Question

Of the reactions below, only ________ is not spontaneous. A. Zn (s) + 2HI (aq) → ZnI2(aq) + H2 (g) B. 2Ag (s) + 2HNO3 (aq) → 2AgNO3 (aq) + H2 (g) C. Mg (s) + 2HCl (aq) → MgCl2 (aq) + H2(g) D. 2Ni (s) + H2SO4 (aq) → Ni2SO4 (aq) + H2 (g) E. 2Al (s) + 6HBr (aq) → 2AlBr3 (aq) + 3H2 (g)

Answer 1

2Ag (s) + 2HNO3 (aq) → 2AgNO3 (aq) + H2(g)

Step-by-step explanation:

Usually, metals displace hydrogen from dilute acids to form the corresponding salt of the metal and hydrogen. This in turn depends on the position of the metal in the electrochemical series. Metals below hydrogen in the electrochemical series cannot spontaneously displace it from dilute acids. Silver is below hydrogen in the electrochemical series, hence it cannot spontaneously displace hydrogen from dilute nitric acid as shown in the answer.