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Water Chemistry and Properties - General Chemistry

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Terms in this set (20)

  • Who identified the chemical composition of water and when?
    Henry Cavendish identified water's composition as two hydrogen atoms and one oxygen atom in 1784.
  • What is the chemical formula of water?
    The chemical formula of water is \(H_2O\), consisting of two hydrogen atoms bonded to one oxygen atom.
  • What type of bond holds the hydrogen and oxygen atoms together in water?
    Hydrogen and oxygen atoms in water are held together by covalent bonds.
  • What is the balanced chemical equation for the formation of water from hydrogen and oxygen gases?
    The reaction is \(2H_2 + O_2 \rightarrow 2H_2O\).
  • What is the bond energy of the H-H bond in hydrogen gas and how is it used in the reaction?
    The H-H bond energy is 436 kJ/mol; for two H2 molecules, total bond energy broken is 872 kJ/mol.
  • What is the bond energy of the O=O double bond in oxygen gas?
    The O=O double bond energy is 498 kJ/mol.
  • How is the enthalpy change (ΔH) calculated for the water formation reaction?
    ΔH = total bond energy broken - total bond energy formed; here, ΔH = 1,370 kJ/mol - 1,856 kJ/mol = -436 kJ/mol.
  • What unique intermolecular force does water form and why is it important?
    Water forms hydrogen bonds when hydrogen is bonded to oxygen, nitrogen, or fluorine, explaining many unique properties.
  • Why does a water molecule have a bent shape?
    Water's bent shape is due to oxygen's higher electronegativity pulling electron density and two lone pairs repelling hydrogen atoms.
  • What theory explains the bent shape of water molecules?
    The Valence Shell Electron Pair Repulsion (VSEPR) theory explains the bent shape due to electron pair repulsion.
  • What would happen if water had a linear shape instead of bent?
    If linear, water would be non-polar because bond dipoles would cancel, affecting its solvent properties and life-supporting abilities.
  • What are the boiling and melting points of water?
    Water boils at 100°C (212°F) and melts at 0°C (32°F).
  • Why is water called the universal solvent?
    Water dissolves many substances more easily than other liquids due to its polarity and hydrogen bonding.
  • How is water used in energy production?
    Water generates electricity by driving turbine generators with steam in power plants.
  • What impact did the 2012 drought have on power plants in the US?
    Limited water access slowed power plant operations due to water's role in energy production.
  • Why is water quality important in the medical field?
    Poor water quality can damage medical equipment and cause infections or fevers in patients.
  • What percentage of Earth's surface is covered by water?
    About 71% of Earth's surface is covered by water.
  • What percentage of Earth's water is found in lakes and oceans?
    Approximately 97.5% of Earth's water is in lakes and oceans.
  • What is the water cycle?
    The water cycle involves evaporation from oceans, precipitation, glacier formation, and groundwater replenishment.
  • Why is it important that ice floats on water?
    Floating ice insulates water below, protecting aquatic life by preventing entire bodies of water from freezing solid.