Question

If a compound absorbs in the wave length region corresponding to green, then it will appear (a) red (b) violet (c) green (d) orange

Short answer

The compound will appear red.

Step-by-step solution

Identify Color Absorbed

The given problem states that the compound absorbs in the green wavelength region. In the visible spectrum, green light has a wavelength range of approximately 520–560 nm.

Understand Complementary Colors

In color theory, a compound that absorbs light of a certain color will appear as the complementary color to the one it absorbs. The complementary color of green is red.

Determine the Appearance Color

Since the compound absorbs green light, it will reflect the colors that constitute the mixture of all other colors minus green. Thus, it will appear red, which is the complementary color of green.

Key concepts

Complementary Colors

Understanding complementary colors is a fascinating aspect of color theory. When a compound absorbs a certain color of light, it doesn't just disappear. Instead, the compound often appears as the color opposite to the absorbed color on a color wheel, which we call the 'complementary color.' For example, if a substance absorbs green light, it means green wavelengths are not reflected, and the complementary color, red, becomes visible to our eyes.

In simple terms, complementary colors are pairs of colors that, when combined, cancel each other out. This means they produce a grayscale color like white or black when mixed. However, in terms of light absorption, the solid appearing color will be the one opposite to what is absorbed.

• Red and green are complementary colors
• Blue and orange are complementary colors
• Yellow and violet are complementary colors

Understanding these pairs helps not only in chemistry but also in art and design, where mixing colors achieves particular visual effects.

Visible Spectrum

The visible spectrum is the range of light wavelengths that the human eye can detect. It falls within a small range of the electromagnetic spectrum, specifically between about 380 nm to 750 nm. This is the only portion of the electromagnetic spectrum that is visible to the human eye.

Within the visible spectrum, different wavelengths correspond to different colors. This is like a rainbow, spanning from violet at around 380 nm to red at around 750 nm.

• Violet: ~380-450 nm
• Blue: ~450-495 nm
• Green: ~495-570 nm
• Yellow: ~570-590 nm
• Orange: ~590-620 nm
• Red: ~620-750 nm

Each wavelength within this spectrum is perceived as a distinct color by our eyes and brain, thanks to the way our photoreceptors absorb and interpret light. This process is critical for understanding both natural and synthetic coloring in materials.

Wavelength and Color

Wavelength is a fundamental concept when it comes to understanding color in chemistry. Wavelength refers to the distance between two consecutive peaks of a wave and is typically measured in nanometers (nm). In the realm of visible light, each color corresponds to a specific range of wavelengths.

For example, green light typically involves wavelengths of about 520 to 560 nm. When a compound absorbs light in this region, it does not reflect green light. Instead, it reflects what is known as its complementary color.

This is because visible light is composed of various colors mixed together, and when one color is removed, the compound appears as the mix of the remaining colors which sum up to its complementary color.

• A shorter wavelength (around 400 nm) is perceived as violet.
• As you move to longer wavelengths, you start seeing blue, green, yellow, orange, and eventually red (around 700 nm).

Understanding the relationship between wavelength and color helps in determining the appearance of substances and has applications in fields such as spectroscopy and optical engineering.