British Sign Language Glossaries of Curriculum Terms

BSL App Logo

BSL Chemistry Glossary - lime water - Definition

We use Lime Water to detect the presence of Carbon Dioxide gas (CO₂). Sometimes during an experiment a reaction you might see bubbling and gas being given off and you want to know which gas it is - it might be CO₂ or H₂ or O₂ so we need a test to help us and Lime Water is good for detecting CO₂.

Watch what happens when I breathe out CO₂ through this straw. Did you notice how the CO₂ in my breath turned the Lime Water cloudy? That is how we test for CO₂ by using Lime Water.

The Lime Water is made up of Calcium Hydroxide and when it mixes with CO₂ it turns cloudy. This is a good way to test whether CO₂ has been produced as part of a reaction by channelling it through a tube into Lime Water to see whether it turns cloudy.