Ch.10 The Mole

Why do you need to know the formula for a molecule in order to calculate the number of moles of one of the atoms?

• Because the number of each type of atom in a molecule determines how many moles of that atom are present in a mole of the compound.

• The formula helps in identifying the molecular weight of the compound.

• Knowing the formula allows you to determine the color of the compound.

• The formula is necessary to understand the physical state of the compound.

How many moles of H₂O are in 15.2 grams of pure ice?

• 0.84 moles

• 0.94 moles

• 0.76 moles

• 0.68 moles

What would be the volume of 3.5 moles of a gas?

• 70.4 L

• 78.4 L

• 82.4 L

• 75.4 L

Calculate the molar mass of CaCl₂.

• 100.00 g/mol

• 110.98 g/mol

• 120.00 g/mol

• 90.00 g/mol

What does an empirical formula tell you?

• Ratio of atoms.

• Exact number of atoms in a molecule.

• Type of chemical bonds present.

• Molecular weight of the compound.

What is a hydrate?

• A compound that contains water molecules bound in its structure.

• A type of salt that does not contain water.

• A gas that forms when water evaporates.

• A solid that is completely dry and contains no moisture.

Why do we need to do all our comparisons at the same temperature and pressure?

• Because gas volume depends on temperature and pressure.

• Because temperature and pressure have no effect on gas volume.

• Because it simplifies calculations regardless of conditions.

• Because it ensures consistency in measurements.

What is the representative particle for an element?

• Molecule

• Atom

• Compound

• Ion

What does an empirical formula not tell you?

• The actual number of atoms (molecular formula).

• The ratio of different types of atoms.

• The type of atoms present in the compound.

• The overall mass of the compound.

How many atoms of chlorine are present in molecules of Cl₂?

• 1 Cl atom

• 2 Cl atoms

• 3 Cl atoms

• 4 Cl atoms