The value of delta at 25c for the formation of pocl3.

°ΔG rxn = -1108.7

Maybe the question is like this

the value of ΔG° at 25 °C for the formation of POCl₃

Reaction

P₂(g)+O₂(g)+3Cl₂(g)⇒2POCl₃(g)

Formula

You can find table to find ΔG° at 25 °C(298 K)

°ΔG POCl₃ = -502.5 kJ/mol

°ΔG O₂ and °ΔG Cl₂ = 0

°ΔG P₂ = 103.7 kJ/mol

1. 1 mole of anything contains 6.022x10^23 pieces  

d  

2. a  

3. c, number  

5. 1.24x10^24atoms / 6.022x10^23atoms/mole = 2moles h2 atoms  

6. fe2br3 mass = 2moles x mass fe + 3 moles x mass br  

molar mass = grams / number of moles = g/mole  

to find moles = g / molar mass  

to find mass = g = molar mass / moles