Question

Dimethyl glyoxime in a suitable solvent was refluxed for 10 minutes with pure pieces of nickel sheet, it will result in (a) blue precipitate (b) yellow precipitate (c) red precipitate (d) no precipitate

Short answer

(c) red precipitate

Step-by-step solution

Understanding Dimethyl Glyoxime and Nickel

Dimethyl glyoxime (DMG) is a reagent commonly used in analytical chemistry to test for the presence of nickel ions. When nickel is present, DMG forms a complex with the nickel ion.

Identifying the Reaction Outcome

The reaction of dimethyl glyoxime with nickel ions typically yields a nickel complex that has a distinct color. Specifically, the reaction of nickel with dimethyl glyoxime results in the formation of a red precipitate, characteristic of this specific nickel complex.

Explanation of Refluxing

Refluxing is a process often used in chemical reactions to ensure complete reaction or extraction. In this exercise, refluxing the nickel with dimethyl glyoxime in a solvent promotes the formation of the nickel dimethyl glyoxime complex, resulting in a precipitate.

Conclusion and Answer

Based on the standard reaction between dimethyl glyoxime and nickel, under reflux conditions, a red precipitate of nickel dimethylglyoximate is typically formed.

Key concepts

Dimethyl Glyoxime

Dimethyl Glyoxime (DMG) is a well-known chemical reagent in the field of analytical chemistry. It is particularly celebrated for its ability to form complexes with nickel ions. These complexes are stable and useful for the qualitative and quantitative determination of nickel.

DMG is a diketone, a compound containing two ketone groups, which confers it excellent chelating properties. The molecular structure of DMG allows it to donate electron pairs, thus forming a ligand which can tightly bind to metal ions.

When DMG interacts with nickel ions \( Ni^{2+} \), a neutral complex called nickel dimethylglyoximate is formed. This complex is generally red, making it easy to identify through simple visual inspection or photometric methods. This distinct red color is due to the unique electronic transitions within the complex, which absorb light in the visible spectrum.

This capability makes DMG an invaluable tool in detecting nickel in various samples, providing a simple yet effective method to ascertain nickel presence.

Nickel Complexes

Nickel complexes play a crucial role in both industrial and academic fields of chemistry. When we talk about complexes, we're referring to compounds made up of a central metal atom, like nickel, bonded to surrounding molecules or ions. These surrounding molecules are known as ligands, and in the case of nickel complexes, DMG can be one of these ligands.

In the specific interaction of nickel with dimethyl glyoxime, the resulting compound is a chelate, where nickel acts as the central metal ion surrounded by coordinated ligand moieties. Chelation is a multi-toothed grip that ligands like DMG exert to hold the nickel ion firmly, resulting in a highly stable structure.

Research and practical applications are drawn to this property because it introduces unique features such as color change, solubility, and magnetic properties, which can aid in a wide array of applications. For instance:

• It simplifies nickel detection and extraction from complex matrices.
• It enhances understanding of metal-ligand interactions in biological and chemical systems.
• It serves as a model for studying similar metal-ligand interactions.

Nickel complexes, especially with DMG, thus have significant importance in diverse applications, from environmental monitoring to industrial processes.

Reflux Method

The Reflux Method is a common laboratory technique used in chemistry to accelerate reactions, promoting substantial interaction between reactants. In the context of forming nickel complexes with dimethyl glyoxime, using reflux helps ensure that the reaction progresses to completion.

Essentially, reflux involves heating the mixture to boiling and then condensing the vapor back into the liquid, which is continuously returned to the reaction flask. This process maintains the system at a constant temperature, preventing evaporative losses of any volatile compounds.

Why is reflux important? Here are some key benefits:

• Reaction Efficiency: By maintaining the reaction at its optimal temperature, reflux increases the chance of reactants colliding with enough energy to result in product formation.
• Increased Yield: The conditions reduce the chance of losing reactants as vapor, maximizing the amount of product formed.
• Safety: Maintaining a closed system at a consistent temperature reduces the risk of unexpected reactions and enhances safety protocols in the laboratory.

Overall, reflux is a strategy to ensure that chemical reactions proceed swiftly and effectively, often used in both research and industrial chemical production to synthesize desired products efficiently.