What do get when you mix water and one of the alkali metals?

Answer 1

An explosion, because the alkali metal react violently up when they touch water. When added to water the metal becomes a +1 ion, and the water forms OH- and H2 gas. The reaction with water is very exothermic, fast and violent. If a lump of lithium, sodium or potassium is placed in cold water, the metal floats; it may melt and move around the surface of the water with 'fizzing'. If universal indicator is added, it changes from green (pH 7) to purple (pH 13-14), showing an alkaline metal hydroxide was formed. The colourless gas hydrogen is also given off and pops with lit splint - but this is not the best of experiments to collect it from! The more reactive the metal, the more vigorous the reaction. Lithium and sodium do not normally cause a flame but the potassium reaction is exothermic enough to ignite the hydrogen. o 2H2(g) + O2(g) => 2H2O(l) o The hydrogen flame turns lilac due to hot potassium atoms in it. o Note: in flame tests hot lithium atoms give a crimson colour and sodium a yellow colour (more details). Rubidium, caesium and francium are very explosive with water. Down the group the reaction gets faster and more violent as the metal gets more reactive i.e. Li < Na < K < Rb < Cs < Fr. The reaction equation for sodium is in words and symbols... sodium + water ==> sodium hydroxide + hydrogen 2Na(s) + 2H2O(l) ==> 2NaOH(aq) + H2(g) and the equations are similar for any of the other Alkali Metals since they are in the same group of the Periodic Table, they behave chemically in the same way. Theoretically Francium is the most reactive and therefore the most explosive metal when in contact with water. See the Related Questions to the left for more information.

Also watch the linked videos of massive explosions due to sodium mixing with water! BOOM!!!

!!DBR!!