Structure 1.4—Counting particles by mass: The mole

What is the SI unit of amount of substance?

• mole

• gram

• liter

• meter

How many elementary entities are in one mole?

• 6.022 x 10^22

• 6.022 x 10^23

• 1.2 x 10^24

• 3.14 x 10^22

What is the Avogadro constant used for?

• The Avogadro constant is used to quantify the number of particles in a mole of a substance.

• To calculate the density of a liquid.

• To determine the speed of light in a vacuum.

• To measure the temperature of a gas.

Define an elementary entity in the context of chemistry.

• An elementary entity is an atom of an element.

• A molecule of a compound.

• A mixture of different elements.

• A subatomic particle like a proton.

How do you convert the amount of substance to the number of particles?

• Number of particles = Amount of substance (in liters) × Avogadro's number

• Number of particles = Amount of substance (in moles) ÷ Avogadro's number

• Number of particles = Amount of substance (in moles) × Avogadro's number (6.022 x 10^23)

• Number of particles = Amount of substance (in grams) × Avogadro's number

What is the relative atomic mass of an element based on?

• The average mass of isotopes weighted by abundance.

• The sum of all isotopes without considering their abundance.

• The total number of protons in the nucleus.

• The mass of the most abundant isotope only.

How is the relative formula mass calculated?

• The relative formula mass is found by subtracting the atomic masses of all atoms in the formula.

• The relative formula mass is determined by multiplying the atomic masses of all atoms in the formula.

• The relative formula mass is calculated by averaging the atomic masses of all atoms in the formula.

• The relative formula mass is calculated by summing the atomic masses of all atoms in the formula.

What are the units for relative atomic mass and relative formula mass?

• Moles

• No units (dimensionless)

• Kilograms

• Grams

Why is carbon-12 used as a reference for atomic mass?

• Carbon-12 has a mass of 10 amu, which is used for calculations.

• Carbon-12 is radioactive and decays over time.

• Carbon-12 is a stable isotope with a defined mass of 12 amu, serving as a standard for atomic mass.

• Carbon-12 is the most abundant element in the universe.

What is the relationship between moles and mass?

• Moles and mass are unrelated concepts.

• Moles are equal to mass in grams.

• Moles and mass are related through the formula: mass = moles × molar mass.

• Mass is calculated by dividing moles by molar mass.