At the first reaction when 2HBr(g) ⇄ H2(g) + Br2(g) So Kc = [H2] [Br2] / [HBr]^2 7.04X10^-2 = [H2][Br] / [HBr]^2
at the second reaction when 1/2 H2(g) + 1/2 Br2 (g) ⇄ HBr Its Kc value will = [HBr] / [H2]^1/2*[Br2]^1/2 we will make the first formula of Kc upside down: 1/7.04X10^-2 = [HBr]^2/[H2][Br2] and by taking the square root: ∴ √(1/7.04X10^-2)= [HBr] / [H2]^1/2*[Br]^1/2 ∴ Kc for the second reaction = √(1/7.04X10^-2) = 3.769
They have the same number of electrons in their outer shells. Elements in the same group often share similar chemical properties because the outer electrons generally determine a lot of their properties
