Two allotropes of tin occur near room temp. The first form of tin is gray tin and is stable at temp. below 13.2 Celsius. Gray tin turns to white tin at temp. above 13.2 Celsius. Densities of gray and white tin are 5.75 g/cm^3 and 7.31 g/cm^3, respectively. Molar heat of the white to gray transition is (delta)H_tr = -2.1 kJ/mol. Heat capacities of the two phases are cp (white) : 26.4 J/mol K and cp (gray) : 25.8 J/mol K Calculate the pressure which must be applied to tin in order to decrease its white to gray transition temperature by 10 Celsius.