Naphthalene (C10H8)is a solid aromatic compound often sold as mothballs.The complete combustion of this substance to yield CO2(g)and H2O(l)at 25 ْC yields -5154 kJ/mol.

Question

A. write balanced equation for the combustion of C10H8.
C10H8+12O2->10CO2+4H2O ΔH =-5154
B. write a balanced equation for the formation of C10H8 fro the elements and calculate its ΔH o f.
5154= [x+0]-[10(-394)+4(-286)]
5154=[x+0]-[-3940+-1144]
5154=x+5084
x=70

Answer 1

I think you have the correct answer but I'm not sure you arrived at it correctly.
Isn't
dH_rxn= dH_products - dH_reactants.
That will give you 70 kJ/mol for C10H8.
You have worked it as
reactants - products and changed the sign of dH combustion.

Answer 2

Napthalene has the formula C10H8.It burns in air according to the equation
C10H8+12O----->10Co2+4H2O
16g of napthalene was burnt in excess oxygen.
a)Calculate the number of moles of napthalene burnt.
b)Calculate the mass of water produced in the combustion .
c)Calculate the volume of Co2 produced at r.t.p.
d)Clculate the moles of oxygen needed for the reaction.