Mole Concept and Molar Masses

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Questions and Answers

What is the value of Avogadro's constant?

6.022 × 10^25

6.022 × 1023 (correct)

6.022 × 10^30

6.022 × 10^20

What is the unit of molar mass?

u mol–1

g mol–1 (correct)

u (unified atomic mass units)

mol u

What is the molar mass of water?

18.02 g mol–1 (correct)

18.03 g mol–1

18.04 g mol–1

18.01 g mol–1

How many particles are present in one mole of a substance?

6.022 × 1023 Signup and view all the answers

What is the mole concept used for?

To count entities at the microscopic level Signup and view all the answers

What is the molar mass of sodium chloride?

58.5 g mol–1 Signup and view all the answers

What is the symbol for the mole unit?

mol Signup and view all the answers

What is the formula mass of a substance in u?

The same as the molar mass in u Signup and view all the answers

What is the unit of volume in the denominator of the unit factor when converting from cm³ to m³?

106 cm Signup and view all the answers

Who is credited with the discovery of the Law of Conservation of Mass?

Antoine Lavoisier Signup and view all the answers

What is the volume of 2 L of milk in m³?

0.002 m³ Signup and view all the answers

What is the significance of Lavoisier's experiments?

He reached the conclusion that matter can neither be created nor destroyed Signup and view all the answers

What is the relationship between 1 L and 1 m³?

1 L = 0.001 m³ Signup and view all the answers

What was the basis for Lavoisier's conclusion about the Law of Conservation of Mass?

Careful measurement of masses of reactants and products Signup and view all the answers

What is the conversion factor from cm to m?

1 cm = 0.001 m Signup and view all the answers

What is the significance of Lavoisier's work?

It formed the basis for several later developments in chemistry Signup and view all the answers

What is the unit of Avogadro's constant?

mol–1 Signup and view all the answers

What is the amount of substance symbolized by?

n Signup and view all the answers

What is the mass of a carbon-12 atom in grams?

1.992648 × 10–23 g Signup and view all the answers

What is the number of atoms in one mole of carbon?

6.0221367 × 10^23 atoms/mol Signup and view all the answers

What is the molar mass of carbon in grams per mole?

12 g/mol Signup and view all the answers

What is the first question to ask when given an unknown compound?

What is its formula? Signup and view all the answers

What is an elementary entity?

Any particle or specified group of particles Signup and view all the answers

What is the significance of the mole concept?

It is used to express the amount of a substance in a given sample Signup and view all the answers

Study Notes

Mole Concept and Molar Masses

The mole (symbol: mol) is the SI unit of amount of substance, introduced as the seventh base quantity for the amount of a substance.
One mole contains exactly 6.02214076 × 10^23 elementary entities, known as the Avogadro number.
The amount of substance (symbol: n) is a measure of the number of specified elementary entities, which can be an atom, molecule, ion, electron, or a specified group of particles.
The mole of a substance always contains the same number of entities, regardless of the substance.

Molar Mass

The mass of one mole of a substance in grams is called its molar mass.
Molar mass in grams is numerically equal to atomic/molecular/formula mass in u.
Examples of molar mass: water (H₂O) = 18.02 g mol⁻¹, sodium chloride (NaCl) = 58.5 g mol⁻¹.

Percentage Composition

The percentage of a particular element present in a compound is often required.
The law of conservation of mass states that matter can neither be created nor destroyed, and this law forms the basis for several later developments in chemistry.

Empirical Formula for Molecular Formula

The law of conservation of mass was put forth by Antoine Lavoisier in 1789.
Lavoisier's law states that in all physical and chemical changes, there is no net change in mass during the process.
This law was formed through careful experimental studies and exact measurements of masses of reactants and products.

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Description

This quiz covers the mole concept, molar masses, and the relationship between moles and atoms/molecules. Test your understanding of these fundamental chemistry concepts.