Final answer:
The stoichiometric coefficient for aluminum when aluminum metal reacts with aqueous cobalt(II) nitrate to form aqueous aluminum nitrate and cobalt metal is 3.
Step-by-step explanation:
The student asked about the stoichiometric coefficient for aluminum in the reaction where aluminum metal reacts with aqueous cobalt(II) nitrate to form aqueous aluminum nitrate and cobalt metal. To balance the equation, one needs to ensure that there are equal numbers of each type of atom on both sides of the equation.
Aluminum, when part of an ionic compound, adopts a charge of +3, so aluminum nitrate is written as Al(NO3)3. Therefore, the balanced equation for the reaction between aluminum and cobalt(II) nitrate (Co(NO3)2) is:
3 Al (s) + 2 Co(NO3)2 (aq) → 2 Co (s) + 3 Al(NO3)3 (aq)
The stoichiometric coefficient for aluminum in the balanced reaction is 3.