Question

Calculate the work done (in joules) when 58.3 g of tin dissolves in excess acid at

1.07 atm

and

28

°

C.

Assume ideal gas behavior.

Sn(s) + 2H+(aq) → Sn2+(aq) + H2(g)

Answer 1

Solution:

For the reaction:

Sn + 2H+ = Sn2+ + H2

Step1) Calculation of number of moles of Sn:

Number of moles(n) = mass / molar mass

= 58.3g/118.71 gmol-1 = 0.491 mol

Step 2) Calculation of Volume:

From ideal gas equation, PV =nRT

P = 1.07 atm, R =0.0821 L.atm /mol K, T = 28 +273 =301 K

Then, V = n RT / P

V= 0.491mol x 0.0821 L atm mol-1 K-1 x 301 K / 1.07 atm

V = 11.34 L

Step 3): Calculation of work done:

W = - PV = -1.07 atm x 11.34 L

W = -1.07 x 101325 N m-2 x 11.34 x10^-3 m3

W = -1229.46 J