Thursday, November 23, 2017

Grade 3 DNT - secret card-15'th Nov 2017



Students were given blank papers each and were asked to write on it with lemon juice using cotton and let it dry.  Nothing was visible once it dried.  Then when hot air was blown on the write up,  it turned to a slight brown colour and could be read. 
When they wrote the message using the lemon juice, carbon-based compounds in the juice were absorbed into the papers fibers. The added heat caused some of the chemical bonds to break down in the dried juice and some carbon was cut loose. When the carbon came into contact with air, it burned or oxidised and the substance turns light or dark brown. 
Children understood the process of oxidation. 





No comments:

Post a Comment