The Oceans

Worksheet 3

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1. Experiment

The carbon dioxide which enters the sea reacts with the carbonate already present to form hydrogen carbonate. You can look at this reaction happening with a simple experiment.

First get a small glass of limewater (calcium hydroxide solution) from your teacher, then breathe into it with a straw. What do you see?

Your breath contains CO₂ and this CO₂ reacts with the limewater to form insoluble calcium carbonate:

Breathe into a small glass of limewater with a straw. (Photo: Hetland vgs)

This reaction is often used to show the presence of CO₂.

If you keep blowing into the solution, the white precipitate disappears and the solution becomes clear again. The is the reaction which happens when CO₂ enters sea water:

What do you see? (Photo: Hetland vgs)

2. GAIA and CLAW

James Lovelock, who launched the Gaia hypothesis, in front of a statue of the Greek goddess of the Earth, Gaia. (©Copyright photo EFN - Environmentalists For Nuclear Energy www.ecolo.org)

Find out more about GAIA and the CLAW hypothesis.

Use an encyclopedia, the Internet or a science book (your teacher can help you find material).

Authors: Ellen K. Henriksen and Camilla Schreiner - University of Oslo - Norway. Scientific reviewer: Lucinda Spokes - Environmental Sciences, University of East Anglia, Norwich - U.K. Last update: 2004-03-27.

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