Question

When 6.0 g of O₂ reacts with CIF as per \[\ce{2ClF_{(g)} + O2_{(g)} -> Cl2O_{(g)} + OF2_{(g)}}\] the enthalpy change is 38.55 kJ. The standard enthalpy of the reaction is ____________.

Options

• 103 kJ

• 456 kJ

• 231 kJ

• 205.6 kJ

Answer 1

When 6.0 g of O₂ reacts with CIF as per \[\ce{2ClF_{(g)} + O2_{(g)} -> Cl2O_{(g)} + OF2_{(g)}}\] the enthalpy change is 38.55 kJ. The standard enthalpy of the reaction is 205.6 kJ.

Explanation:

Number of moles of O₂ = `("Mass of O"_2)/("Molar mass of O"_2)`

= `(6  "g")/(32  "g mol"^-1)`

= 0.1875 mol

The enthalpy change when 0.1875 mol of O₂ react with ClF is 38.55 kJ.

∴ Enthalpy change for 1 mole O₂ = `38.55/0.1875`

= 205.6 kJ

From the reaction, 2 moles of ClF react with 1 mole of O₂.

So, the standard enthalpy of reaction is 205.6 kJ.