mol + (-6288 kJ/mol) = -14158 kJ/mol

4. Calculate the sum of the enthalpies of formation of the reactants.

Enthalpy of formation of reactants = 2C10H22 + 31O2
= 2 mol * unknown + 31 mol * 0 kJ/mol (since O2 is an element in its standard state)

5. Calculate the difference between the enthalpies of formation of the products and the reactants.

Enthalpy of formation of the reaction = Enthalpy of formation of products - Enthalpy of formation of reactants
= (-14158 kJ/mol) - (2 * unknown kJ/mol) = 0 (assuming the reaction is balanced)

To solve for the unknown value, you need more information about the enthalpy of formation of the reactant 2C10H22.