Question

All of the questions pertain to the following reaction: 3 Anorthite = Grossular + 2 Kyanite + Quartz 3 CaAl,Si2O3 = Ca3Al2Si3012 + 2 Al2SiOs + SIO2 Thermodynamic data: Anorthite: Hº = -4229.10 kJ/mole S (1 bar, 298K) = 199.3 J/mole-K V (1 bar, 298K)=100.79 cm/mole Grossular: Hº = -6643.14 kJ/mole S (1 bar, 298K) = 255.5 J/mole-K V (1 bar, 298K)=125.3 cm3/mole Kyanite: HP = -2591.73 kJ/mole S (1 bar, 298K) = 83.76 J/mole-K V (1 bar, 298K) = 44.090 cm3/mole Quartz: HP = -910.70 kJ/mole S (1 bar, 298K) = 41.46 J/mole-K V (1 bar, 298K) = 22.688 cm3/mole

1. What is the change in volume for this reaction (ΔVR(1 bar, 298K)) at 298K and 1 bar? Are the products or reactants denser?

2. What is the change in enthalpy for this reaction (ΔHR(1 bar, 298K)) at 298K and 1 bar? Is the reaction exothermic or endothermic?

3. What is the change in internal energy for this reaction (ΔER(1 bar, 298K)) at 298K and 1 bar? For this reaction, under these conditions is q or w the more significant term?

4. What is the change in entropy for this reaction (ΔSR(1 bar, 298K)) at 298K and 1 bar? Are the products or reactants more disordered?

5. What is the change in Gibbs Free Energy for this reaction (ΔGR(1bar,298K)) at 298K and 1 bar? Are the products or reactants stable under these conditions?

Thank you for the help!

Answer 1

The given reaction is - 3 C Al 2 Size = laz Alz Siz 0,2 + 2 Alesi Ost SiO₂ solic eana » The change in volume for this reaction - Av= Total volume of Products - Total volume of ventana - {12513 + (2x 44.090) + 220688}-{ 100.79} cma = {236.168 - 100.79} ama = 135.378 am 3. A As the volume increases, from reactant to product So density decreases. There fore the reactant is more den ser than product. & The change in enthalpy for this reaction - 8pH = Total enthalpy of product – Total enthalky ot, reactant - 3-6649.19+ (2x – 2591,73) +(-910.70)] -{- 4229.10} kJ = (-12737.30 + 4229.10) KT. = – 8508.2 KJ. in Change in enthaltly = – 8568.2 kJ. As the heat evolved during the reaction (duto the negetive sign of 4rH), so the reaction in enothermic.

As all the reactants and the Products are solid, so, the change in internal energy will be equal to change in enthalpy. ise, otro = 4 Hm I u Sens - 8508.2kJ. -reactants, - cm3 As there the fore reaction the contains no. gaseous species. effect of g and w is negligible. luch & The change in entropy, be is given by - 8Sp- Total entropy of Products - total entropy of reactants. . Sæ55.5+ (2x 8376)+ 41.46}-{ 19913} JK-' - (464.98 – 199.3 )JK! = 265.18 J KN The products are more dis ordered. as the entropy increases for the reaction, ut KJ ③ we know, bo Hr - Top :82y ={-8508.2x10%;}-{298 KX265/ JK-1} - - 8508200 J - 79023,645 -65oz = – 8587223.64 J - – 85 87.2236465 Az or=tove so product are stable