Chapter 10 Moles and Molar Calculations

Number of Particles in a Mole Avogadro’s Number 1 mole = 6.02 X representative particles. (atom, molecule, etc.)

What is a mole? - It is just a word that means a number. - Just like a dozen - A score - A gross - A furlong x 10 23

Mass of a Mole of an Element Gram Atomic masses (find them on the periodic table for single elements). This is the mass of one mole of that element. - You can change the label from amu to grams because there are 6.02 x amu in a gram

How to find gram atomic masses Also called formula masses/weight, molecular masses/weight C: 2 x g = g H: 6 x g = g O: 6 x g = g g g g = g Ex. C 2 O 6 H 6

Mole-Mass and Mole-Volume Relationships Molar mass: Mass of one mole of a substance - This means it is not the mass of one molecule it is the mass of 6.02 x molecules.

% Composition and Chemical Formulas % composition: the relative amounts of each element in a compound. To find the percent composition for the elements in a chemical formula you would: 1. Find the molecular mass of each element in the compound 2. Add all of the masses to get the molecular mass. 3. Divide the mass of each element by the molar mass of the molecule and multiply by 100%

Mole Road Map Page 303 Posterboard example

Volume of a Mole of Gas Volume of a gas is measured at STP (standard temperature and pressure) - STP = 0 Celcius, 1 atmosphere (101.3 kPa) - At STP: 1 mole gas = 22.4 liters

Calculating Empirical Formulas Empirical Formula: Lowest whole number ratio of the atoms of elements in the compound Worksheet will be given on how to calculate empirical formulas from %.

Calculating Molecular Masses Can calculate molecular formulas from the given empirical formula. Ex: HO = H 2 O 2 Some empirical and molecular formulas are the same.