Question

Worksheet 17c (Gen Chem) Other Equilibria 236- The ton cadmium ) is toxic. To remove cadmium(II)ions (255 L. 121 x 10M ) from wastewater (res from mining and metal processing) it is precipitated with hydroxide ions (1.00 L, 6.00 M). What mass of cadmium hydroxide will precipitate? How much cadmium(II) ion is left in the wastewater?

Answer 1

The reaction between Cd²+ ion and of ion is given below - CdL (ag) +20 H (99) = Cd (OH), cd COH) is a sparingly soluble salt its solubilitis Product Ksp = 7.2 x 10-15 [ca2+] [OH-] ² = 7.281015 -21X155m • 004 to 255L waste water contains 1.21x105 m Cd (1) 12 NaOH Solution , strength is 6 (M) ium ion : when IL Nath solution mined with 255L waster watir, Total volume = (255+1) L = 256L. . Strength of Cd2+ ion streng that Nath solution 12 x 6M 255L }-21X105 M = 256L 256L = 0.0234M = 1.205*10-SM Now, in presence of OH-ion, set concentration of Cd (I) is a molln [Ca 2+] [OH-]² = 7.2*1515 xx(0.0234) = 7.2118915 n = 13.15×10 10 molln " 13.15810-10 (M) cd (II) solution of will be result after addition of Naoh solution. I t Solution Contains 13.15 x 101 moles ed(I) 256 01 in (3.15*10-10x256) moles com) - 3.4 x 10- I moles of cd. " Amount of cd I) Precipitate out. =(1205x105_13.15x1070) = 1. 2048105M.