How much energy is required to decompose 612 g of pcl3, according to the reaction below? the molar mass of pcl3 is 137.32 g/mol and may be useful. 4 pcl3 (g) ? p4 (s) + 6 cl2 (g) ? h°rxn = + 1207 kj

a. 1.85 * 103 kj

b. 3.46 * 103 kj

c. 5.38 * 103 kj

d. 1.34 * 103 kj

e. 4.76 * 103 kj?

The reaction is:

4 PCl3 (g) - - - > P4 (s) + 6 Cl2 (g).

Now, you need to convert the mass of PCl3 into number of moles, for which you use the molar mass of PCl3 in this way:

number of moles = number of grams / molar mass = >

number of moles of PCl3 = 612 g / 137.32 g/mol = 4.4567 moles of PCl3.

Now use the proportion with the ΔH rxn given.

4 mol PCl3 / 1207 kJ = 4.4567 mol / x = > x = 4.4567 mol * 1207 kJ / 4 mol = 1,344.8 kJ = 1.34 * 10^3 kJ.

Answer: 1.34 * 10 ^3 kJ (option d)