1 Each square on the map is 2 cm by 2 cm (4 cm 2) and represents 1 km 2 on the surface of the earth. 2  For 1:25,000 maps, the grid lines are 4 cm apart. 3  Each square on the map is 4 cm by 4 cm (16 cm 2) and represents 1 km 2 on the surface of the earth.
+ 2 e â + 2 H + â. In the last example, H + ions (hydrogen ions) also take part in the reaction, and are provided by an acid in the solution, or by the solvent itself (water, methanol etc.). Electrolysis reactions involving H + ions are fairly common in acidic solutions.
Electrolysis of brine. Brine is a solution of sodium chloride (NaCl) and water (H 2 O). The process of electrolysis involves using an electric current to bring about a chemical change and make new chemicals. The electrolysis of brine is a large-scale process used to manufacture chlorine from salt. Two other useful chemicals are obtained during the process, sodium hydroxide (NaOH) and hydrogen (H 2). It is important that the chlorine and sodium hydroxide produced in the process are separated they react when they come into contact with each other.