Zinc-carbon battery - Chemistry

In a zinc-carbon dry-cell battery, the zinc shell of the battery is the negative terminal. The zinc is oxidized using the half-equation:

$$Zn(s) → Zn_2+(aq) + 2e^- = -0.76V$$

The positive terminal is the carbon (graphite) rod surrounded by the manganese(IV) containing powder. The manganese is combined with carbon powder to increase electrical conductivity.

$$2MnO_2(s) + H_2(g) \Rightarrow Mn_2O_3(s) + H_2O(l)$$

Where $$H_2$$ is provided by $$NH_4^{+}(aq)$$ :

$$2NH_4^{+}(aq) + 2e^- \Rightarrow H_2(g) + 2NH_3(aq)$$

Then the $$Nh_3$$ bonds with the $$Zn^{2+}$$

The overall reaction is:

$$Zn(s) + 2MnO_2(s) + 2NH_4^{+}(aq) \Rightarrow Mn_2O_3(s) + Zn(NH_3)^{2+}(aq) + H_2O(l)$$


 * Zinc-carbon battery
 * Zinc-carbon battery - Technical Information