Question 30
In Activity 7E, 5 g of sodium hydrogen carbonate is gently heated in a test tube. A delivery tube carries the gas into limewater. The solid is heated for at least two minutes. Hold a piece of cobalt chloride paper near the mouth of the test tube while heating. Observe any colour change in the cobalt chloride paper. Cobalt chloride paper is used to detect the presence of water vapour. When it comes into contact with water, it changes colour from blue to pink.
Work in groups of four under teacher supervision. Wear safety goggles and suitable gloves. Secure the apparatus, keep the delivery tube unblocked and point tubes away from people. Remove the delivery tube from limewater before stopping heating to prevent suck-back. Handle cobalt chloride paper with gloves/tongs and dispose of it as instructed by the teacher.
Work in groups of four under teacher supervision. Wear safety goggles and suitable gloves. Secure the apparatus, keep the delivery tube unblocked and point tubes away from people. Remove the delivery tube from limewater before stopping heating to prevent suck-back. Handle cobalt chloride paper with gloves/tongs and dispose of it as instructed by the teacher.
