White phosphorus (P4) was used for a long time in military incendiary bombs and ordnances. White phosphorus reacts with oxygen in the air and burns at very high temperatures, so it sets things on fire. Calculate the change in enthalpy resulting from a 25.0 pound white phosphorus artillery shell reacting with the oxygen in the atmosphere to form P4O10 (s). The enthalpy of formation can be found in an appendix of your text book. Give the answer in MJ (mega-joules).

Works the same way as dG but this is dH.

Write ad balance the equation.
dHrxn = (n*dHo products) - (n*dHo reactants). Of course you will need ton convert 25 lbs to grams.

To calculate the change in enthalpy resulting from the reaction of white phosphorus (P4) with oxygen to form P4O10, we need to use the enthalpy of formation values.

The reaction can be represented as follows:

4P + 5O2 -> P4O10

We need to find the enthalpy of formation (ΔHf) values for P4 and P4O10.

1. Look up the value for the enthalpy of formation of P4 from the appendix of your textbook. Let's assume it is -263.2 kJ/mol.

2. Look up the value for the enthalpy of formation of P4O10 from the appendix of your textbook. Let's assume it is -2943.8 kJ/mol.

3. Calculate the number of moles of white phosphorus (P4) in the 25.0 pound artillery shell. We need to convert the mass of the shell to moles using the molar mass of P4.

The molar mass of P4 is 4 * (atomic mass of P) = 4 * 30.974 g/mol = 123.896 g/mol.

25.0 pounds = 25.0 * 0.453592 kg = 11.3398 kg.
Convert to grams: 11.3398 kg * 1000 g/kg = 11339.8 g.
Convert to moles: 11339.8 g / 123.896 g/mol = 91.4402 mol.

4. Calculate the change in enthalpy (ΔH) for the reaction using the formula:

ΔH = (ΔHf of P4O10 - ΔHf of P4) * number of moles.

ΔH = (-2943.8 kJ/mol - (-263.2 kJ/mol)) * 91.4402 mol.

5. Convert the result to mega-joules (MJ). There are 1000 kJ in 1 MJ.

ΔH = (△H) / 1000 = (result) kJ = (result) MJ.

Follow these steps to find the values in your textbook appendix and perform the necessary calculations to obtain the change in enthalpy in mega-joules (MJ).