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Questions and Answers
What is the relationship between the molar mass and the molecular mass of a compound?
If a scientist has 10.00 g of carbon, how many moles of carbon does this represent?
What is the mass of 0.905 moles of sodium chloride (NaCl)?
How many water molecules are in 3.26 g of water?
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What is the empirical formula of a compound that is 30.45 percent nitrogen and 69.55 percent oxygen by mass?
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What is the mass of 7.92 × 10¹⁹ molecules of carbon dioxide (CO₂)?
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How is the molar mass of a compound calculated from its empirical formula?
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What is the molar mass of oxygen used in calculating the empirical formula?
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What is the value of Avogadro's number?
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How many grams are in one mole of carbon-12?
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If a body contains 30 moles of calcium, how many calcium atoms does it contain?
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What is the molar mass of sodium, in grams per mole?
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How many moles are present in a sample containing 1.00 × 10^20 calcium atoms?
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Which of the following correctly describes the relationship between atomic mass and molar mass?
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What is the number of objects in a mole?
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The atomic mass of calcium is approximately how many amu?
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Study Notes
The Mole
- A mole is a unit of measurement that counts the number of particles in a substance.
- A mole is defined as the number of atoms in exactly 12 g of carbon-12.
- Avogadro's number (NA) represents the number of atoms in a mole, which is 6.0221418 × 10^23.
Molar Mass
- Molar mass (M) refers to the mass in grams of one mole of a substance. It is measured in g/mol.
- The molar mass of carbon-12 is exactly 12 g/mol.
- An element's molar mass in grams is numerically equal to its atomic mass in atomic mass units (amu).
- The molar mass of a compound is numerically equal to its molecular or formula mass in amu.
Interconverting Mass, Moles, and Numbers of Particles
- You can calculate the number of moles of a substance by dividing the mass by its molar mass.
- You can calculate the mass of a substance by multiplying the number of moles by its molar mass.
- You can calculate the number of particles in a substance by multiplying the number of moles by Avogadro's number.
Empirical Formula from Percent Composition
- The empirical formula represents the simplest whole-number ratio of atoms in a compound.
- The percent composition of a compound can be used to determine its empirical formula.
- To determine the empirical formula, assume a 100-g sample and convert the mass percentages of each element to moles.
- The mole ratios of the elements will then give you the empirical formula.
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Description
Test your understanding of moles and molar mass with this interactive quiz. Explore concepts like Avogadro's number and how to interconvert mass, moles, and the number of particles in a substance. Perfect for students learning foundational chemistry principles.
