Mole Concepts

Avogadro’s Principle

- equal volumes of gases at the same temperature and pressure, contain equal numbers of particles

- molar volume – 1 mole of any gas at STP occupies 22.4 L

STP – standard temperature pressure is:

0.00 ºC

1.0 atm of pressure

1 mole 22.4 L

22.4 L 1 mole

* Conversion factors for relating moles to volume

OR

Molarity (M)

the number of moles of solute dissolved per liter of solution

M = moles of solute

L of solution

Measure mass of solute

(convert it to moles)

Use a volumetric flask to bring it to 1.0 L of solution

Percent Composition

- percent by mass of any element in a compound

mass of element x 100 = percent composition

mass of compound

What is the percent composition of water?

H2O

% H = 2.016 g H X 100 = 11.2 % H

18.016 g H2O

% O = 15.99 g 0 X 100 = 88.8 % O

18.016 g H2O