halbreaktion

Halbreaktion refers to one of the two parts of a redox reaction. Redox reactions involve the transfer of electrons between chemical species, resulting in a change in their oxidation states. These reactions are conventionally divided into two half-reactions to simplify their analysis and understanding.

The first half-reaction is called the oxidation half-reaction. In this process, a chemical species loses electrons, and its oxidation state increases. For example, when metallic sodium (Na) reacts with chlorine gas (Cl2) to form sodium chloride (NaCl), the sodium atom loses an electron to become a sodium ion (Na+). This can be represented as Na -> Na+ + e-. This represents the oxidation half-reaction where sodium is oxidized.

The second half-reaction is called the reduction half-reaction. In this process, a chemical species gains electrons, and its oxidation state decreases. Continuing the sodium chloride example, the chlorine molecule gains electrons to form chloride ions (Cl-). This can be represented as Cl2 + 2e- -> 2Cl-. This represents the reduction half-reaction where chlorine is reduced.

By combining the oxidation and reduction half-reactions, the overall balanced redox reaction is obtained. In the case of sodium and chlorine, the overall reaction is 2Na + Cl2 -> 2NaCl. The concept of half-reactions is crucial in electrochemistry, where it helps in understanding the processes occurring at the anode (oxidation) and cathode (reduction) of an electrochemical cell. It also aids in balancing complex redox equations in solution.