Interconversions and Stoichiometry But First: http://www.youtube.com/watch?v=zGM-wSKFBpo http://www.youtube.com/watch?v=ssaUusY6hWM&NR=1

Conversions So far, we have learned to convert between: Moles Particles (molecules, formula units, atoms) Mass (g) Volume (L) Conversions

Interconversions We have also looked at converting: Between moles of reactants and products (from a balanced chemical equation) Between molecules of reactants and products Between volumes of reactants and products (if all are gases) Interconversions

Turns out, we can relate the reactants of a chemical reaction to the products by mass as well! Law of the Conservation of Mass: During a chemical reaction, the total mass of the reactants is always equal to the total mass of the products. Mass Relationship

Nitrogen gas reacts with oxygen gas to yield ammonia gas N2(g) + 3H2(g)  2NH3(g) + 1 molecule N2 1 mol N2(q) 22.4 L N2(g) 28 g N2(g) 3 molecules H2(g) 3 mol H2(g) 67.2 L H2(g) 6 g H2(g) 2 molecule NH3(g) 2 mol NH3(g) 44.8 L NH3(g) 34 g NH3(g) + = Interconversions

Nitrogen gas reacts with oxygen gas to produce nitrogen monoxide Write the balanced chemical equation and describe the reaction in terms of: A) moles B) molecules C) volume D) mass Try it

The study of the relative quantities of reactants and products in chemical reactions Gravimetric stoichiometry: analysis involving mass Gas stoichiometry: analysis involving volume of gases Stoichiometry

Stoichiometry Need the double Y diagram Essentially the same type of conversions we have been doing, but now we are converting between different compounds Need to use the mole ratio! Mole Ratio Stoichiometry

Carbon dioxide reacts with lithium hydroxide according to the following equation: CO2(g) + 2LiOH(s)  Li2CO3(s) + H2O(g) What mass of LiOH is required to react with 1000g of CO2? Mole Ratio Example

Example: Cont. CO2(g) + 2LiOH(s)  Li2CO3(s) + H2O(g) Given: 1000 g CO2 Therefore, 1090g of LiOH would be required to react with 1000g of CO2. Example: Cont.

General Steps 1. Write the balanced chemical equation. 2. If you are given the mass, volume, or number of particles of a substance convert it to moles. 3. Use the mole ratio to calculate the number of moles of the required substance from the moles of the known substance. 4. If required, convert the moles of the required substance to mass (g), volume (L) or number of particles. General Steps