10 mole of an ideal gas is undergoing the cyclic process described below, drawn on a P-V diagram with P in Pa and V in m3 (the volume axis is marked at 1, 2, 3, 4 and 5): the gas is first taken along the constant-volume line V=1m3 from P1 up to P2, then expanded along a falling curve from V=1m3 out to V=5m3, then dropped vertically at V=5m3, and finally compressed along a lower curve back to the starting state (V=1m3, P=P1). The heat involved in the process from P1 to P2 is α Joule (P1=21.7Pa,P2=30Pa,Cv=21J/K⋅mol,R=8.3J/mol⋅K). The value of α is _____.