Open Question
Which type of magnetic material cannot be used to make permanent magnets: a ferromagnetic substance, an antiferromagnetic substance, or a ferrimagnetic substance?
Ch.23 - Transition Metals and Coordination Chemistry
Chapter 23, Problem 23
Complete the exercises below. A complex is written as NiBr₂ • 6NH₃. a. What is the oxidation state of the Ni atom in this complex? b. What is the likely coordination number for the complex? c. If the complex is treated with excess AgNO₃ (aq), how many moles of AgBr will precipitate per mole of complex?
Verified step by step guidance1
Step 1: Determine the oxidation state of Ni in the complex NiBr₂ • 6NH₃. Start by recognizing that NH₃ is a neutral ligand and does not affect the oxidation state. Bromide (Br⁻) has a charge of -1. Since there are two bromide ions, their total charge is -2. Let the oxidation state of Ni be x. Set up the equation: x + 2(-1) = 0, and solve for x.
Step 2: Identify the coordination number of the complex. The coordination number is the number of ligand donor atoms bonded to the central metal ion. In this complex, there are 6 NH₃ molecules, each donating a pair of electrons to Ni. Therefore, the coordination number is the number of NH₃ ligands.
Step 3: Analyze the reaction of the complex with excess AgNO₃ (aq). AgNO₃ reacts with bromide ions to form AgBr, a precipitate. Determine how many bromide ions are present in one mole of the complex, as these will react with Ag⁺ ions to form AgBr.
Step 4: Calculate the moles of AgBr formed per mole of complex. Since each mole of complex contains 2 moles of Br⁻, and each Br⁻ reacts with one Ag⁺ to form one mole of AgBr, determine the total moles of AgBr precipitated per mole of complex.
Step 5: Summarize the findings. The oxidation state of Ni, the coordination number, and the moles of AgBr formed per mole of complex are determined based on the analysis of the complex and its reaction with AgNO₃.
Related Practice
Open Question
Complete the exercises below. a. Using Werner’s definition of valence, which property is the same as oxidation number, primary valence or secondary valence? b. What term do we normally use for the other type of valence? c. Why can NH₃ serve as a ligand but BH₃ cannot?
Open Question
Complete the exercises below. Which species are more likely to act as ligands? a. Positively charged ions or negatively charged ions? b. Neutral molecules that are polar or those that are nonpolar?
Open Question
Complete the exercises below. Crystals of hydrated chromium(III) chloride are green, have an empirical formula of CrCl₃ • 6H₂O, and are highly soluble. a. Write the complex ion that exists in this compound. b. If the complex is treated with excess AgNO₃ (aq), how many moles of AgCl will precipitate per mole of CrCl₃ • 6H₂O dissolved in solution? c. Crystals of anhydrous chromium(III) chloride are violet and insoluble in aqueous solution. The coordination geometry of chromium in these crystals is octahedral, as is almost always the case for Cr³⁺. How can this be the case if the ratio of Cr to Cl is not 1:6?
Open Question
Complete the exercises below. Indicate the coordination number and the oxidation number of the metal for each of the following complexes: a. Na₂ [CdCl₄] b. K₂ [MoOCl₄] c. [Co(NH₃)₄ Cl₂] Cl
Open Question
Complete the exercises below. Indicate the coordination number and the oxidation number of the metal for each of the following complexes: e. NH₄[Cr(NH₃)₂(NCS)₄]