Consider the conversion of white tin to gray tin: Sn(white)→ Sn(gray)ΔH° = -2.09 kJ ΔS° = -7.41 J/K
Based on these data,

Question

Quizplus · Accepted Answer

The stability of the phases can be determined by calculating the temperature at which the free energy change (ΔG) for the conversion is zero. Using the equation ΔG = ΔH - TΔS, and setting ΔG to zero for equilibrium, we solve for T (temperature in Kelvin). The conversion from J to kJ for ΔS is necessary, making ΔS = -0.00741 kJ/K. Solving for T gives T = ΔH/ΔS = -2.09 kJ / -0.00741 kJ/K ≈ 282 K. Converting 282 K to Celsius gives approximately 9°C. Since ΔH is negative and ΔS is negative, the reaction is spontaneous (favorable) at temperatures below the calculated temperature, meaning gray tin is stable below 9°C and white tin is stable above 9°C.

Consider the Conversion of White Tin to Gray Tin: Sn(white)→