Reaction of gaseous fluorine ( F 2) with compound X yields a single product Y, whose mass percent composition is 61.7 % F and 38.3 % Cl. Calculate Δr H° (in kJ / mol ) for the synthesis of Y using following information. 2 ClF ( g )+ O 2( g ) longrightarrow Cl 2 O ( g )+ OF 2( g ) Δ H °=205.6 kJ 2 ClF 3( g )+2 O 2( g ) longrightarrow Cl 2 O ( g )+3 OF 2( g ) Δ H °=533.0 kJ Δ f H °( OF 2, g )=24.7 kJ / mol

Question

Reaction of gaseous fluorine ( F 2) with compound X yields a single product Y, whose mass percent composition is 61.7 % F and 38.3 % Cl. Calculate Δr H° (in kJ / mol ) for the synthesis of Y using following information. 2 ClF ( g )+ O 2( g ) longrightarrow Cl 2 O ( g )+ OF 2( g ) Δ H °=205.6 kJ 2 ClF 3( g )+2 O 2( g ) longrightarrow Cl 2 O ( g )+3 OF 2( g ) Δ H °=533.0 kJ Δ f H °( OF 2, g )=24.7 kJ / mol (A)  (B)  (C)  (D)

Tardigrade Admin · Accepted Answer

Cl :- no. of moles (38.7/35.5)=1.09 F:- (61.7/19)=3.42 Simplest relative ratio 1: 3 So, product Y is ClF 3 compound X is ClF For the synthesis of Y reaction is F 2( g )+ ClF ( g ) longrightarrow ClF 3( g ) 1 / 2 Cl 2 O ( g )+3 / 2 OF 2( g ) longrightarrow ClF 3( g )+ O 2( g ) Δ H °=-533.0 / 2 kJ ⇒-266.5 kJ C / F ( g )+1 / 2 O 2( g ) longrightarrow 1 / 2 Cl 2 O ( g )+1 / 2 OF 2 Δ H °=205.6 / 2 kJ ⇒ 102.8 kJ ( F 2( g )+(1/2) O 2( g ) longrightarrow F 2 O ( g ) Δ H °=24.7 kJ / C / F ( g )+ F 2( g ) longrightarrow C / F 3( g ) ⋅ Δ f H °=-139 kJ / mol )