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 is the decomposition of a liquid using electricity. When ionic compounds are molten or dissolved in water the ions are free to move. When sulfuric acid is electrolysed, hydrogen is produced at the cathode (negative electrode) and oxygen at the anode (positive electrode). Aluminium is extracted from the mineral bauxite using the process of electrolysis.