Group 7: the halogensIB MYP Chemistry: Mind map

Exam questions on Group 7: the halogens

1. A nurse in a clinic in Nairobi cleans a patient's cut with a brown iodine solution before applying a dressing. Iodine is a Group 7 element, one of the halogens.
   Explain why the nurse uses iodine solution on the cut.2 marks
2. A chemist adds a few drops of orange bromine water to a colourless solution of potassium iodide, and the mixture turns brown. She then adds bromine water to a colourless solution of potassium chloride and sees no change.
   Write the balanced symbol equation for the reaction of bromine with potassium iodide.2 marks
3. A data book gives these melting and boiling points. Chlorine melts at −101 °C and boils at −34 °C. Bromine melts at −7 °C and boils at 59 °C. Iodine melts at 114 °C and boils at 184 °C. A chemist wants to predict the properties of fluorine, which lies above chlorine in Group 7. Room temperature is 25 °C.
   State the physical state of chlorine, bromine and iodine at 25 °C.3 marks