At 27^ C , the degree of dissociation of weak acid (HA) in its 0.5 M aqueous solution is 1 % . Its K _ a value is approximately

Step-by-step solution

degree of dissociation of weak acid (HA) =1 % =1 % 1 100 =0.01 Dissociation constant ( K _ a )= C ^2 where, C( concentration )=0.5 M aligned & ( degree of dissociation )=0.01 & ~K _ a =0.5 (0.01)^2 aligned aligned & =5 10⁻¹ (10⁻² )^2 & =5 10⁻¹ 10⁻⁴ & ~K _ a =5 10⁻⁵ aligned