The Mole Concept

Front

What is a mole in chemistry?

Back

A mole is a large number used to count particles, specifically 6.022 x 10^23 particles.

Front

How do you calculate the mass of a substance in moles?

Back

Mass (g) = Moles (mol) x Molar Mass (g/mol).

Front

What is the molar mass of oxygen gas (O2)?

Back

The molar mass of O2 is 32 g/mol.

Front

Calculate the mass of 2.50 mol of oxygen gas (O2).

Back

80 g.

Front

What is the molar mass of water (H2O)?

Back

The molar mass of H2O is 18 g/mol.

Front

Calculate the mass of 1.5 mol of water (H2O).

Back

27 g.

Front

What is percent composition?

Back

Percent composition is the percentage by mass of each element in a compound.

Front

What is the percent composition of hydrogen in water (H2O)?

Back

11.2%.

Front

What is an empirical formula?

Back

An empirical formula is the simplest whole-number ratio of elements in a compound.

Front

Given 72.2% magnesium (Mg) and 27.8% nitrogen (N) by mass, what is the empirical formula?

Back

Mg3N2.