Which among the following equations represents the first law of thermodynamics under isobaric conditions ?

Question

Which among the following equations represents the first law of thermodynamics under isobaric conditions ? (A) Δ U = qp - Pex . Δ V  (B) qv = Δ U  (C) Δ U = W  (D) W =-q

Tardigrade Admin · Accepted Answer

According to first law of thermodynamics,

Δ U = q + W

In case of isobaric conditions, change of state is brought about at constant pressure, i.e.

d p = Q

Moreover, work done for a process is given as

W = - p_{ext.} Δ V

.

Substituting the value of 'W' in first law of thermodynamics

Δ U = q_{p} - p_{ext} \cdot Δ V

Q. Which among the following equations represents the first law of thermodynamics under isobaric conditions ?

$Δ U = q_{p} - P_{e x} .Δ V$

$q_{v} = Δ U$

$Δ U = W$

$W = - q$

Q. Which among the following equations represents the first law of thermodynamics under isobaric conditions ?

ΔU=qp​−Pex​.ΔV

qv​=ΔU

ΔU=W

W=−q

According to first law of thermodynamics, ΔU=q+W In case of isobaric conditions, change of state is brought about at constant pressure, i.e. dp=Q Moreover, work done for a process is given as W=−pext. ​ΔV. Substituting the value of 'W' in first law of thermodynamics ΔU=qp​−pext ​⋅ΔV

$Δ U = q_{p} - P_{e x} .Δ V$

$q_{v} = Δ U$

$Δ U = W$

$W = - q$