Chapter 7Chemical Quantities

The MoleThe Mole

SI base unit to measure the amount of a substance

1 mole of anything = 6.022 x 1023

representative particles

2. How many molecules are in 2.12 mole of propane(C3H8)?

3. How many moles are there in 3.01 x 1023 forumla units of NaOH?

Ex. molecular formula of H2O

H = 2(1.01) = 2.02 O = 1(16.0) =16.0 18.02 gGram formula mass – mass of one

mole of an ionic compound formula mass of CaCl2

9.45 mole N2O3 76.0 g N2O3

1 mole N2O3

= 718 g N2O3

Find the number of moles in 92.2 g of iron(III) oxide.

22.4 L = 1 mole

22.4 L = 6.022 x 1023 representative particles

Density of a gas is in units of g/L g 22.4 L

Percent Composition

Shows the simplest whole-number ratio of the atoms in a compound

Can be the true formula sometimes

1.Analysis shows a compound to contain 26.56% K, 35.41% Cr, 38.03% O. Find the empirical formula.

Indicates the ratio of the atoms

Shows the actual number of atoms Can be reduced sometimes