key term - Calcium hydride

Definition

Calcium hydride (CaH₂) is an inorganic compound formed from calcium and hydrogen, known for its ability to release hydrogen gas when it reacts with water. It is categorized as a binary hydride and is notable for its reactivity with moisture, which makes it an important compound in both chemical synthesis and hydrogen storage applications.

5 Must Know Facts For Your Next Test

1. Calcium hydride can be produced through the direct reaction of calcium metal with hydrogen gas at elevated temperatures.
2. When calcium hydride comes into contact with water, it generates calcium hydroxide and hydrogen gas, making it useful in generating hydrogen for fuel cells.
3. Calcium hydride serves as a drying agent due to its ability to absorb moisture from the environment, which helps keep chemicals dry during storage.
4. This compound is typically a grayish-white solid and has a high melting point of around 800 °C (1472 °F), indicating its thermal stability.
5. In addition to its use in hydrogen production, calcium hydride is also used in organic synthesis as a reducing agent.

Review Questions

• How does calcium hydride react with water, and what are the products of this reaction?
  • When calcium hydride reacts with water, it produces calcium hydroxide and hydrogen gas. The reaction can be represented by the equation: $$ ext{CaH}_2 + 2 ext{H}_2 ext{O} ightarrow ext{Ca(OH)}_2 + ext{H}_2$$. This reaction is significant because it not only generates hydrogen gas but also illustrates how calcium hydride behaves as a strong reducing agent.
• Discuss the applications of calcium hydride in industry and research, focusing on its role in hydrogen storage.
  • Calcium hydride plays a crucial role in both industrial applications and research. One of its main uses is in hydrogen storage systems where it can release hydrogen gas upon contact with water. This makes it a potential candidate for fuel cells and energy storage technologies. Additionally, its properties as a drying agent help maintain dry conditions for sensitive chemicals during various processes, enhancing efficiency in chemical manufacturing.
• Evaluate the significance of calcium hydride in the context of alkaline earth metals' reactivity and compare it with other compounds formed by these metals.
  • Calcium hydride exemplifies the reactivity of alkaline earth metals when combined with nonmetals like hydrogen. This reactivity is characterized by the formation of ionic compounds that are typically more stable than their counterparts from alkali metals. Comparing calcium hydride to other alkaline earth metal hydrides reveals that while they all produce hydrogen gas upon reaction with water, they differ in their thermal stability and ease of formation. Understanding these differences helps highlight the unique properties and potential applications of calcium hydride relative to other compounds within the group.

Related terms

Hydride: A compound in which hydrogen is combined with another element, often forming ionic or covalent bonds.

Alkaline Earth Metals:

The group of metals in Group 2 of the periodic table, including beryllium, magnesium, calcium, strontium, barium, and radium, known for their reactivity and formation of oxides and hydroxides.

Calcium:

A chemical element with the symbol Ca and atomic number 20, it is a silvery-white metal that is an essential nutrient for living organisms and has various industrial uses.