Mole-Mass Relationship

The Mole Review What is a mole? How do scientists use the concept of the mole? Who was the first person to come up with the idea of the mole?

Molar Mass The atomic mass of an element expressed in grams is the mass of 1 mole of that element. This is known as the element’s molar mass (the mass of 1 mole) How could we find the molar mass of a compound ?

Finding Molar Mass of Compound Step 1: Obtain chemical formula Step 2: Add up all individual molar masses Step 3: add unit (grams per mole)

Sample Problems in Molar Mass The decomposition of hydrogen peroxide (H 2 O 2 ) provides sufficient energy to launch a rocket. What is the molar mass of hydrogen peroxide? Find the molar mass of PCl 3. What is the mass of 1 mol of sodium hydrogen carbonate?

Mole-Mass relationship We can use the molar mass of a substance as a conversion factor between moles and mass of any substance. Review: What is a conversion factor?

Example The molar mass of NaCl is 58 g/mol So the mass of 3 mol of NaCl can be found in the following way: 3 mol NaCl X 58 g = 176 g 1 mol

Sample Problems The aluminum Satellite dishes are resistant to corrosion because the aluminum reacts with oxygen in the air to form a coating of aluminum oxide. This tough, resistant coating prevents any further corrosion. What is the mass of 9.45 mol of aluminum oxide?

Sample Problems Find the mass, in grams, of mol of C 20 H 42. Calculate the mass, in grams, of 2.5 mol of iron (III) hydroxide.

Mole-Particle Relationship We can convert between moles of a compound/substance and the number of particles in that substance. By Particles we mean… – Atoms – Molecules/compounds

Sample Problems Find the number of molecules in a 75 g sample of dinitrogen trioxide. Find the number of atoms of gold in 2 mol of gold.