Chemistry: Understanding the Mole
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Questions and Answers

What is the term for the mass of one mole of a substance, expressed in grams per mole?

  • Atomic mass
  • Molar mass (correct)
  • Molecular mass
  • Formula mass

    • How many particles are there in one mole of any substance?

  • 1.0 x 10^24
  • 1.0 x 10^23
  • 6.02 x 10^23 (correct)
  • 12.04 x 10^23

    • Which of these elements exist as diatomic molecules in nature?

  • Phosphorus (P)
  • Chlorine (Cl) (correct)
  • Sodium (Na)
  • Sulfur (S)

    • If you have 2 moles of water (H₂O), how many hydrogen atoms do you have?

    <p>24.08 x 10^23 (D)</p> Signup and view all the answers

    What type of mass is used for ionic compounds in the context of molar masses?

    <p>Formula mass (C)</p> Signup and view all the answers

    If you have a sample of 127.0 grams of copper, approximately how many moles of copper are present? (molar mass of copper is 63.5 g/mol)

    <p>2 moles (B)</p> Signup and view all the answers

    How many total atoms are present in a single molecule of sucrose (C₁₂H₂₂O₁₁)?

    <p>45 (C)</p> Signup and view all the answers

    If you have 150.0g of H2O, and know its molar mass to be 18.0g/mol, what are the approximate number of moles of H2O?

    <p>8.33 (C)</p> Signup and view all the answers

    A compound is found to contain 0.900 g of calcium and 1.600 g of chlorine. What is its empirical formula?

    <p>CaCl₂ (C)</p> Signup and view all the answers

    An iron oxide is found to be 78% iron. What is its empirical formula?

    <p>FeO (A)</p> Signup and view all the answers

    How many grams of $C_{12}H_{22}O_{11}$ are present in 1 mole?

    <p>342.0 g (C)</p> Signup and view all the answers

    For a compound with the empirical formula CH and a molecular mass of 78 g/mol, what is its molecular formula?

    <p>C₆H₆ (C)</p> Signup and view all the answers

    A compound contains 42.5 g of palladium and 0.80 g of hydrogen. The molar mass of the compound is 216.8 g/mol. Determine the molecular formula.

    <p>Pd₂H₄ (D)</p> Signup and view all the answers

    According to Avogadro's Law, what happens to the volume of a gas if the amount of gas increases at constant temperature and pressure?

    <p>The volume increases (D)</p> Signup and view all the answers

    What is the volume occupied by one mole of any gas at Standard Temperature and Pressure (STP)?

    <p>22.4 L (B)</p> Signup and view all the answers

    What is the percent concentration by mass of a solution containing 25 g of solute in 225 g of solution?

    <p>11.1% (A)</p> Signup and view all the answers

    Which of the following variables is NOT directly used in the Ideal Gas Law equation?

    <p>Density (C)</p> Signup and view all the answers

    What is the molarity of a solution when 37 g of NaCl are dissolved in 150 mL of solution?

    <p>4.2 M (A)</p> Signup and view all the answers

    Which of the following statements regarding the molar volume of gases is correct?

    <p>All gases have the same molar volume at the same temperature and pressure. (A)</p> Signup and view all the answers

    How many moles of HCl are present in 145 mL of a 2.25 M HCl solution?

    <p>0.326 mol (D)</p> Signup and view all the answers

    What is the molality of a solution that contains 8.50 g of calcium nitrate in 125 g of water?

    <p>0.41 m (C)</p> Signup and view all the answers

    Which of the following correctly describes the relationship between the number of gas particles and pressure inside a container at a constant temperature and volume?

    <p>More gas, more collisions and more pressure. (A)</p> Signup and view all the answers

    1 molecule of $C_{12}H_{22}O_{11}$ contains how many oxygen atoms?

    <p>11 (A)</p> Signup and view all the answers

    What does the 'n' represent in the Ideal Gas Law equation, $PV = nRT$?

    <p>Number of moles (B)</p> Signup and view all the answers

    Flashcards

    Mole

    A unit that represents 6.02 x 10^23 particles.

    Mole

    A unit representing 6.02x10²³ particles of a substance.

    Molar Mass

    The mass of one mole of a substance in grams per mole (g/mol).

    1 mole of C12H22O11

    342.0 grams of sucrose (C12H22O11).

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    Molar Volume at STP

    1 mole of gas occupies 22.4 L at STP (273 K & 1 atm).

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    Formula Unit

    The lowest whole-number ratio of ions in an ionic compound.

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    Avogadro’s Law

    Equal volumes of gases contain equal particles at same conditions.

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    Atomic Mass Unit (amu)

    A unit of mass used to express atomic and molecular weights (1 amu = 1/12 mass of C-12).

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    Conversions: Moles to Grams

    To find grams from moles, multiply moles by molar mass (g/mol).

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    Ideal Gas Law

    PV = nRT, describes gas behavior under certain conditions.

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    Conversions: Moles to Atoms

    To find atoms from moles, multiply moles by Avogadro's number (6.02 x 10²³).

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    Empirical Formula

    The smallest whole-number ratio of atoms in a compound.

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    Gas pressure relation

    More gas leads to more collisions and higher pressure.

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    1 Mole = Mass (g) from PT

    The mass in grams of one mole of a substance is found on the periodic table.

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    Calculating gas volume

    Use ideal gas law to find volume of gas under conditions.

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    Molecular Mass

    The sum of the atomic masses of all atoms in a molecule, measured in amu or g/mol.

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    Molecular Formula

    Indicates the actual number of atoms of each element in a molecule of a compound.

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    Molarity (M)

    Concentration measured as moles of solute per liter of solution.

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    Molality (m)

    Concentration measured as moles of solute per mass of solvent in kg.

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    Percent Concentration by Mass

    Calculated as (mass of solute/mass of solution) x 100%.

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    Solute

    The substance dissolved in a solution.

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    Solution

    A homogeneous mixture of two or more substances.

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    Study Notes

    The Mole

    • A mole is a unit of measurement in chemistry, representing 6.02 x 1023 particles (atoms, formula units, or molecules).
    • One mole of a substance equals its mass in grams, as determined from the periodic table (PT).

    Getting to Know the Terms

    • Microscopic Mass: Atomic mass (amu) for atoms, molecular mass (amu) for molecules, and formula mass (amu) for ionic compounds.
    • Macroscopic Mass: Molar mass (g/mol) for elements, molecular compounds, and ionic compounds.
    • Key elements existing as molecules in nature are H2, O2, F2, Br2, I2, N2, Cl2, S8, and P4

    Mole Relationships

    • 1 mole = 6.02 x 1023 particles (atoms, formula units, or molecules).
    • 1 mole = mass (grams) of the substance from the PT.
    • 1 molecule = number of atoms.
    • 1 formula unit = number of ions or atoms.

    Mole Conversions

    • Calculations between moles, mass, and numbers of particles require the use of factor labels.
    • Conversions must account for the number of atoms/ions in a molecule/formula unit.

    Avogadro's Law

    • Equal volumes of gases at the same temperature and pressure contain an equal number of particles.
    • One mole of any gas occupies 22.4 L at standard temperature and pressure (STP).

    Molar Mass

    • The molar mass of a substance is the mass of one mole of that substance, measured in grams.
    • Molar mass does not affect the volume of a gas at constant pressure, temperature and quantity of moles.

    Ideal Gas Law

    • Ideal gas law describes the relationship between pressure, volume, number of moles, and temperature of a gas.
    • The ideal gas law equation is PV = nRT.

    Empirical Formulas

    • Empirical formulas represent the smallest whole-number ratio of atoms in a compound.
    • Determination of these formulas involves using experimental data, typically mass percentages.

    Molecular Formulas

    • Molecular formulas show the actual number of atoms of each element in a molecule.
    • Molecular formula is a multiple of the empirical formula.
    • The molecular formula can be calculated given the empirical formula and molar mass.

    Concentration

    • Percent concentration by mass = (solute/solution) x 100%
    • Molarity (M) = moles of solute / liters of solution (mol/L)
    • Molality (m) = moles of solute / mass of solvent (kg) (mol/kg)

    Molarity or Concentration Calculations and Problems

    • Standard solutions can be prepared via exact calculation and standardized instruments.
    • Calculations of molarity and dilution require the use of proper formulas and unit conversions.

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    Related Documents

    Mole Chemistry 6.0 PDF

    Description

    This quiz explores the concept of the mole in chemistry, a fundamental unit of measurement representing 6.02 x 1023 particles. It covers topics such as microscopic and macroscopic mass, mole relationships, and conversions. Test your understanding of these essential principles in this interactive assessment.

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