Fig. 1 shows the results from a student testing four metals with sulfate solutions. Each test tube was kept at the same temperature and contained the same v...
Question 1 Report
Fig. 1 shows the results from a student testing four metals with sulfate solutions. Each test tube was kept at the same temperature and contained the same volume of solution. A reaction is shown by a metal coating or a change in the solution. The student uses the results to compare the reactivity of magnesium, zinc, iron and copper.
(a) State which test tube shows no displacement reaction. [1]
(b) Give two observations expected in test tube B. [2]
(c) Complete the equation for the reaction in test tube B.
Zn + FeSO4 → ........................................ [2]
(d) Use Fig. 1 to give the four metals in order of decreasing reactivity. [3]
Answer Details
(a) The test tube containing copper and magnesium sulfate shows no displacement reaction. Copper is less reactive than magnesium, so it cannot displace magnesium from its sulfate solution. [1]
(b) In the tube containing zinc and iron sulfate, an iron metal coating or deposit forms on the zinc. The solution becomes pale green as iron sulfate is formed from the initially colourless zinc sulfate solution. [2]
(c)
\[\mathrm{Zn+FeSO_4\rightarrow ZnSO_4+Fe}\]
Zinc is more reactive than iron, so zinc displaces iron from iron sulfate. [2]
(d) The metals in decreasing reactivity are:
magnesium > zinc > iron > copper
Each reaction shows that the added metal is more reactive than the metal ion it displaces; the lack of reaction with magnesium sulfate places copper below magnesium. [3]
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