chemistry question help

[QatarOwnz]

Hi, Someone help me with this question, I don't get it, why is the answer B?

Which equation represents the reaction for which the enthalpy change, DeltaH, is the
mean bond energy of the C-F bond?
A CF4(g) ------>C(g) + 4F(g)
B ¼CF4(g) ---------> ¼C(g) + F(g)
C C(g) + 4F(g) ------> CF4(g)
D ¼C(g) + F(g) --------> ¼CF4(g)

 

[Mr.Physics]

zahra azam any ideas??

 

[Mr.Physics]

Hi, Someone help me with this question, I don't get it, why is the answer B?

Which equation represents the reaction for which the enthalpy change, DeltaH, is the
mean bond energy of the C-F bond?
A CF4(g) ------>C(g) + 4F(g)
B ¼CF4(g) ---------> ¼C(g) + F(g)
C C(g) + 4F(g) ------> CF4(g)
D ¼C(g) + F(g) --------> ¼CF4(g)

Can you provide the value for enthalpy change of atomistaion of CF4 ?

 

[QatarOwnz]

Can you provide the value for enthalpy change of atomistaion of CF4 ?

Idk, it was not mentioned in the question
this question is from june 2013 unit 1

 

[QatarOwnz]

 

[Mr.Physics]

Hi, Someone help me with this question, I don't get it, why is the answer B?

Which equation represents the reaction for which the enthalpy change, DeltaH, is the
mean bond energy of the C-F bond?
A CF4(g) ------>C(g) + 4F(g)
B ¼CF4(g) ---------> ¼C(g) + F(g)
C C(g) + 4F(g) ------> CF4(g)
D ¼C(g) + F(g) --------> ¼CF4(g)

Answer is B because the mean bond enthalpy of a C-F bond is about 467 kJ mol^-1.
CF4 has 4(C-F) bonds so its mean bond enthalpy is 4(467) kJ mol^-1
1/4(CF4) has mean bond enthalpy of 1/4 ( 4 (467)) which is equal to 467 kJ mol^-1
This is the reason. Hope you get it

 

[zahra azam]

Yeah i get it now too