The two half-reactions for the LeClanche dry cell battery are shown below. Describe the direction of spontaneous electron flow in this electrochemical cell.

Zn(s) ---> Zn2+(aq) + 2e-
2NH4+(aq) + 2e- ---> 2NH3(g) + H2(g)

Electrons flow from the anode (Zn electrode) through a wire and the electrical circuit to the cathode (Carbon electrode) which is connectd internally to the NH4^+ paste.

To determine the direction of spontaneous electron flow in an electrochemical cell, you need to consider the reduction potentials of the half-reactions involved.

In the given half-reactions:
Zn(s) ---> Zn2+(aq) + 2e- (oxidation half-reaction)
2NH4+(aq) + 2e- ---> 2NH3(g) + H2(g) (reduction half-reaction)

In electrochemical cells, electrons flow spontaneously from the species with a lower reduction potential (E° reduction) to the species with a higher reduction potential. Therefore, the direction of spontaneous electron flow is from Zn(s) to 2NH4+(aq).

To find the reduction potential of each half-reaction, you can use tables or references that provide standard reduction potentials (E° reduction). The half-reaction with a more positive E° reduction is the one that will undergo reduction, and the other half-reaction will undergo oxidation.

It's important to note that the given half-reactions are not balanced in terms of both electrons and atoms, so the reduction potentials obtained may not be directly comparable. However, based on standard reduction potentials, we can determine the direction of spontaneous electron flow.