Characteristics of chemical reactions.ppt

chemical reaction equilibria thermodynamics ppt and chemical reactions ppt presentation
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Dr.SamuelHunt,United Arab Emirates,Teacher
Published Date:21-07-2017
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Chapter 8 Quantities in Chemical ReactionsGlobal Warming • Scientists have measured an average 0.6 °C rise in atmospheric temperature since 1860. • During the same period atmospheric CO 2 levels have risen 25%. • Are the two trends causal? www.ThesisScientist.comThe Source of Increased CO 2 • The primary source of the increased CO 2 levels are combustion reactions of fossil fuels we use to get energy. 1860 corresponds to the beginning of the Industrial Revolution in the U.S. and Europe. CH (g)  2 O (g)  CO (g)  2 H O(g) 2 C H (l)  25 O (g)  16 CO (g)  18 H O(g) 4 2 2 2 8 18 2 2 2 www.ThesisScientist.comQuantities in Chemical Reactions • The amount of every substance used and made in a chemical reaction is related to the amounts of all the other substances in the reaction. Law of Conservation of Mass. Balancing equations by balancing atoms. • The study of the numerical relationship between chemical quantities in a chemical reaction is called stoichiometry. www.ThesisScientist.comCounting and ratio’s It takes me .2 gal of gas to get to IVC. It is a very simple ratio: = What if I only had .1 gal 200 2X4’s, 3 sinks, 2 showers, you can make a house with 3 bathrooms and 3 bedrooms. What if you had 12 sinks…how many houses could you make. 200 3 2 = 1 3 3 www.ThesisScientist.comMaking Pancakes • The number of pancakes you can make depends on the amount of the ingredients you use. 1 cup flour + 2 eggs + ½ tsp baking powder  5 pancakes • This relationship can be expressed mathematically. 1 cup flour  2 eggs  ½ tsp baking powder  5 pancakes www.ThesisScientist.comMaking Pancakes, Continued • If you want to make more or less than 5 pancakes, you can use the number of eggs you have to determine the number of pancakes you can make.  Assuming you have enough flour and baking powder. 5 pancakes 8 eggs 20 pancakes 2 eggs www.ThesisScientist.comMaking Molecules Mole-to-Mole Conversions • The balanced equation is the “recipe” for a chemical reaction. • The equation 3 H (g) + N (g)  2 NH (g) tells us 2 2 3 that 3 molecules of H react with exactly 1 molecule 2 of N and make exactly 2 molecules of NH or: 2 3 3 molecules H 1 molecule N 2 molecules NH 2 2 3 • Since we count molecules by moles: 3 moles H 1 mole N 2 moles NH 2 2 3 www.ThesisScientist.comExample 8.1: • Sodium chloride, NaCl, forms by the following reaction between sodium and chlorine. How many moles of NaCl result from the complete reaction of 3.4 mol of Cl ? 2 Assume there is more than enough Na. 2 Na(s) + Cl (g)  2 NaCl(s) 2 www.ThesisScientist.comExample: How many moles of NaCl result from the complete reaction of 3.4 mol of Cl in 2 the reaction below? 2 Na(s) + Cl (g)  2 NaCl(s) 2 • Write down the given quantity and its units. Given: 3.4 mol Cl 2 www.ThesisScientist.comExample: Information: How many moles of NaCl Given: 3.4 mol Cl 2 result from the complete reaction of 3.4 mol of Cl in 2 the reaction below? 2 Na(s) + Cl (g)  2 NaCl(s) 2 • Write down the quantity to find and/or its units. Find: ? moles NaCl www.ThesisScientist.comExample: Information: How many moles of NaCl Given: 3.4 mol Cl 2 result from the complete Find: ? moles NaCl reaction of 3.4 mol of Cl in 2 the reaction below? 2 Na(s) + Cl (g)  2 NaCl(s) 2 • Collect needed conversion factors: According to the equation: 1 mole Cl 2 moles NaCl 2 www.ThesisScientist.comExample: Information: How many moles of NaCl Given: 3.4 mol Cl 2 result from the complete Find: ? moles NaCl reaction of 3.4 mol of Cl in 2 Conversion Factor: the reaction below? 1 mol Cl 2 mol NaCl 2 Na(s) + Cl (g)  2 NaCl(s) 2 2 • Write a solution map for converting the units: mol Cl mol NaCl 2 2 mol NaCl 1 mol Cl 2 www.ThesisScientist.comInformation: Example: Given: 3.4 mol Cl How many moles of NaCl 2 Find: ? moles NaCl result from the complete Conversion Factor: reaction of 3.4 mol of Cl in 2 1 mol Cl 2 mol NaCl the reaction below? 2 Solution Map: mol Cl mol NaCl 2 Na(s) + Cl (g)  2 NaCl(s) 2 2 • Apply the solution map: 2 mol NaCl 3.4 mol Cl moles NaCl 2 1 mol Cl 2 = 6.8 mol NaCl • Significant figures and round: = 6.8 moles NaCl www.ThesisScientist.comInformation: Example: Given: 3.4 mol Cl How many moles of NaCl 2 Find: ? moles NaCl result from the complete Conversion Factor: reaction of 3.4 mol of Cl in 2 1 mol Cl 2 mol NaCl the reaction below? 2 Solution Map: mol Cl mol NaCl 2 Na(s) + Cl (g)  2 NaCl(s) 2 2 • Check the solution: 3.4 mol Cl 6.8 mol NaCl 2 The units of the answer, moles NaCl, are correct. The magnitude of the answer makes sense because the equation tells us you make twice as many moles of NaCl as the moles of Cl . 2 www.ThesisScientist.comPractice • According to the following equation, how many moles of water are made in the combustion of 0.10 moles of glucose? C H O + 6 O 6 CO + 6 H O 6 12 6 2 2 2 www.ThesisScientist.comHow Many Moles of Water Are Made in the Combustion of 0.10 Moles of Glucose? Given: 0.10 moles C H O 6 12 6 Find: moles H O 2 Solution Map: mol C H O mol H O 6 12 6 2 6 mol H O 2 1 mol C H O 6 12 6 C H O + 6 O → 6 CO + 6 H O  1 mol C H O 6 mol H O Relationships: 6 12 6 2 2 2 6 12 6 2 Solution: 6 mol H O 2 0.10 mol C H O 0.6 mol H O 6 12 6 2 1 mol C H O 6 12 6 Check: 0.6 mol H O = 0.60 mol H O 2 2 Since 6x moles of H O as C H O , the number makes sense. 2 6 12 6 www.ThesisScientist.comMaking Molecules Mass-to-Mass Conversions • We know there is a relationship between the mass and number of moles of a chemical. 1 mole = Molar Mass in grams. • The molar mass of the chemicals in the reaction and the balanced chemical equation allow us to convert from the amount of any chemical in the reaction to the amount of any other. www.ThesisScientist.comExample 8.2—How Many Grams of Glucose Can Be Synthesized from 58.5 g of CO in 2 Photosynthesis? • Photosynthesis: 6 CO (g) + 6 H O(g)  C H O (s) + 6 O (g) 2 2 6 12 6 2 • The equation for the reaction gives the mole relationship between amount of C H O and 6 12 6 CO , but we need to know the mass relationship, 2 so the solution map will be: mol C H O g C H O g CO mol CO 6 12 6 6 12 6 2 2 www.ThesisScientist.comExample 8.2: • In photosynthesis, plants convert carbon dioxide and water into glucose (C H O ), according to the following 6 12 6 reaction. How many grams of glucose can be synthesized from 58.5 g of CO ? Assume there is more than enough 2 water to react with all the CO . 2 sunlight 6 CO (g)  6 H O(l)  6 O (g)  C H O (aq) 2 2 2 6 12 6 www.ThesisScientist.com