Final answer:
The total number of electrons exchanged in the reaction 2 Fe₃+ (aq) + 3 Cu(s) = 2 Fe(s) + 3 Cu₂+(aq) is 6 electrons, since 6 electrons are gained by iron and 6 are lost by copper. So, option (b) is correct.
Step-by-step explanation:
To determine how many electrons are exchanged in the reaction 2 Fe₃+ (aq) + 3 Cu(s) = 2 Fe(s) + 3 Cu₂+(aq), we need to look at the oxidation states of the metals before and after the reaction. Iron (Fe) is going from a +3 oxidation state to a 0 oxidation state, meaning it is gaining 3 electrons. Copper (Cu) is going from a 0 oxidation state to a +2 oxidation state, meaning it is losing 2 electrons.
Since the reaction involves 2 moles of iron, this would involve 2 moles x 3 electrons/mole of iron = 6 electrons gained by iron. For copper, the reaction involves 3 moles of copper, which corresponds to 3 moles x 2 electrons/mole of copper = 6 electrons lost by copper.
The total number of electrons exchanged in the reaction is the sum of electrons gained by iron and lost by copper, which is 6 electrons. Therefore, the correct answer is (b) 6.