Weathering Limestone - with my own breath! A classroom demonstration of how limestone is weathered (PDF)

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Students taking water samples during field work

ERN Item Type: 

  • Classroom Activities


Earth Learning Idea (ELI)


Carry out a laboratory demonstration of the first stages in the chemical weathering of limestone. Quarter-fill a small glass beaker or a boiling tube, with some water of neutral pH and add some Universal indicator. Ask what will happen if a pupil blows steadily into the water through a straw (it pays to choose the most talkative pupil to do this!). Watch what happens as the exhaling continues, and see if the water will turn acid – indicated by the colour changing from green to yellow, to orange or even to pink. Ask pupils to explain why this has happened.

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Is this tagged to NGSS by the organization?: 


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