Stoichiometry “Calculating Quantities in Reactions”

Balanced Equations Show Proportions The coefficients in a balanced chemical equation represent the numbers of particles for each substance in the reaction. 2H 2 + O 2  2H 2 O For this equation, the coefficients show that _____ molecules of hydrogen react with _____ molecules of oxygen to yield _____ molecules of water.

Amounts in Moles Just as you can interpret these equations in terms of particles, you can interpret them in terms of moles. The coefficients in a balanced equation also represent the moles of each substance. 2C 8 H O 2  16CO H 2 O How many moles of octane react? ______________ How many moles of oxygen react? ______________ How many moles of CO 2 are produced? ______________ How many moles of water are produced? ______________

Mole Ratios in a Rxn Stoichiometry – the proportional relationship between two or more substances during a chemical reaction. You will soon be able to determine how much of a product is formed from a given quantity of reactant. The mole ratio is the key. The coefficients are ratios or conversion factors to convert between reactants and products. These ratios are called MOLE RATIOS

Practice With Mole Ratios Consider the following reaction: Phosphoric Acid neutralizes Barium Hydroxide  ?? What is the molar ratio of acid to base? __________. Base to salt? __________. Acid to salt? __________. Base to acid? __________. Water to acid? __________. Water to base? __________. Base to water? __________.

Making Calculations The mole ratios are in ____________, obviously. You may ONLY convert between reactants and products through MOLES using the mole ratio as a conversion factor. Make a T-Chart and solve just as we have done in the past

Order of Operations Grams of “A”1 mole of “A” Molar mass of “A” (in grams) # of moles of “B” # of moles of “A”1 mole of “B” Molar mass of “B” (in grams) Molar Ratio of “A” to “B” This process enables us to convert from one reactant to another, one reactant to a product, or one product to another using the molar ratios from the balanced chemical equation.

Practice With Stoich How many moles of water can be produced by the combustion of 2.45 moles of propane? Step 1: Write out the balanced reaction. Step 2: Determine the molar ratio or the starting component and the ultimate component. Step 3: Make a chart of relationships and solve.

Practice with Conversions Convert 0.85 moles of oxygen gas to grams of oxygen gas. Convert grams of pentane (C 5 H 12 ) to moles of pentane

Practice with Conversions How many grams of oxygen are required to burn grams of pentane (C 5 H 12 ) to completion?

Stoichiometry Problems ___POCl 3(l) + ___H 2 O (l)  ___H 3 PO 4(l) + ___HCl (g) How many grams of hydrochloric acid will be produced from the consumption of grams of POCl 3 ?

Stoichiometry Problems 1 POCl 3(l) + 3 H 2 O (l)  1 H 3 PO 4(l) + 3 HCl (g) How many grams of hydrochloric acid will be produced from the consumption of grams of POCl 3 ? How many grams of phosphoric acid will be produced with this quantity of POCl 3 ?

More Practice What volume of H 3 PO 4 forms when 56 mL POCl 3 completely react? (density of POCl 3 = 1.67 g/mL; density of H 3 PO 4 = 1.83 g/mL) 1 POCl 3(l) + 3 H 2 O (l)  1 H 3 PO 4(l) + 3 HCl (g)

Using Molecules How many grams of C 5 H 8 form from 1.89x10 24 molecules C 5 H 12 ?C 5 H 12(l)  C 5 H 8(l) + 2H 2(g)

Get started on your homework packet “Calculating Quantities in Reactions” This will be homework and is due tomorrow