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Water and Its Properties in General Biology

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  • What makes water a polar molecule?

    Water has two highly polar covalent bonds arranged in a V shape, with a partially negative oxygen atom and partially positive hydrogen atoms.

  • How does water's polarity relate to hydrogen bonding?

    Water's polarity allows it to form hydrogen bonds where the partially positive hydrogen atoms attract the partially negative oxygen atoms of neighboring molecules.

  • What is cohesion in water?

    Cohesion is the attraction between water molecules due to hydrogen bonding, causing them to stick together.

  • What causes water's surface tension?

    Surface tension arises from cohesion among surface water molecules, making it difficult to break the surface of water.

  • What is adhesion in water?

    Adhesion is water molecules sticking to other polar or charged substances, aiding in transport in plants.

  • How does water's high specific heat affect temperature regulation?

    Water absorbs or releases large amounts of heat with little temperature change due to hydrogen bonds breaking and forming, stabilizing environmental temperatures.

  • What is heat of vaporization in water?

    Heat of vaporization is the heat required to convert 1 g of water from liquid to gas, which is high due to hydrogen bonds needing to be broken.

  • How does evaporative cooling work in water?

    When water evaporates, molecules with the highest kinetic energy leave, cooling the remaining liquid's surface.

  • Why does ice float on liquid water?

    Ice is less dense because hydrogen bonds form a stable, spacious crystal lattice, spacing molecules farther apart than in liquid water.

  • Define solute, solvent, and solution.

    A solute is the substance dissolved, the solvent is the dissolving agent, and the solution is the uniform mixture of both.

  • What does 'like dissolves like' mean in water's solvent properties?

    Polar and ionic substances dissolve in water (polar solvent), while nonpolar substances do not.

  • What is a mole in chemistry?

    A mole is 6.02 x 1023 particles of a substance, representing a specific number of atoms or molecules.

  • Difference between molecular mass and molar mass?

    Molecular mass is the sum of atomic masses in a molecule (Daltons), molar mass is the mass of one mole of molecules in grams.

  • How is molarity calculated?

    Molarity = moles of solute divided by liters of solution; it measures solute concentration.

  • What defines hydrophilic and hydrophobic molecules?

    Hydrophilic molecules are polar or ionic and interact with water; hydrophobic molecules are nonpolar and do not interact with water.

  • Write the dissociation equation of water.

    2 H\(_2\)O ā‡Œ H\(_3\)O+ + OHā€“

  • How do acids and bases affect [H+] in solution?

    Acids increase [H+] by donating protons; bases decrease [H+] by accepting protons.

  • What is the pH scale and its relation to acidity?

    pH = -log10[H+]; pH < 7 is acidic, pH = 7 neutral, pH > 7 basic.

  • How do buffers maintain pH stability?

    Buffers minimize pH changes by donating H+ when pH rises and accepting H+ when pH drops, often using weak acid-base pairs.

  • Example of a biological buffer system?

    The bicarbonate buffer system: H2CO3 ā‡Œ HCO3ā€“ + H+, which regulates blood pH.