Science Projects or Science Experiments: Grades 5 & 6
Limewater Test - To check for carbon dioxide in your breath
Lime Water Breath Experiment
Using lime water is a fun and easy way to test for the presence of carbon dioxide. The exhaled carbon dioxide is used to produce a precipitate of calcium carbonate with the lime water,
Limewater & CO2
Carbon dioxide dissolves in water to form carbonic acid (H2CO3).
Lime water is a solution of calcium hydroxide (Ca(OH)2).
They react to form calcium carbonate (CaCO3) and water. Calcium carbonate is insoluble and forms a white precipitate. If CO2 continues to be passed, more carbonic acid forms, which then reacts with with the calcium carbonate to form calcium hydrogencarbonate, which is soluble, so the precipitate is seen to dissolve
Junior Cert - Science experiments - Biology
OB11 CO2 levels in inhaled and exhaled air. 0:00 - 2:29
OB49 To show that starch is produced in plants 2:30 - 5:10
OB58 Conditions Necessary for germination 5:13 - 7:16
OB65 To show the presence of micro-organisms 7:18 - 9:02
Carbon dioxide dissolves in water
Here is some pure water, which has a pH of 7, shown by using this testing paper and matching the color to the chart on the side of the box.
If I take a straw and blow into the water, what gases are going into the water?
The one I am interested in is carbon dioxide, which can dissolve in water and react to form an acid.
CO2(g) + H2O(l) → H2CO3(aq) → H+(aq) + HCO3−(aq)
So after I blow into the water several times, I should have a solution which is more acid than it was before. Let's check by retesting the pH of the solution. It is now down to 5, rather than the 7 it was as pure water. pH 5 is an acid, so the carbon dioxide has dissolved in the water and reacted.
Thus my chemical reaction really has made hydrogen ions in the water, meaning that the carbon dioxide gas dissolved and reacted.
CO2(g) + H2O(l) → H+(aq) + HCO3−(aq)
What does this mean about rain which passes through air with CO2 in it?
We welcome your feedback, comments and questions about this site or page. Please submit your feedback or enquiries via our Feedback page.