The values are given in the table below

substance δh°f (kj/mol)
so2 (g) −297
so3 (g) −396
so2cl2 (g) −364
h2so4 (ℓ) −814
h2o (ℓ) −286

the value of δh° for the following reaction is −62.1 kj. what is the value of δh°f for hcl(g)?

so2cl2(g) + 2 h2o(ℓ)→ h2so4(ℓ) + 2 hcl(g)

ΔH°f,HCl = - 92.05 KJ/mol

Explanation:

∴ ΔH°rxn = 62.1 KJ/mol

⇒ - 62.1 KJ/mol = 2 ΔH°f,HCl(g) + ΔH°f,H2SO4(l) - 2 ΔH°f,H2O(l) - ΔH°f,SO2Cl2(g)

⇒ 2 ΔH°f,HCl = - 62.1 KJ/mol + 2 ΔH°f,H2O(l) + ΔH°f,SO2Cl2(g) - ΔH°f,H2SO4(l)

⇒ 2 ΔH°f,HCl = - 62.1 KJ/mol + 2 (-286 KJ/mol) - 364 KJ/mol - (- 814 KJ/mol)

⇒ 2 ΔH°f,HCl = - 62.1 KJ/mol - 572 KJ/mol - 364 KJ/mol + 814 KJ/mol

⇒ 2 ΔH°Δf,HCl(g) = - 62.1 KJ/mol - 122 KJ/mol

⇒ 2 ΔH°f,HCl(g) = - 184.1 KJ/mol

⇒ ΔH°f,HCl(g) = ( - 184.1 KJ/mol ) / 2 = - 92.05 KJ/mol

the ideal gas law equation is as follows

pv = nrt

where p - pressure

v - volume

n - number of moles

r - universal gas constant

t - temperature

so if the pressure, volume and temperature are already known

we are left with n and r

since r is the universal gas constant that has a known fixed value then r too is known

so we are left with 'n'

once we know temperature volume and pressure

we can find the number of moles of gas present using the ideal gas law equation

this is not my own answer, this is an answer for the same question by the user blahblahmali. i do not claim ownership of this account.

4d^55s^1 ( third choice)