Question

Which of the following statements is wrong about borax bead test? (1) Nickel salts give brown bead. (2) Copper salts give blue bead. (3) Cobalt salts give blue bead. (4) Chromium salts give yellow bead.

Short answer

Statement (4) is wrong; Chromium salts give a green bead.

Step-by-step solution

- Understand the borax bead test

The borax bead test is a qualitative method used in chemistry to identify the presence of certain metals based on the color of the bead formed when the compound is heated with borax.

- Identify color indications

Recall the typical colors each metal salt gives when subjected to the borax bead test: Nickel salts generally give brown beads, Copper salts give blue beads, Cobalt salts give blue beads, and Chromium salts give green beads.

- Compare given statements

Compare each given statement to the known outcomes of the borax bead test: 1. Nickel salts give brown bead (Correct) 2. Copper salts give blue bead (Correct) 3. Cobalt salts give blue bead (Correct) 4. Chromium salts give yellow bead (Incorrect, it should be green)

- Determine the wrong statement

Out of the given options, statement 4 is incorrect because Chromium salts do not give a yellow bead but a green bead.

Key concepts

Qualitative Analysis

Qualitative analysis in chemistry refers to identifying the chemical composition of a sample. Unlike quantitative analysis, which focuses on measuring the amounts, qualitative analysis is about understanding what substances are present. It is especially useful for detecting ions and molecules in solutions.
In the context of the borax bead test, this method helps chemists determine which metal ions are present in a given sample. The test involves heating the sample with borax, and then observing the color of the bead formed. Each metal ion produces a characteristic color, simplifying identification.
For instance:

• Nickel salts produce a brown bead.
• Copper salts result in a blue bead.
• Cobalt salts also generate a blue bead.
• Chromium salts form a green bead.

Using these colorimetric properties, qualitative analysis can be performed quickly and reliably.

Metal Salts Identification

Identifying metal salts in samples is crucial for many chemical processes and applications. The borax bead test serves as an efficient way to detect metals based on the specific colors displayed upon heating.
When the sample is heated with borax, various metals cause the bead to change into identifiable colors. Here’s how:

• Nickel: Produces a brown bead.
• Copper: Shows a blue bead.
• Cobalt: Also results in a blue bead, similar to copper but distinguishable upon closer inspection.
• Chromium: Produces a green bead, not yellow.

Recognizing these color patterns is important because metals often exhibit distinct properties that can influence chemical reactions, making identification necessary in both laboratory and industrial settings.

Colorimetric Test

Colorimetric tests involve the measurement and interpretation of colors to identify different substances. In the borax bead test, the color change is a direct visual indicator of the metal ions present.
The principle is based on how different metals react with borax. When heated, the metal oxides form colored complexes with boron, resulting in specific hues that are unique to each metal.
Important insights from colorimetric tests like the borax bead test include:

• Providing a simple and cost-efficient method for metal ion detection.
• Offering rapid results, essential for quick analysis.
• Being particularly useful in teaching scenarios to help students understand basic analytical techniques.

Understanding and correctly interpreting these colors is essential for accurate chemical analysis and further research.