Chemistry: Water and Acids
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Questions and Answers

What is the primary characteristic of water molecules that allows them to create hydrogen bonds between each other?

  • Neutral molecules
  • Ionized molecules
  • Non-polar molecules
  • Polar molecules (correct)
  • Water is a non-polar molecule.

    False

    What is the definition of a strong acid or base?

    A strong acid or base is one that completely dissociates in water.

    A _______________ is a solution of a weak acid and its conjugate base.

    <p>buffer</p> Signup and view all the answers

    Which of the following properties of water is responsible for its high surface tension?

    <p>Polarity of water molecules</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Acid = Proton donor Base = Proton acceptor Strong acid or base = Completely dissociates in water Weak acid or base = Partially dissociates in water</p> Signup and view all the answers

    Water has a low boiling point and melting point.

    <p>False</p> Signup and view all the answers

    Water is a _______________ molecule, meaning it has a slightly positive charge on one end and a slightly negative charge on the other.

    <p>polar</p> Signup and view all the answers

    What is the approximate distance of a covalent bond?

    <p>0.0965 nm</p> Signup and view all the answers

    The Henderson-Hasselbalch equation is used to determine the pH of a buffer solution.

    <p>True</p> Signup and view all the answers

    What is the purpose of a buffer solution?

    <p>To resist a large change in pH of a solution</p> Signup and view all the answers

    The bicarbonate buffer system in the blood involves the equilibrium between __________ and __________.

    <p>HCO3- and H2CO3</p> Signup and view all the answers

    Match the following types of non-covalent interactions with their descriptions:

    <p>Ionic bonds = (+) and (-) molecules Electrostatic interaction = (+) and (-) ions Hydration of Ions in Solution = Interaction between ions and water molecules Hydrogen bonding = Constant breakage and formation of hydrogen bonds in water</p> Signup and view all the answers

    What is the approximate number of hydrogen bonds per water molecule at room temperature?

    <p>2.3</p> Signup and view all the answers

    The Henderson-Hasselbalch equation is only effective when the pH is within 1 unit of the pKa of the acid.

    <p>True</p> Signup and view all the answers

    The ratio of acid to base in a buffer solution is related to the __________ of the acid.

    <p>pKa</p> Signup and view all the answers

    What is the primary characteristic of a homogenous mixture?

    <p>Its composition is uniform throughout</p> Signup and view all the answers

    Metals are poor conductors of heat and electricity.

    <p>False</p> Signup and view all the answers

    What is the smallest stable form of matter in the universe?

    <p>Atoms</p> Signup and view all the answers

    The subatomic particle with a positive charge is the _______________________

    <p>proton</p> Signup and view all the answers

    Match the following groups of elements with their characteristics:

    <p>Metals = Located on the left side of the periodic table, good conductors of heat and electricity Nonmetals = Located on the right side of the periodic table, poor conductors of heat and electricity Metalloids = Located on the border between metals and nonmetals</p> Signup and view all the answers

    What is the characteristic of nonmetals?

    <p>Dull appearance, poor conductors of heat and electricity</p> Signup and view all the answers

    Atoms are composed of only two subatomic particles.

    <p>False</p> Signup and view all the answers

    What is the exception to the general characteristic of metals being shiny solids at room temperature?

    <p>Mercury (Hg) is a liquid at room temperature</p> Signup and view all the answers

    What is the primary function of the phosphate buffer in biological systems?

    <p>To facilitate the phosphorylation of proteins</p> Signup and view all the answers

    The pH of blood is controlled solely by the kidneys.

    <p>False</p> Signup and view all the answers

    What is the term for the tendency of hydrophobic molecules to coalesce in an aqueous environment?

    <p>Hydrophobic interactions</p> Signup and view all the answers

    The pKa value of carboxylic acids is approximately _______.

    <p>6.37</p> Signup and view all the answers

    Match the following biological buffers with their locations:

    <p>Phosphate buffer = Intracellular Hemoglobin = Blood Proteins = Both intracellular and blood</p> Signup and view all the answers

    What type of compounds are capable of forming hydrogen bonds with water?

    <p>All of the above</p> Signup and view all the answers

    What is the term for the process by which the lungs regulate blood pH?

    <p>Respiration</p> Signup and view all the answers

    Water is capable of dissolving ionic compounds, polar compounds, and amphipathic molecules.

    <p>True</p> Signup and view all the answers

    What is the primary factor that determines the location of electrons outside the nucleus?

    <p>Number of electrons</p> Signup and view all the answers

    It is possible to know the speed of an electron simultaneously.

    <p>False</p> Signup and view all the answers

    What is the relationship between the number of protons and electrons in a neutral atom?

    <p>A neutral atom has no net overall charge, and the number of protons is equal to the number of electrons (Z = NUMBER OF PROTONS = NUMBER OF ELECTRONS).</p> Signup and view all the answers

    The mass of an electron is considered _______________ so we ignore it.

    <p>negligible</p> Signup and view all the answers

    Match the following subatomic particles with their properties:

    <p>Proton = Positive charge, mass of 1.0073 Electron = Negative charge, negligible mass Neutron = No charge, mass of 1.0087</p> Signup and view all the answers

    What is the term for atoms of the same element that have a different number of neutrons?

    <p>Isotopes</p> Signup and view all the answers

    What is the mass number (A) of an atom with 17 protons and 18 neutrons?

    <p>35</p> Signup and view all the answers

    The nucleus is the location of most of the atom's mass.

    <p>True</p> Signup and view all the answers

    Study Notes

    Properties of Water

    • Water is a liquid at normal temperature with a high boiling point and melting point.
    • Exhibits high heats of fusion and vaporization, and has a considerable heat capacity.
    • Surface tension is significant, which can be observed when diving into water.
    • Water molecules are polar, creating hydrogen bonds that allow interaction with charged molecules.

    Acids and Bases

    • Acids are proton donors, while bases are proton acceptors.
    • Strong acids and bases dissociate completely in solution; weak acids and bases exist in equilibrium with their conjugates.
    • Buffers maintain pH stability in solutions by absorbing excess acids or bases.

    Buffers

    • Are solutions containing weak acids and their conjugate bases to resist pH changes.
    • Buffer capacity depends on the molar concentration and the ratio of acid to base.
    • Effective within ±1 pH unit of their pKa.

    Hydrogen Bonding in Water

    • Water can form 2.3 hydrogen bonds at 0°C and can form a maximum of 4 hydrogen bonds in ice.
    • Constant breakage and formation of bonds contribute to water’s unique properties, including its high heat of vaporization.

    Henderson-Hasselbalch Equation

    • Formula used to relate pH, pKa, and concentrations of acid and base in buffer systems:
      • ( pH = pKa + \log \left[ \frac{[A^-]}{[HA]} \right] )

    Biological Buffers

    • Key examples include bicarbonate in blood:
      • Bicarbonate (HCO₃⁻) equilibrates with carbonic acid (H₂CO₃) and carbon dioxide (CO₂) to regulate blood pH (approx. 7.4).
    • Phosphate buffers are used intracellularly, with pKa approximately 7.2.

    Water as a Universal Solvent

    • Water dissolves ionic and polar compounds, including amphipathic molecules that form micelles in solution.

    Characteristics of Mixtures

    • Mixtures can be homogeneous (uniform composition) or heterogeneous (varying composition).
    • Subdivided into elements and compounds for pure substances, and also classified into homogenous and heterogeneous mixtures.

    Elements and the Periodic Table

    • Elements divided into metals, nonmetals, and metalloids.
    • Metals are good conductors, shiny at room temperature (except mercury), and typically located on the left side of the periodic table.
    • Nonmetals have dull appearances, are poor conductors, and reside on the right side of the periodic table.

    Atomic Structure

    • Atoms consist of protons (positive charge), neutrons (neutral), and electrons (negative charge).
    • Protons and electrons are charged; neutrons have negligible mass.
    • Atomic number (Z) equals the number of protons and is unique to each element.

    Isotopes

    • Isotopes of an element have the same number of protons but a different number of neutrons.
    • Mass number (A) is the total of protons and neutrons in an atom.

    Nucleus Structure

    • Nucleus contains protons and neutrons and is where most atomic mass is concentrated.

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    Description

    This quiz covers the properties of water, including its ability to form hydrogen bonds, and the definition of strong acids and bases. It also touches on the concept of conjugate bases and the properties of water that contribute to its high surface tension.

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