Practice Problem 1

Predict whether zinc metal should dissolve in acid.

Answer

Zinc will dissolve in acid if the metal is a strong enough reducing agent to reduce H+ ions to H2 gas.

Zn(s) + 2 H+(aq) -----> Zn2+(aq) + H2(g)

Zinc is a stronger reducing agent than H2, and the H+ ion is a stronger oxidizing agent than the Zn2+ ion.

Zn(s) + 2 H+(aq) -----> Zn2+(aq) + H2(g)  
stronger
reducing
agent		   stronger
oxidizing
agent		   weaker
oxidizing
agent		   weaker
reducing
agent		  

Zinc therefore should dissolve in acid.