Question

calculate the work done when 50g of iron reats wirh hydrochloric acid in
(a) a closed vessel of fixed volume
(b) an open Beaker at 25'c
​

Answer 1

Answer:

 For  a) 0 J

         b) - 2477.57 J

Explanation:

•   a) Vessel is of fixed volume,

                  Hence ΔV=0.

                  No work is done.

•    b) The gas driver back the atmosphere hence,

                              W=−PexΔV

                Also,  ΔV = V final − V initial = V final  (∴V initial=0)

                   ∴ ΔV = nRTPext   or  W= −Pext = − nRT

where n is the number of mole of H2gas obtained from n mole of Fe(s).

                 Fe(s)+2HCI(aq) → FeCI2(aq)+H2(g)

                          ∴n = 56/56 = 1mol

                          ∴w = −1×8.314×298 = −2477.57J

The reaction mixture in the given system does 2.477kJ of work driving back to atmosphere.