A catalyst slab of half thickness L is used to conduct the first order eaction At 450K the Thiele modulus for the system is 05 The activation energy for the first order rate constant in 100k.l/mol The effective diffusivity of reactant is the slab can be assumed to be independent of temperature and external mass transfer resistance can be neglected if the temperature of the reaction is increased to 470K, calculate the effectiveness factor at 470K