ANS:C - Lead chromates

Lead chromates are a yellow pigment. Lead chromates are a yellow pigment commonly used in various applications due to their vibrant color and excellent stability. Here’s a detailed explanation:

Composition and Structure:

1. Chemical Formula: Lead chromate has the chemical formula PbCrO₄, which consists of lead (Pb), chromium (Cr), and oxygen (O).
2. Crystalline Structure: It typically forms as a bright yellow powder or solid with a crystalline structure, contributing to its pigmentation properties.

Properties:

1. Color: Lead chromate is known for its strong yellow color, making it an ideal choice for pigments in paints, coatings, and plastics.
2. Stability: It exhibits good chemical stability and resistance to fading when exposed to light, ensuring long-lasting color in applications.
3. Opacity: Lead chromate provides excellent opacity, allowing for effective coverage in coatings and finishes.

Uses:

1. Paints and Coatings: Due to its bright yellow hue, lead chromate is widely used in industrial and artistic paints, as well as protective coatings for metal surfaces.
2. Plastics and Inks: It is also utilized in colored plastics and inks, contributing to the vivid color in various products.
3. Historical Use: Lead chromate has historically been important in art and manufacturing, although its use has declined due to health concerns associated with lead exposure.

Health and Environmental Concerns:

While lead chromates are effective pigments, they contain lead, which is toxic and poses health risks. This has led to regulations and restrictions on their use in many applications, encouraging the development of safer alternatives.

Summary:

Lead chromates are significant yellow pigments valued for their brightness, stability, and opacity, though their use is increasingly limited due to environmental and health considerations.