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Water-reactive substances [1] are those that spontaneously undergo a chemical reaction with water, often noted as generating flammable gas. [2] Some are highly reducing in nature. [ 3 ] Notable examples include alkali metals , lithium through caesium , and alkaline earth metals , magnesium through barium .
The most reactive metals, such as sodium, will react with cold water to produce hydrogen and the metal hydroxide: 2 Na (s) + 2 H 2 O (l) →2 NaOH (aq) + H 2 (g) Metals in the middle of the reactivity series, such as iron , will react with acids such as sulfuric acid (but not water at normal temperatures) to give hydrogen and a metal salt ...
Although it is commonplace to make statements that "substance X is reactive," each substance reacts with its own set of reagents. For example, the statement that "sodium metal is reactive" suggests that sodium reacts with many common reagents (including pure oxygen, chlorine, hydrochloric acid , and water), either at room temperature or when ...
The metal reacts with the water first, breaking the hydrogen bonds in the water and producing hydrogen gas; this takes place faster for the more reactive heavier alkali metals. Second, the heat generated by the first part of the reaction often ignites the hydrogen gas, causing it to burn explosively into the surrounding air.
Some other reactive metals, such as aluminium and beryllium, are oxidized by water as well, but their oxides adhere to the metal and form a passive protective layer. [94] Note that the rusting of iron is a reaction between iron and oxygen [ 95 ] that is dissolved in water, not between iron and water.
Reaction with nitrogen. Only Be and Mg form nitrides directly. 3Be + N 2 → Be 3 N 2 3Mg + N 2 → Mg 3 N 2. Reaction with hydrogen. Alkaline earth metals react with hydrogen to generate saline hydride that are unstable in water. Ca + H 2 → CaH 2. Reaction with water. Ca, Sr, and Ba readily react with water to form hydroxide and hydrogen gas.
Metal aqua ions are often involved in the formation of complexes. The reaction may be written as pM x+ (aq) + qL y− → [M p L q] (px-qy)+ In reality this is a substitution reaction in which one or more water molecules from the first hydration shell of the metal ion are replaced by ligands, L. The complex is described as an inner-sphere complex.
The eutectic mixture consists of 77% potassium and 23% sodium by mass (NaK-77), and it is a liquid from −12.6 to 785 °C (9.3 to 1,445.0 °F), and has a density of 0.866 g/cm 3 at 21 °C (70 °F) and 0.855 g/cm 3 at 100 °C (212 °F), making it less dense than water. [3] It is highly reactive with water and is stored usually under hexane or ...