counting atoms chapter 9. mole?? moles of particles in one mole of a substance, there are 6 x 10 23...

Counting AtomsChapter 9

MOLE??

Moles of Particles

In one mole of a substance, there are 6 x 1023 particles

Calculating the number of moles from the number of particles

TB P147

1. Calculate the number of moles of particles in a. 2.4 x 1023 atoms of hydrogen, Hb. 4.2 x 1024 molecules of carbon dioxide, CO2

c. 3 x 1022 copper ions, Cu2+

Number of moles = Number of particles

6 × 1023

Calculating the number of moles from the number of particles

TB P147

2. Calculate the number of particles in a. 3 moles of carbon atoms, Cb. 0.75 moles of ammonia molecules, NH3

c. 25 moles of sodium chloride, NaCl

Extension Question! How many atoms are there in 0.75 moles of

ammonia molecules?

Number of moles = Number of particles

6 × 1023

Molar MassThe mass of one mole of any substance is

called the molar mass.

The molar mass is the relative atomic mass of the element in grams.

For Substances Consisting of Atoms

The molar mass is the relative molecular mass of the substance in grams.

For Substances Consisting of Molecules

The molar mass is the relative formula mass of the substance in grams.

For Substances Consisting of Ions

Calculating the number of moles from the molar massNumber of moles =

Mass (in g)

Molar mass (in g)

TB P150

1. (a) How many moles of atoms are contained in 32 g of oxygen atoms?

4. (c) Calculate the mass of 4 mol of oxygen molecules, O2?