Using the activity series provided. Which reactants will form products?

Na > Mg > Al > Mn > Zn > Cr > Fe > Cd > Co > Ni > Sn > Pb > H > Sb > Bi > Cu > Ag

1. Ag + NaNO3

2. Fe + Al2O3

3. Ni + NaCl

4. Fe + Cu (NO3) 2

All the reactions given are single displacement reactions and can only occur if the metal is more reactive than the metal in the salt. In the first equation, silver is much less reactive than sodium so no reaction occurs. Same goes for the other 2. However the last equation will occur as iron is more reactive than copper and will displace it out of solution, forming copper metal and iron nitrate. Therefore the 4th reaction will form products