Aluminum metal reacts with aqueous cobalt(II) nitrate to form aqueous aluminum nitrate and cobalt metal. What is the stoichiometric coefficient for aluminum when the chemical equation is balanced using the lowest, whole-number stoichiometric coefficients?

The stoichiometric coefficient for aluminum is 2

Explanation:

Step 1: Data given

Aluminum metal = Al(s)

aqueous cobalt(II) nitrate = Co(NO3)2(aq)

aluminum nitrate = Al(NO3)3

cobalt metal = Co(s)

Step 2: The unbalanced equation

Al(s) + Co(NO3)2(aq) → Al(NO3)3(aq) + Co(s)

Step 3: Balancing the equation

On the left side we have 2x NO3 (in Co(NO3)2), on the right side we have 3x NO3 (in Al(NO3)3). To balance the amount of NO3 we have to multiply Co(NO3)2 on the left side by 3 and Al(NO3)3 on the right side by 2

Al(s) + 3Co(NO3)2(aq) → 2Al(NO3)3(aq) + Co(s)

On the left side we have 3x Co (in 3Co(NO3)2 ) and on the right we have 1x Co . To balance the amount of Co we have to multiply Co on the right by 3

Al(s) + 3Co(NO3)2(aq) → 2Al(NO3)3(aq) + 3Co(s)

On the right side we have 1x Al and on the right we have 2x Al, in (2Al(NO3)3 . To balance the amount of Al we have to multiply Al on the left by 2. Now the equation is balanced.

2Al(s) + 3Co(No3)2(aq) → 2Al(No3)3(aq) + 3Co(s)

The stoichiometric coefficient for aluminum is 2