Cambridge Secondary (7-9). Stage 7. MCE Science. Workbook - Unit 9: Chemical Reactions - Question 15

Wear eye protection and disposable gloves when handling solutions. Work under teacher supervision. Investigation 1: an iron nail is placed in about 200 cm³ of copper nitrate solution in a beaker on an electronic balance. The beaker is covered with a watch glass while it stands for a week; the watch glass is removed before the final weighing. Investigation 2: put a sheet of paper towel on the balance, and on top of that, put a small beaker and an empty dropper pipette. Zero (tare) the balance, then pour about 10 cm³ of sodium chloride solution into the beaker. Place the beaker back on the balance. Half-fill the dropper pipette with silver nitrate solution and lay it carefully back on the balance. Add the silver nitrate solution to the sodium chloride solution, then put the empty dropper back on the balance.

Are the changes you observed in the two investigations physical changes or chemical changes? Explain your answer.