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Chapter 2 lecture 3

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Termini in questo insieme (23)

  • What type of bond exists between oxygen and hydrogen within a water molecule?
    A polar covalent bond exists between oxygen and hydrogen within a water molecule.
  • What type of bond links water molecules together?
    Hydrogen bonds link water molecules together.
  • Define cohesion in the context of water molecules.
    Cohesion is the linking together of like molecules, often by hydrogen bonds.
  • What is surface tension in water?
    Surface tension is a measure of how difficult it is to stretch or break the surface of a liquid.
  • Define adhesion related to water molecules.
    Adhesion is the clinging of one substance to another, often by hydrogen bonds.
  • What is thermal energy in relation to atoms and molecules?
    Thermal energy is the total energy associated with the random movement of atoms and molecules.
  • How is temperature defined in terms of molecular energy?
    Temperature is the average energy of the molecules of a body of matter, regardless of volume.
  • Explain why water requires a lot of energy to change temperature.
    Water requires a lot of energy to change temperature because heat is used to disrupt hydrogen bonds before speeding up molecules.
  • What is evaporative cooling?
    Evaporative cooling occurs when the hottest molecules escape from a liquid into gas, leaving behind a cooler liquid.
  • Why does ice float on liquid water?
    Ice floats because hydrogen bonds in ice are stable and form a less dense structure than liquid water, where bonds constantly break and reform.
  • What would happen if ice sank in bodies of water?
    If ice sank, bodies of water would freeze solid, disrupting ecosystems.
  • Define a solution in chemistry.
    A solution is a liquid that is a homogeneous mixture of two or more substances.
  • What is the solvent in saltwater?
    In saltwater, water is the solvent.
  • What is the solute in saltwater?
    In saltwater, salt (NaCl) is the solute.
  • Define hydrophilic substances.
    Hydrophilic substances have an affinity for water and are typically ionic or polar.
  • Define hydrophobic substances.
    Hydrophobic substances repel water and are typically nonionic and nonpolar.
  • What is an acid in terms of H+ concentration?
    An acid is a substance that increases the concentration of H+ ions in water.
  • What is a base in terms of H+ concentration?
    A base is a substance that reduces the concentration of H+ ions in water.
  • What is the role of buffers in aqueous solutions?
    Buffers minimize changes in concentrations of H+ and OH- ions, maintaining pH stability.
  • What does a pH of 7 represent?
    A pH of 7 is neutral, meaning equal concentrations of H+ and OH- ions.
  • How much more acidic is a solution with pH 5 compared to pH 7?
    A solution with pH 5 is 100 times more acidic than a solution with pH 7, due to the logarithmic scale.
  • Is a solution with pH 5 acidic or basic?
    A solution with pH 5 is acidic.
  • Does a solution with pH 11 or pH 13 have more H+ ions?
    A solution with pH 11 has more H+ ions than one with pH 13, since higher pH means fewer H+ ions.