150 likes | 165 Views
Chapter 12 Stoichiometry part 1. Stoichiometry. The study of quantitative relationships between amounts of reactants used and products formed by a chemical reaction. Stoichiometry. Calculations of quantities in chemical reactions
E N D
Stoichiometry The study of quantitative relationships between amounts of reactants used and products formed by a chemical reaction
Stoichiometry • Calculations of quantities in chemical reactions • This means using balanced equations to calculate quantities of chemicals used in a chemical reaction
Law of Conservation of Mass • Matter is neither created nor destroyed in a chemical reaction • Chemical bonds in reactants break and new chemical bonds form to produce products • Mass of reactants equals the mass of the products
A chemical equation is like a recipe; it shows you how much of each “ingredient” is used and how much product you will have in the end.
The heart of stoichiometry is using a balanced chemical equation as a conversion factor for dimensional analysis.
N2 + 3H2 2NH3 • How many molecules of N2 are there? • How many molecules of H2 are there? • How many molecules of NH3 are there? So one molecule of N2 will react with 3 molecules of H2 to form 2 molecules of NH3. You could also say that one mole of N2 will react with 3 moles of H2 to form 2 moles of NH3.
This equation tells the proportions of N2, H2, and ammonia • The coefficients are in a 1:3:2 ratio • The ratio could mean molecules or moles of each
Review 6.02 x 1023 particles 1 mole molar mass 1N2(g) + 3H2(g) 2NH3(g) 1 mole 3 moles 2 moles 28.00g 3(2.02)=6.06g 2(14.00+3.03)=34.06g
Steps to solve every problem: • Write a balanced equation. • Put what you have over 1. • Convert into moles. • Compare using the equation. • Convert into the unit the question asks for.
Mole to Mass conversion: Mole to Mole conversions: Conversion factor (as with any conversion factor, units must cancel) Moles of known x moles of unknown = moles unknown Moles of known The mole ratios of the balanced equation is known, and you’re given a quantity in moles, now find the mass of another product or reactant.
Burning of propane gas:C3H8(g) + 5O2(g) 3CO2(g) + 4H2O(g) How much oxygen is needed to produce 18 mol of CO2?
Zn + HCl ZnCl2 + H2 • For the above reaction, how many moles of zinc chloride can be produced with 0.27 moles of zinc? • For the above reaction, how many moles of zinc will react with 1.39 moles of hydrochloric acid?
Fe + O2 Fe2O3 • How many grams of iron (III) oxide can be produced with 17.2g Fe? • How many molecules of O2 are needed to produce 3.92g Fe2O3?
Mass to Mass conversion: Again, the mole ratios of the balanced equation is known and you’re given a quantity in grams, now find the mass of another product or reactant. C3H8(g) + 5O2(g) 3CO2(g) + 4H2O(g) 67.02g propane would produce ? grams of water vapor?