Transcript Chapter 6
Chapter 6 Chemical Quantities Image source: www.moleday.org Atomic Mass & Formula Mass • Atomic Mass • Formula mass – just what it says it is! • Example: – Atomic mass of carbon: 12.01amu – Formula mass of carbon dioxide • 1 carbon atom = 12.01amu x 1 atom = 12.01 • 2 oxygen atoms = 16.00amu x 2 atoms = 32.00 • Total = 44.01 amu for 1 molecule of CO2 The Mole • An experimentally-defined number that is equal to 6.022 x 1023 particles • Called Avogadro’s number, after physicist Amedeo Avogadro – 600 million trillion particles – Can be atoms, molecules, anything in a distinct unit The Mole Molar Mass • Quantity in grams that equals the atomic mass of the element or compound • For example: What is the molar mass of carbon dioxide? Formula mass = 44.01amu / molecule Molar mass = 44.01g / mole Chemical Equations • Textual representation of a reaction • Definitions: Reactant, Product, Coefficient, State of Matter • To balance: – 1. Write down reactants and products with correct subscripts – 2. Add coefficients so that there are the same number of each atom on both sides of the equation – “Least Common Multiples” Try This! • Iron ores such as Fe2O3 are smelted, by reaction with carbon, to form metallic iron and carbon dioxide. • Can you write and balance the equation? • Can you name the iron ore? Try This! • When propane gas, C3H8, burns in oxygen, it produces water and carbon dioxide. Write and balance the equation. What Does This Mean? 2Fe2O3 + 3C 3CO2 + 4Fe 2H2(g) + O2(g) 2H2O(g) • Coefficients are proportions of moles – 2 moles of iron (III) oxide react with 3 moles of carbon to yield 3 moles of carbon dioxide and 4 moles of iron 2 moles iron (III) oxide 4 moles iron 2 moles iron (III) oxide 3 moles carbon dioxide 3 moles carbon dioxide 3 moles carbon Try This! • Butane, a common fuel in lighters, burns according to the following equation. C4H10 + O2 CO2 + H2O • • Balance the equation How many moles of carbon dioxide can I produce if I burn 4 moles of butane? Mass Calculations Try This! • Write a balanced equation for the following reaction: Aluminum sulfate and sodium hydroxide react to form sodium sulfate and aluminum hydroxide. • • How many grams of sodium hydroxide are needed to form 18.7 grams of sodium sulfate? If I begin with 25.9g of aluminum sulfate, how many grams of aluminum hydroxide will form?