Molar absorptivity data for the cobalt and nickel complexes with 2,3-quinoxalinedithiol are εCo = 36400 and εNi = 5520 at 510 nm and εCo = 1240 and ε Ni = 17500 at 656 nm. A 0.361-g sample was dissolved and diluted to 150.0 mL. A 25.0-mL aliquot was treated to eliminate interferences; after addition of 2,3-quinoxalinedithiol, the volume was adjusted to 50.0 mL. This solution had an absorbance of 1.037 at 510 nm and 0.422 at 656 nm in a 1.00-cm cell. Calculate the concentration of cobalt (in ppm) in the initial solution prepared by dissolving the sample.

What peakes should see in IR spectrum  of the complexes a,b,c,d . a) trans-Ru(II)Cl2(py)4  b) trans-Ru(II)Cl2(acpy)4  c) trans-Ru(II)(NCS)2(py)4  d) trans-Ru(II)(NCO)2(py)4

Scott test is one of the methods used for screening for Cocaine in Forensic Chemistry. The multi step method consists of a) reacting the sample drug with cobaltous thiocyanate b) dissolving of the formed precipitate by adding HCl  and c) extraction of coordination compound with Chloroform d) measurement  of  absorbance of extracted coordination compound at 627 nm What reaction occurs when HCl is added to dissolve the precipitate ? a.Lewis acid- Lewis base reaction b.Lewis acid- Bronsted Lowry base reactionc.Bronsted Lowry acid – Bronsted Lowry base reaction d.Arrhenius acid – Arrhenius base reaction

1) Protein A has a binding site for ligand X with a dissociation equilibrium constant of 4.0 x 10-8 The association equilibrium constant for ligand X and protein A is: