Chapter 10 The Mole

Chemical Measurements Atomic Mass Units (amu) – The mass of 1 atom – 1 oxygen atom has a mass of 16 amu Formula Mass (amu or fu) – The sum of the masses in a single compound or molecule – The mass of 1 H 2 O molecule is 18 amu or fu

The Mole Avogadro’s Number 6.02 x mole = 6.02 x atoms 1 mole = 6.02 x molecules 1 mole = 6.02 x fu

One Step Conversions Mass – Mols – Divide by the molar mass. – Examples Mols – Mass – Multiply by the molar mass – Examples Particles – Mols – Divide by 6.02 x – Examples Mols – Particles – Multiply by 6.02 x – Examples

Molar Mass The mass in grams of 1 mole of substance. Examples – Cl 2 – NaCl – Pb(NO 3 ) 2

Multistep Conversions Particles – Mass – Divide by 6.02 x – Then multiply by the molar mass – Examples Mass – Particles – Divide by the molar mass – Then multiply by 6.02 x – Examples

Gas Conversions Molar volume = 22.4 L per mol Mol – Volume – Multiply by the molar volume – Examples Volume – Mols – Divide by the molar volume – Examples Volume – Particles or Volume - Mass – Divide by the molar volume and then multiply by 6.02 x particles or by the molar mass. – Examples Particles – Volume or Mass – Volume – Divide by 6.02 x particles or molar mass and then multiply by the molar volume. – Examples

Percentage Composition Molar mass of element/molar mass of compound Examples

Determining Empirical Formulas If given % change it to grams Convert to moles Use smallest mole value to divide by each component Round to the nearest whole number Use that number to put into the formula Example

Determining Molecular Formulas Start by finding the empirical formula Molar mass of compound/empirical formula mass Take that number and multiply it into the empirical formula Examples