💏intro to chemistry review

key term - Metal Hydrides

Definition

Metal hydrides are chemical compounds formed by the combination of a metal and hydrogen. These compounds have unique properties and play a significant role in the occurrence, preparation, and various applications of hydrogen as an element.

5 Must Know Facts For Your Next Test

  1. Metal hydrides can be used as a means of hydrogen storage, as they can reversibly release and absorb hydrogen gas.
  2. Ionic hydrides, such as lithium hydride (LiH) and sodium hydride (NaH), are commonly used as reducing agents in organic synthesis.
  3. Covalent hydrides, like diborane (B₂H₆), are highly reactive and are used as reducing agents and fuel components.
  4. Interstitial hydrides, like palladium hydride (PdH₂), exhibit unique physical properties, such as increased electrical resistance and volume expansion.
  5. The stability and reactivity of metal hydrides are influenced by the electronegativity difference between the metal and hydrogen, as well as the size and structure of the metal.

Review Questions

  • Explain the role of metal hydrides in the occurrence and preparation of hydrogen.
    • Metal hydrides play a crucial role in the occurrence and preparation of hydrogen. Certain metal hydrides, such as calcium hydride (CaH₂) and lithium aluminum hydride (LiAlH₄), can be used as sources of hydrogen gas. These compounds can release hydrogen through thermal or chemical decomposition, making them valuable in the production and storage of hydrogen. Additionally, metal hydrides can be used as intermediates in the preparation of other hydrogen-containing compounds, demonstrating their importance in the chemistry of hydrogen.
  • Describe the different types of metal hydrides and their unique properties.
    • Metal hydrides can be classified into three main types: ionic hydrides, covalent hydrides, and interstitial hydrides. Ionic hydrides, such as lithium hydride and sodium hydride, are crystalline solids with high thermal stability and are commonly used as reducing agents. Covalent hydrides, like diborane, are highly reactive and are used as reducing agents and fuel components. Interstitial hydrides, exemplified by palladium hydride, exhibit unique physical properties, including increased electrical resistance and volume expansion, due to the incorporation of hydrogen atoms into the metal lattice. The properties of metal hydrides are influenced by the electronegativity difference between the metal and hydrogen, as well as the size and structure of the metal.
  • Analyze the potential applications of metal hydrides in the context of hydrogen occurrence, preparation, and compounds.
    • Metal hydrides have a wide range of applications in the context of hydrogen occurrence, preparation, and compounds. Their ability to reversibly release and absorb hydrogen gas makes them valuable for hydrogen storage, which is crucial for the development of hydrogen-based energy technologies. Ionic hydrides, like lithium hydride, can be used as reducing agents in organic synthesis, facilitating the preparation of various hydrogen-containing compounds. Covalent hydrides, such as diborane, find use as fuel components and reducing agents. Interstitial hydrides, like palladium hydride, exhibit unique physical properties that can be exploited in applications like hydrogen sensors and fuel cells. The versatility of metal hydrides, combined with their ability to influence the occurrence, preparation, and reactivity of hydrogen, underscores their importance in the chemistry of this element.