Intro to Stoichiometry January 28, 2019

Cookies!!! What is required to make chocolate chip cookies (according to the Nestle Toll House recipe)?

Ingredients Sugar Chocolate Chips Br. Sugar Vanilla Eggs Butter Flour Baking soda Salt

Ratios Matter!!!! 0.75 cp Sugar 1 tsp Salt 0.75 cp Br. Sugar 16 oz Chocolate Chips 2 Eggs 1 tsp Vanilla 2.25 cp Flour 1 cp Butter 1 tsp Baking soda

As an equation 0.75 cp Sugar + 0.75 cp Br. Sugar + 2 Eggs + 2.25 cp Flour + 1 tsp Baking soda + 1 tsp Salt + 16 oz Chocolate Chips + 1 tsp Vanilla + 1 cp Butter → 60 cookies

Application 6 eggs 60 cookies x = 180 cookies 2 eggs 0.75 cp Sugar + 0.75 cp Br. Sugar + 2 Eggs + 2.25 cp Flour + 1 tsp Baking soda + 1 tsp Salt + 16 oz Chocolate Chips + 1 tsp Vanilla + 1 cp Butter → 60 cookies So how many cookies could you make if you had unlimited ingredients but only 6 eggs? Use dimensional analysis! 6 eggs 60 cookies x = 180 cookies 2 eggs

Application 6 eggs 0.75 cp sugar x = 2.25 cp sugar 2 eggs 0.75 cp Sugar + 0.75 cp Br. Sugar + 2 Eggs + 2.25 cp Flour + 1 tsp Baking soda + 1 tsp Salt + 16 oz Chocolate Chips + 1 tsp Vanilla + 1 cp Butter → 60 cookies So how much sugar would you use to bake with 6 eggs? Use dimensional analysis! 6 eggs 0.75 cp sugar x = 2.25 cp sugar 2 eggs

So in chemistry: Let’s look at a chemical equation: CaCO3(s) + HCl (aq) →

So in chemistry: Let’s look at a chemical equation: CaCO3(s) + 2HCl (aq) → CaCl2(aq) + H2CO3(aq)

Important note: H2CO3 is called carbonic acid and is quite unstable. When you see it as a product, you need to break it apart into H2O + CO2!

So in chemistry: Let’s look at a chemical equation: CaCO3(s) + 2HCl (aq) → CaCl2(aq) + H2CO3(aq) CaCO3(s) + 2HCl (aq) → CaCl2(aq) + H2O(l) + CO2(g)

What does this equation mean? CaCO3(s) + 2HCl (aq) → CaCl2(aq) + H2O(l) + CO2(g) 1 mol CaCO3 reacts with 2 mol of HCl to produce 1 mol of CaCl2 and 1 mol of H2O and 1 mol of CO2

Mole Ratios!!!! The balanced equation gives you mole ratios, not mass (gram) ratios!!!

Answer with unit, substance, and rounded correctly Let’s practice CaCO3(s) + 2HCl (aq) → CaCl2(aq) + H2O(l) + CO2(g) How many moles of CO2 can be produced when 4.5 moles of HCl react in the reaction above? 4.5 mol HCl 1 mol CO2 x = 2.3 mol CO2 2 mol HCl Answer with unit, substance, and rounded correctly Start with given Use conv factor

New reaction Predict the products of hydrogen monofluroide reacting with aluminum carbonate. Write the balanced equation. 6 HF + Al2(CO3)3 → 2 AlF3 + 3 H2CO3 6 HF + Al2(CO3)3 → 2 AlF3 + 3 H2O + 3 CO2

Stoichiometry Practice How many moles of HF are required to react with 8.29 mol of Al2(CO3)3? 6 HF + Al2(CO3)3 → 2 AlF3 + 3 H2O + 3 CO2 8.29 mol Al2(CO3)3 6 mol HF x = 49.7 mol HF 1 mol Al2(CO3)3 Answer with unit, substance, and rounded correctly Start with given Use conv factor

Stoichiometry Practice How many moles of AlF3 can be produced when 33.5 moles of H2O are produced in the following reaction? 6 HF + Al2(CO3)3 → 2 AlF3 + 3 H2O + 3 CO2 2 mol AlF3 33.5 mol H2O x = 22.3 mol AlF3 3 mol H2O Answer with unit, substance, and rounded correctly Start with given Use conv factor

Last practice problem If 18.9 g of H2 reacts with excess O2, what mass of water will be produced? 2 H2 + O2  2 H2O 1 mol H2 18.9 g H2 2 mol H2O 18.02 g H2O x x x = 2.02 g H2 2 mol H2 1 mol H2O 169 g H2O

Time for Homework!