What is the product formed when metals react with water?

Short Answer:

When metals react with water, they form metal hydroxides and hydrogen gas. The reaction is usually more vigorous with alkali metals like sodium and potassium, while less reactive metals like iron react slowly.

For example, sodium reacts rapidly with water to form sodium hydroxide and hydrogen gas. This reaction is important in chemistry as it demonstrates the reactivity of metals and is used in producing certain compounds like alkalis.

Detailed Explanation:

Reaction of Metals with Water

Metals react with water depending on their reactivity. Highly reactive metals react quickly, producing heat, hydrogen gas, and metal hydroxides. Less reactive metals may react slowly or only with steam.

General Reaction

The general formula for metal-water reaction is:
Metal + Water → Metal Hydroxide + Hydrogen Gas

For example:

  • Sodium: 2Na + 2H₂O → 2NaOH + H₂
  • Potassium: 2K + 2H₂O → 2KOH + H₂
  • Calcium: Ca + 2H₂O → Ca(OH)₂ + H₂

Nature of Products

  1. Metal Hydroxides:
    • The metal hydroxide formed is usually alkaline (basic in nature).
    • Example: Sodium hydroxide (NaOH) is a strong base.
  2. Hydrogen Gas:
    • Hydrogen gas is released during the reaction.
    • It can be collected and tested by bringing a burning splint near the gas, producing a pop sound.

Reactivity of Metals

  • Highly Reactive Metals: Sodium, potassium, and calcium react violently with water.
  • Moderately Reactive Metals: Magnesium reacts slowly with cold water but faster with steam.
  • Less Reactive Metals: Iron and zinc react very slowly with water but readily with steam at high temperatures.
  • Least Reactive Metals: Copper, silver, and gold do not react with water.

Factors Affecting the Reaction

  1. Reactivity of Metal: Determines speed and intensity of reaction.
  2. Temperature: Higher temperature increases reaction rate.
  3. Surface Area: Finely divided metals react faster due to more exposed surface.

Importance of Metal-Water Reactions

  1. Laboratory Experiments: Demonstrates metal reactivity and production of hydrogen gas.
  2. Industrial Use: Hydrogen gas produced is used in chemical industries.
  3. Formation of Alkalis: Metal hydroxides like NaOH and KOH are important alkalis used in soaps, detergents, and chemical manufacturing.
  4. Safety Precautions: Reactions of alkali metals with water are highly exothermic and must be handled carefully.

Safety Measures

  • Always perform reactions with water and reactive metals under controlled conditions.
  • Use protective gear and conduct experiments in a safe environment.
  • Keep reactive metals like sodium and potassium away from moisture until use.
Conclusion:

When metals react with water, the products formed are metal hydroxides and hydrogen gas. The reaction depends on the reactivity of the metal and the conditions, such as temperature and surface area. This reaction is important for producing alkalis and hydrogen gas, as well as for demonstrating metal reactivity in chemistry.