Cobalt Chloride Paper (Container 100 sheets)

This cobalt chloride paper comes in a container of 100 sheets and is a simple indicator for detecting moisture, water and humidity in chemistry and biology. It gives students an affordable, visual way to see chemical hydration in action.

How the Colour Change Works

The paper works through the reversible hydration of cobalt(II) chloride (CoCl₂):

• Blue (anhydrous): In dry conditions, the paper stays a deep sky blue.
• Purple (dihydrate): As it starts to absorb moisture, it passes through a purplish stage.
• Pink/white (hexahydrate): When fully hydrated by direct contact with liquid or high humidity (typically 50% RH or higher), it turns a distinct light pink or white.
• Reversible: You can reset the paper to blue by warming it gently in an oven (around 50°C) or with a hair dryer to drive off the water.

Common School Experiments

• Transpiration: Students clip the paper to the top and bottom of a leaf to show that water vapour is lost mainly through the stomata on the underside.
• Humidity checks: Testing the humidity in different parts of a classroom or inside sealed containers.
• Leak detection: In physics and plumbing labs, strips are placed near joints to find tiny cracks or water leaks.

Storage and Handling

• Keep it sealed: The paper is highly hygroscopic (it absorbs moisture), so keep the container tightly closed. Even 55% humidity is enough to cause a slow, unwanted colour change.
• Use forceps: Moisture from your skin can trigger the colour change, so handle the sheets with forceps or tweezers.
• Safety: Cobalt(II) chloride is toxic if swallowed. Students should wash their hands after use.

Specifications

• Pack size: 100 sheets
• Material: Paper
• Strips: About 48mm x 6mm
• Product of India