89.6 Rate Theories of elementary reaction If reaction takes place whenever the molecules collides AB=TLd2/8RT AB [A][B] k=7.88x104 mol-1dm3.s-1 When Co=1.00 mol dm-3, the half-life of HI is 1.27 x 10-5s. This result differs greatly d(N d (nal dJA from the experimental fact ddt ddt Only the molecules posses energy excess to dAI AB aRT a critical value (E] can lead to reactive LAB dt LId l ollision 8RT k[AJB]k=dIf reaction takes place whenever the molecules collides: 2 2 AB AB 8 [A][B] RT Z L d   = ( A A ) ( ) AB d d [A] d d d d N n L d Z L V t V t dt = − = − = −  AB 2 AB [A] 8 [A][B] d RT Z r d L dt L   = − = = r k = [A][B] 2 AB 8RT k d L   = k = 7.88 104 mol-1 dm3 s -1 When c0 = 1.00 mol dm-3 , the half-life of HI is 1.27  10-5 s. This result differs greatly from the experimental fact. §9.6 Rate Theories of elementary reaction Only the molecules posses energy excess to a critical value (Ec ) can lead to reactive collision