Question

You mix 25 mL of 1.45 × 10^–4 M silver nitrate with 55 mL of 6.11 × 10–4 M sodium bromide. No precipitation occurs. The Ksp of AgBr is 7.9 × 10^–15. Is the solution unsaturated, saturated, or super saturated

Answer 1

The solution is :

25 ml of 1.458 104 M AgNO3 is mixed with some of 6.11810-4 M NaBr Solution. So, Total Volume after mixing 2 (55+25) = 80 ml -3 No. of millimales of AgNog & M X V (me) = (25x1.45x164) = 0.0036 millimales = 0.0036 8 10-3 moles Concentration of Ag Noz in the final mixture = (0.0036 X 10 3 - 4.5x105 m 80 x 10-3 No. of millimales of Nabe a Mxv (ml) z (6.11X664 x 55) 20.0336 millimales = 0.0336x103 moles Concentration of Naber in the final Mixture a (0.0336x10 3 1 -4 -4.2x10 M 80 x 10-3 Now, the for - equillibrium Ag Br - Ag + + Bu Tonic Product of Ag Br solution will be

Kionic - [Ag+] [Br] = (4.58 10 5) (4.28104 = 1.89 x 108 And the kiss given for Ag ber = 7.981515 So kionic > kep As, the (kionic Ksp) so precipitation should occur. But, in the question it is given that No precipitation occurs. Even having the concentration required for precipitation , precipitation is not taking place i.e. it must be an Oversaturated Solution.