For the combustion reaction at 298 K 2 Ag (s)+(1/2) O 2( g ) arrow 2 Ag 2 O ( s ) Which of the following alternatives is correct?

Question

For the combustion reaction at 298 K 2 Ag (s)+(1/2) O 2( g ) arrow 2 Ag 2 O ( s ) Which of the following alternatives is correct? (A) Δ H =Δ U (B) Δ H >Δ U (C) Δ H <Δ U (D) Δ H and Δ U has no relation with each other

Tardigrade Admin · Accepted Answer

Δ H =Δ U +Δ nRT Δ n=nP-nR Now, Δ n=2-(5/2)=-(1/2) ∴ Δ H=Δ U-(1/2) R T Thus, Δ U=Δ H+(1/2) R T ∴ Δ U>Δ H

Q. For the combustion reaction at $298 K$
$2 A g (s) + \frac{1}{2} O_{2} (g) \to 2 A g_{2} O (s)$
Which of the following alternatives is correct?

$Δ H = Δ U$

$Δ H > Δ U$

$Δ H < Δ U$

$Δ H$ and $Δ U$ has no relation with each other

$Δ H = Δ U + Δ n RT$
$Δ n = n_{P} - n_{R}$
Now, $Δ n = 2 - \frac{5}{2} = - \frac{1}{2}$
$∴ Δ H = Δ U - \frac{1}{2} RT$
Thus, $Δ U = Δ H + \frac{1}{2} RT$
$∴ Δ U > Δ H$

Q. For the combustion reaction at 298K 2Ag(s)+21​O2​(g)→2Ag2​O(s) Which of the following alternatives is correct?

ΔH=ΔU

ΔH>ΔU

ΔH<ΔU

ΔH and ΔU has no relation with each other