The Mole and Chemical Composition

Mole

6.022x10 23 /mole◦ Can be: ions, molecules, atoms, formula units

Practice Page 2281. How many ions are there in 0.187 mol of Na+ ions?

Practice page 2284. How many formula units are there in 5.9 mol of NaOH?

Page 229: Determine the number of moles of each specified atom or ion in the give samples of the following compounds.

a. O atoms in 3.161X1021molecules of CO2

The mass in grams of one mole of substance Example page 231 practice2) 3.01X 1023 formula units of NaCl (molar mass of NaCl=58.44 g/mol)

Na molar mass:

Cl molar mass:

3) 3.990x1025 molecules of CH4 (molar mss of CH4=16.05 g/mol)

1. Find the number of atoms in 237 g Cu (molar mass of Cu= 65.55 g/mol)

Weighted average of masses of all naturally occurring isotopes of an element

Example page 236 practice 2 Calculate the average atomic mass of oxygen. Its compositions is 99.76%

of atoms with a mass of 15.99 amu, 0.038% with a mass of 17.00 amu, and 0.20% with a mass 18.00 amu.

Find the molar mass for the compound B) CaHPO4

Write the formula and then find the molar massF) tin (II) chloride

The Percentage by mass of each element in a compound

Example: H2O

Find the % composition of a compound which contains 16.56g C, 26.22g F, and 4.14 g H

Lowest whole number ratio of elements in a compound.

1. Percent to mass2. Mass to moles3. Divide each mole value by the smallest

number of moles calculated4. Multiply (or round) till whole

Example: A chemical analysis of a liquid shows that there is 60.0% C, 13.4% H, and 26.6% O by mass. Calculate the empirical formula of the substance.

Whole-number multiples of empirical formulas.

Calculate the molecular formula of the compound whose molar mass is 60.0 g/mol and empirical formula is CH4N

Determine the molecular formula for a compound for a compound that has a molar mass of 34g and is 94.1% oxygen and 5.9% hydrogen.