1. Biology Mabel Goh (7) Joanna Han (8) Lim Zhi Jun (13) Low Hui Ting (14) Done by:
2. Aim To compare the rates of transpiration of the upper and lower surfaces of a leaf.
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6. This experiment should be carried out on a warm, dry day. If the atmosphere is damp, e.g. early in morning, the experiment may not be carried out successfully since the cobalt chloride papers will turn pink the moment they come into contact with damp air. In this case, cobalt thiocyanate can be used. Use a plant with stomata mainly on the lower surface of the leaves. Cobalt chloride paper is blue when dry and turns pink when it comes into contact with water vapour. Descriptions
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8. CoCl 2 . 2H 2 O + 4H 2 O CoCl 2 . 6H 2 O CoCl 2 + 2H 2 O CoCl 2 . 2H 2 O (Blue to purple) (Purple to pink) CoCl 2 + 2H 2 O CoCl 2 . 2H 2 O (Blue to purple)
