Chapter U5.18, Problem 7E

Interpretation Introduction

Interpretation:Position of cobalt with respect to iron in the activity series is to be determined.

Concept Introduction:Some metals are more active than others. By combining different metals and metal ions, one can experimentally determine which metals are more active than other metals. This gives an activity series in which metals can be arranged in order of their activity. More active metals are placed at the top of the list and less active ones are at the bottom of the list.

Answer to Problem 7E

Cobalt can be placed below iron in the activity series.

Explanation of Solution

The activity series gives list of metals which are more active than other metals. Metals on top of the list like potassium, sodium, calcium are more active than those lower on the list such as iron, nickel, copper etc. More active metals at the top of the list will always displace less active metals below.

If cobalt ions are replaced by iron to form iron ions and solid cobalt, then iron is more active than cobalt. More active metal forms cations while less active metal is reduced to a solid. So cobalt should be placed below iron in the activity series.

Conclusion

More active metals are easily oxidized whereas less active metals are easily reduced. A metal high in the activity series reacts vigorously with compounds, readily gives up electrons to form cations and are easily corroded.