A free radical chain reaction is initiated when light energy causes chlorine radicals to form as shown below. (a) Complete the equations below showing possible propagation and termination steps. (2) (b) Why is the plastic bottle used in the experiment wrapped in black tape? (1) Chloramines can be removed from water using ultraviolet light treatment. One step in the process is the formation of free radicals. State what is meant by the term free radical. (1) Another step in the process is below. State the name for this type of step in a free radical reaction. (1) Modern shellac nail varnishes are more durable and so last longer than traditional nail polish. The shellac nail varnish is applied in thin layers to the nails and then the fingers are placed under a UV lamp. (a) The Skin Care Foundation has recommended that a sun-block is applied to the fingers and hand before using the lamp. Suggest why the Skin Care Foundation makes this recommendation. (1) (b) A free radical chain reaction takes place and the varnish hardens. (i) State what is meant by the term free radical. (1) (ii) The shellac nail varnish contains a mixture of ingredients that take part in the free radical chain reaction. One of the steps in the free radical chain reaction is:
A free radical chain reaction is initiated when light energy causes chlorine radicals to form as shown below. (a) Complete the equations below showing possible propagation and termination steps. (2) (b) Why is the plastic bottle used in the experiment wrapped in black tape? (1) Chloramines can be removed from water using ultraviolet light treatment. One step in the process is the formation of free radicals. State what is meant by the term free radical. (1) Another step in the process is below. State the name for this type of step in a free radical reaction. (1) Modern shellac nail varnishes are more durable and so last longer than traditional nail polish. The shellac nail varnish is applied in thin layers to the nails and then the fingers are placed under a UV lamp. (a) The Skin Care Foundation has recommended that a sun-block is applied to the fingers and hand before using the lamp. Suggest why the Skin Care Foundation makes this recommendation. (1) (b) A free radical chain reaction takes place and the varnish hardens. (i) State what is meant by the term free radical. (1) (ii) The shellac nail varnish contains a mixture of ingredients that take part in the free radical chain reaction. One of the steps in the free radical chain reaction is:
nc-exam-questions-updated-april-2018.docx