Consider the gold-platinum system which has a value of delta w of -4250 J/mole;

Question

(a) Calculate the enthalpy of mixing for a solution of 10% platinum and 90% gold. Express your answer in units of kJ/mole.

(b) Is the dissolution of 10% platinum into gold an endothermic or an exothermic process?
i)Exothermic as the change in enthalpy is negative.
ii)Endothermic as the change in enthalpy is positive.
iii)Impossible to tell without considering the entropy of the system.

Answer 1

b) i

Answer 2

Any idea on (a)?

Answer 3

-2.295

Answer 4

The formula and explanation are given in the lecture video S23V2, in this case what you need to be cautious is the Z, Pt and Au are FCC structure, hence you need to draw the unit cell and its surrounding unit cell to get the idea of the coordination number.