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What Happens When Metal Reacts with Water!

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Last updated date: 15th Jul 2024
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Reaction of Metal with Water: An Introduction

Not every metal reacts with water in a similar ratio. Various metals react with water in distinct ways. Metals like potassium and sodium interact with water so violently that if left out in the open, they will catch fire. Therefore, they are kept submerged in kerosene oil to safeguard them and stop unintentional fires.

Metals like magnesium, aluminium, zinc, lead, etc. have a thin oxide layer covering their surfaces at room temperature. The shielding oxide layer stops the metal from oxidising any further. Hence, this article on what happens when metal reacts with water gives more in depth information on how metals react with water with certain examples.

Reaction of Metal with Water

Hydrogen gas and metal oxides are produced when metal reacts with water. Metal hydroxide is created when soluble metal oxides are dissolved in water. However, not all metals react with water. The basic expression for this reaction is given below:

\[Metal + Water \to Metal\;Oxide + Hydrogen\]

Which Metals React Readily with Cold Water?

Sodium (Na), Potassium (K), and Calcium (Ca) are the metal which reacts readily with cold water. The reactions on how metals react with water is explained below.

Which Metals React Readily with Hot Water?

Magnesium metal does not react with cold water however it reacts readily with hot water. Its reactivity and formation was explained in detail in the following section.

Reaction of Sodium and Potassium with Water

Cold water and metals, like sodium and potassium, react vigorously. Na and K metals react with cold water and produce sodium hydroxide (NaOH) and potassium hydroxide (KOH).

\[2K\left( s \right) + 2{H_2}O\left( l \right) \to 2KOH\left( {aq} \right) + {H_2}\left( g \right) + Heat\;Energy\]

\[2Na\left( s \right) + 2{H_2}O\left( l \right) \to 2NaOH\left( {aq} \right) + {H_2}\left( g \right) + Heat\;Energy\]

Reaction of Calcium (Ca) Metal with Water

Calcium reacts less violently with cold water compared to other metals. Ca reacts with cold water and produces calcium hydroxide Ca(OH)2.

\[Ca\left( s \right) + 2{H_2}O\left( l \right) \to Ca{(OH)_2}\left( {aq} \right) + {H_2}\left( g \right)\]

Reaction of Magnesium (Mg) Metal with Water

Hot water causes Mg to react violently. Mg metal reacts with hot water to produce magnesium hydroxide (MgOH).

\[Mg\left( s \right) + 2{H_2}O\left( l \right) \to Mg{\left( {OH} \right)_2}\left( {aq} \right) + {H_2}\left( g \right)\]

Reaction of Aluminium (Al) Metal with Water

Aluminium does not react with hot and cold water. Steam, though, causes it to react. Al reacts with steam to produce aluminium oxide (Al2O3).

\[2Al\left( s \right) + 3{H_2}O\left( g \right) \to A{l_2}{O_3}\left( s \right) + 3{H_2}\left( g \right)\]

Reaction of Iron (Fe) Metal with Water

Iron also does not react with both cold and hot water. The slow and gradual reaction of iron with cold water takes a while to become noticeable. However, when Fe reacts with steam iron oxide (Fe3O4) is produced.

\[3Fe\left( s \right) + 4{H_2}O\left( g \right) \to F{e_3}{O_4}\left( s \right) + 4{H_2}\left( g \right)\]

Reaction of Zinc (Zn) Metal with Water

Cold water does not cause zinc to react. However, when steam is applied to Zn metal, hydrogen gas and zinc oxide (ZnO) is produced.

\[Zn\left( s \right) + {H_2}O\left( g \right) \to ZnO\left( s \right) + {H_2}\left( g \right)\]

Interesting Facts

  • As calcium hydroxide is only moderately soluble in water, when the solution is saturated, solid calcium hydroxide begins to emerge, and the solution begins to turn milky.

  • In response to the hydrogen gas bubbles that are stuck to the metal's surface as a result of the reaction, calcium and magnesium begin to float.

  • The standard equipment that is utilised to react calcium with water and capture the gas, the same apparatus cannot be used for sodium and potassium since their reactions are very vigorous compared to calcium.

Key Features to Remember

  • Metal oxide and hydrogen gas is created when a metal and water reacts together.

  • Metal + water = metal oxide + hydrogen is the fundamental equation for the metal reaction with water.

  • Cold water and the metals sodium, potassium, and calcium quickly react to form hydroxides.

  • Magnesium reacts with hot water rather than cold water to form hydroxide.

  • Oxides are produced when zinc, aluminium, and steam react. Cold water and iron react very slowly and may take days to complete. However, Iron oxide is created when iron combines with steam.

Competitive Exams after 12th Science

FAQs on What Happens When Metal Reacts with Water!

1. Explain the reactivity of less active and more active metals with water?

With water, metals behave in a different manner. The creation of bubbles increases with the strength of the reaction. Metals that are less active react readily with hot water. Certain metals are more reactive than other metals because they release their electrons relatively easily. The reactivity series of metals can be formed by ranking metals as per their degree of reactivity. Metals easily combine with water and weak acids, releasing hydrogen gas in the process. In general, non-metal atoms do not react with water at all.

2. How can water help metals dissolve?

If we choose the appropriate metal, water can dissolve it easily. In the activity series, metals are arranged according to their capacity to eject other elements from water. The metals swap positions with H2 in water or acids. The metal atoms dissolve in water because they are no more connected to the original source of the H2, which evaporates as a gas. The highly active metals have the ability to remove hydrogen from the water directly. Hence, when these metals dissolve in normal water, hydrogen gas is released.

3. What are metals which do not react with water?

Silver, lead, copper, and gold are the metals that do not react with water in any way. In theory, a metal that is placed above the hydrogen element in the reactivity series ought to be capable of separating oxygen from water to produce hydrogen gas. This type of reaction to produce hydrogen gas for metals with water will not be possible if metals are placed below the hydrogen element in the activity series. Thus, metals mentioned above do not react with water at all.