One Mole of Water and Salt

In the picture

1. 1A heap of pale crystals on a balance pan: a macroscopic sample that can be weighed in grams.
2. 2A glass beaker of water: a measured liquid sample that can be poured.
3. 3An enlarged two-sphere group: one formula unit of the crystal, made of two joined ions.
4. 4An enlarged three-sphere group: one water molecule, made of three joined atoms.

Examples

• A dozen eggs counts 12 eggs; a mole counts 6.022 × 10²³ particles.
• 18 g of water, about a tablespoon, contains about one mole of water molecules.

Quiz: One Mole of Water and Salt (Age 15)

1. 1

   What kind of unit is a mole most like?

   • A unit of volume, like a litre
   • A unit of mass, like a gram
   • A counting unit, like a dozen
2. 2

   How many particles are in one mole?

   • 6.022 × 10²³ litres
   • 6.022 × 10²³ particles
   • 6.022 × 10²³ grams
3. 3

   What does the mole connect for a sample?

   • Its temperature or pressure to its number of atoms, ions, or molecules
   • Its mass or volume to its number of chemical elements
   • Its mass or volume to its number of atoms, ions, or molecules

The answers, each with its explanation, are in the app. This lesson has left the free week, so its quiz is part of the subscription.