Question

Based on the literature Activity Series (Links to an external site.)Links to an external site., would you expect to observe the following reactions:

Cr(s) with HCl(aq)                             [ Select ]                       ["yes", "no"]      

Au(s) with HCl(aq)                             [ Select ]                       ["yes", "no"]      

Co(s) with Pb(NO3)2(aq)                             [ Select ]                       ["yes", "no"]      

Ca(NO3)2(aq) with Al(s)                             [ Select ]                       ["yes", "no"]      

Answer 1

These reactions can be explained based on the electrochemical series. The more reactive element displaces the less reactive

1) Cr (s) with HCl (aq)         

Theoretically YES, because chromium is located below Hydrogen in the electrochemical series and should displace Hydrogen from acidic solutions. Practically NO, because Chromium will be covered with an impermeable oxide coating and will not react with HCl

2) Au (s) with HCl(aq)

NO. Because Gold is less reactive (Located below Hydrogen in the electrochemical series)

3) Co(s) with Pb(NO3)2(aq)

YES. Because Cobalt is more reactive than Lead

4) Ca(NO₃)₂(aq) with Al(s)    

NO. Aluminium is less reactive than Calcium and cannot displace Calcium from acidic solution