• Question: I think my science teacher gets annoyed with me for asking so many questions i guess it just takes everything longer to stick in my head but one question i never understood the answer to is my teacher showed my class this demonstration using test tubes, lime water and a straw i was wondering if you knew the demonstration i am talking about and if you can explain how it works? sorry if you dont know the demo im not very good at explaining

    Asked by SianConnell14 to Clare, Glafkos, Paul, Samantha on 11 Mar 2015.
    • Photo: Glafkos Havariyoun

      Glafkos Havariyoun answered on 11 Mar 2015:

      Aaa the detection of carbon dioxide test!

      Basically I think you make some lime water by adding calcium hydroxide to water. Put a straw in the test tube with the lime water and then starting blowing into the tube using the straw. Now you know that the air coming out of your breathe contains Co2 right? The reaction which occurs between the Co2 in your breath (bubbles coming out of straw) and the water results into a carbonic acid. Now the lime water reacts and neutralizes the acid and forms a calcium carbonate (limestone) ion which is insoluble and presipitates . For this reason the lime water turns milky. This is how you detect C02 using lime water.

    • Photo: anon

      anon answered on 11 Mar 2015:

      Keep on asking questions! Sometimes I find explanations difficult but when I see drawings and pictures that sometimes helps.

    • Photo: Clare Devery

      Clare Devery answered on 11 Mar 2015:

      Never stop asking questions!
      http://www.hometutoring.co.nz/chemistry/experiment4.php
      I had a look for the equations, because I always found that balancing chemical equations made it easier for me to see exactly what was happening. The webpage I’ve linked sets them out nicely. Let me know if you can make any more sense of it!

    • Photo: Samantha Terry

      Samantha Terry answered on 11 Mar 2015:

      keep asking questions! I think Glafkos answered it well.

    • Photo: Paul Booker

      Paul Booker answered on 11 Mar 2015:

      That’s a new one for me!

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