Question

1. If the sample of the complex ion compound that you prepared had not thoroughly dried, but contained traces of water or ethanol would this make your determination of the moles NH 3 /g and moles Ni 2+ /g too high, too low, or would it not affect your results at all? Would this make your determination of the value of x too high, too low or would it not affect your result at all? Explain

2. After the NH 3 molecules acted as Bronsted bases in the reaction with aqueous HCl they became NH 4 + cations. Explain why NH 3 can function as a ligand with Ni 2+ while NH 4 + cannot function as a l igand with Ni 2+ . Use structures to illustrate your answers.

3. Copy the structure of EDTA 4 - from your textbook and circle all six atoms that act as Lewis bases. Why does EDTA 4 - cease to function as a chelating ligand if acid is added to the solution?

Answer 1

1 ) if the sample of the complex ion compound had not throughly dried then it will affect our results , that is the amount of complex formed will be more in weight than the amount of therotical complex to be formed and it will affect the determination of moles of NH3/g . High at NH3/g and High at Ni2+

2) NH3 + HCl --------------> NH4⁺ + Cl^-,

ammonia is acts as a ligand because it has HOMO ( Electron density ) , the lone pairs of nitrogen atom donates its electrons to the electropositive cental metal ion.

in the synthesis of metal complex the metals are electropositive (LUMO), and it reacts with electron donar atoms , so ammonia acts as a ligand. the NH4+ ION is electron deficient and it does not acts as a ligand ( the central metal is also electropositive)

Ni²⁺+ 4 NH3 ----------> [Ni(NH3)4]²⁺

3)