Water turns blue cobalt chloride paper:

• A) No change
• B) Red
• C) Pink
• D) orange

When cobalt chloride paper comes into contact with water, it undergoes a specific chemical reaction that results in a noticeable color change. The correct answer to your question is A) No change. Let’s delve into the details to understand why this is the case.

Understanding Cobalt Chloride Paper

Cobalt chloride paper is a type of indicator used primarily to detect the presence of water. It contains cobalt(II) chloride, which is a hygroscopic compound, meaning it readily absorbs moisture from the air. When dry, cobalt chloride paper appears blue.

Reaction with Water

When cobalt chloride paper is exposed to water, it does not change color in the way that other indicators might. Instead, it remains blue because the cobalt(II) chloride is already in a hydrated form when it absorbs water. The blue color indicates that the paper is dry, and the presence of moisture does not alter this color.

Color Changes in Other Indicators

To clarify, let’s compare cobalt chloride paper with other common indicators:

• Litmus Paper: Turns red in acidic solutions and blue in basic solutions.
• Phenolphthalein: Turns pink in basic solutions and remains colorless in acidic solutions.

Unlike these indicators, cobalt chloride paper is specifically designed to indicate dryness rather than acidity or alkalinity.

Practical Applications

This property of cobalt chloride paper makes it useful in various applications, such as:

• Determining humidity levels in the environment.
• Indicating the dryness of certain materials.

In summary, when cobalt chloride paper is exposed to water, it remains blue, confirming that it is a reliable indicator of dryness rather than moisture presence. This unique characteristic sets it apart from other pH indicators, making it a valuable tool in scientific and practical applications.