(a) Write 'true' or 'false' for each statement. (b) A mole of water has a mass of 18.0 g.

Key Concepts

Mole Concept

The mole is a fundamental unit in chemistry that quantifies the amount of substance. One mole contains approximately 6.022 x 10^23 entities, such as atoms or molecules. This concept allows chemists to convert between the mass of a substance and the number of particles it contains, facilitating stoichiometric calculations.

Molar Mass

Molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). For water (H2O), the molar mass is calculated by summing the atomic masses of its constituent elements: hydrogen (1.01 g/mol) and oxygen (16.00 g/mol), resulting in a total of approximately 18.0 g/mol. This value is crucial for converting between mass and moles.

Density and Mass Relationships

Understanding the relationship between mass, volume, and density is essential in chemistry. Density is defined as mass per unit volume (d = m/V). For water, knowing its density (1 g/cm³) helps confirm that a mole of water, which has a mass of 18.0 g, occupies a volume of about 18.0 cm³, reinforcing the connection between these properties.