Question

A system undergoes a change such that the pressure changes from 0.36 atm to 0.34 atm and the volume changes from 8 L to 19 L. Simultaneously. Δυ-358 J. What is ΔΗ in Joules?

Answer 1

Answer : The value of $\Delta H$ is 4.76 J

Explanation :

Formula used :

$\Delta H=\Delta U+\Delta n_g\times RT$

According to the ideal gas equation,

$PV=nRT\\\\\Delta(PV)=\Delta n_gRT$

So,

$\Delta H=\Delta U+\Delta (PV)$

$\Delta H=\Delta U+(P_2V_2-P_1V_1)$

where,

$\Delta U$ = internal energy of the reaction = -358 J

$\Delta H$ = enthalpy of the reaction = ?

$P_1$ = initial pressure = 0.36 atm

$P_2$ = final pressure = 0.34 atm

$V_1$ = initial volume = 8 L

$V_2$ = final volume = 19 L

Now put all the given values in the above formula, we get:

$\Delta H=\Delta U+(P_2V_2-P_1V_1)$

$\Delta H=(-358J)+(0.34\times 19-0.36\times 8)L.atm$

$\Delta H=(-358J)+3.58L.atm$

conversion used : $1L.atm=101.33J$

$\Delta H=(-358J)+3.58\times 101.33J$

$\Delta H=4.76J$

Therefore, the value of $\Delta H$ is 4.76 J