Name: Period: Date: Unit 7: Chemical Reactions Lesson 6: Mole Ratios

Size: px

Start display at page:

Download "Name: Period: Date: Unit 7: Chemical Reactions Lesson 6: Mole Ratios"

Avice Elinor Byrd
5 years ago
Views:

Name: Period: Date: Unit 7: Chemical Reactions Lesson 6: Mole Ratios By the end of today, you will have an answer to: How do you determine how much of a substance you will produce in a reaction?

What is challenging about answering this question? What is a MOLE? But how big is each mole REALLY?

1 Name: Period: Date: Unit 7: Chemical Reactions Lesson 6: Mole Ratios By the end of today, you will have an answer to: How do you determine how much of a substance you will produce in a reaction? DO NOW: Balance the following reactions: 1. AlBr 3 + K 2 SO 4 KBr + Al 2 (SO 4 ) 3 2. CH 4 + O 2 CO 2 + H 2 O CATALYST How do we figure out the number of atoms in this cup of water? What is challenging about answering this question? What is a MOLE? But how big is each mole REALLY? Term Dozen Ream Mole Quantity 602,200,000,000,000,000,000,000 1 mole = So, if we start out with one mole of copper, that is really 602,000,000,000,000,000,000,000 atoms of copper. In chemistry, the COEFFICIENT represents the NUMBER OF MOLES of each substance Example: K + S 8 K 2S 1) How many moles of K are used in this reaction? 2) How many moles of S 8 are used in this reaction? 3) How many moles of K 2S are produced in this reaction?

2 Mole to mole ratios: In any chemical reaction, we can predict the amount of reactant and product present using mole to mole ratios. What are the three ways we can represent ratios? There are 12 boys and 13 girls in class. What is the ratio of boys to girls in class? Decimal Fraction Ratio notation Chemistry Example: Mg + O 2 MgO 1. What is the number of moles of Mg? 2. What is the number of moles of O 2? 3. What is the number of moles of MgO? 4. What is the mole to mole ratio between Mg and O 2? (Represent in fraction form, please.) How do we use mole ratios to PREDICT the amount of product or reactant we need for any reaction? EXAMPLE: Given the balanced equation representing a reaction: 2C 2H 6 + 7O 2 4CO 2 + 6H 2O Determine the total number of moles of oxygen that react completely with 8.0 moles of C 2H 6. [1] How many moles of H 2O can be produced from 10 moles of O 2? [1]

3 Name: CW 7.6: Mole Ratios Date: 10 points 1. The gram-formula mass of a compound is 48 grams. The mass of 1.0 mole of this compound is (1) 1.0 g (3) 48 g (2) 4.8 g (4) 480 g 2. Given the balanced equation representing a reaction: 2CO(g) + O 2(g) 2CO 2(g) What is the mole ratio of CO(g) to CO 2(g) in this reaction? (1) 1:1 (3) 2:1 (2) 1:2 (4) 3:2 If a student reacted 7 moles of O 2, how much CO 2 would be produced? 3. Given the balanced equation: 2C + 3H 2 C 2H 6 What is the total number of moles of C that must completely react to produce 2.0 moles of C 2H 6? (1) 1.0 mol (3) 3.0 mol (2) 2.0 mol (4) 4.0 mol If a student wished to produce 15 moles of C 2H 6, how much H 2 would he have needed to start with? If a student had 28 moles of solid carbon, would that be enough to produce 15 moles of C 2H 6? Explain: 4. A tablet of one antacid contains citric acid, H 3C 6H 5O 7, and sodium hydrogen carbonate, NaHCO 3. When the tablet dissolves in water, bubbles of CO 2 are produced. This reaction is represented by the incomplete equation below. H 3C 6H 5O 7(aq) + 3NaHCO 3(aq) Na 3C 6H 5O 7(aq) + 3CO 2(g) + 3 (l) Determine the total number of moles of sodium hydrogen carbonate that will completely react with mole of citric acid. [1] What would be the mass of one mole of citric acid? How could you determine the mass of three moles of citric acid?

4 5. A portable propane-fueled lantern contains a mesh silk bag coated with metal hydroxides. The primary metal hydroxide is yttrium hydroxide. When the silk bag is installed, it is ignited and burned away, leaving the metal hydroxide coating. The coating forms metal oxides that glow brightly when heated to a high temperature. During a test, a propane lantern is operated for three hours and consumes 5.0 moles of propane from the lantern s tank. The balanced equation below represents the combustion of propane. C 3H 8 + 5O 2 3CO 2 + 4H 2O + energy Determine the total number of moles of CO 2 produced during the lantern test. [1] Determine the number of moles of O 2 that must have been used during this test. [1]

5 Name: Date: HW 7.6: Mole Ratios 10 points 1. Given the balanced equation representing the reaction between propane and oxygen: C 3H 8 + 5O 2+ 3CO 2 + 4H 2O According to this equation, which ratio of oxygen to propane is correct? Base your answers to questions 2 and 3 on the information below. Given the balanced equation representing a reaction: C 3H 8(g) + 5O 2(g) CO 2(g) + 4H 2O(g) 2. What is the total number of moles of O 2(g) required for the complete combustion of 1.5 moles of C 3H 8? (1) 0.30 mol (3) 4.5 mol (2) 1.5 mol (4) 7.5 mol 3. If you began with 25 moles of O 2, how much CO 2 could be produced? Name: Date: HW 7.6: Mole Ratios 10 points 1. Given the balanced equation representing the reaction between propane and oxygen: C 3H 8 + 5O 2+ 3CO 2 + 4H 2O According to this equation, which ratio of oxygen to propane is correct? Base your answers to questions 2 and 3 on the information below. Given the balanced equation representing a reaction: C 3H 8(g) + 5O 2(g) CO 2(g) + 4H 2O(g) 2. What is the total number of moles of O 2(g) required for the complete combustion of 1.5 moles of C 3H 8? (1) 0.30 mol (3) 4.5 mol (2) 1.5 mol (4) 7.5 mol 3. If you began with 25 moles of O 2, how much CO 2 could be produced?

6 4. Some dry chemicals can be used to put out forest fires. One of these chemicals is NaHCO 3. When NaHCO 3(s) is heated, one of the products is CO 2(g), as shown in the balanced equation below. 2NaHCO 3(s) + heat Na 2CO 3(s) + H 2O(g) + CO 2(g) Determine the total number of moles of CO 2(g) produced when 7.0 moles of NaHCO 3(s) is completely reacted. [1] 5. Given the reaction: CH 4(g) + 2O 2(g) CO 2(g) + 2H 2O(g) How many moles of oxygen are needed for the complete combustion of 3.0 moles of CH 4(g)? 4. Some dry chemicals can be used to put out forest fires. One of these chemicals is NaHCO 3. When NaHCO 3(s) is heated, one of the products is CO 2(g), as shown in the balanced equation below. 2NaHCO 3(s) + heat Na 2CO 3(s) + H 2O(g) + CO 2(g) Determine the total number of moles of CO 2(g) produced when 7.0 moles of NaHCO 3(s) is completely reacted. [1] 5. Given the reaction: CH 4(g) + 2O 2(g) CO 2(g) + 2H 2O(g) How many moles of oxygen are needed for the complete combustion of 3.0 moles of CH 4(g)?

Practice Test. Moles & Stoich. Page What is the total number of nitrogen atoms in 0.25 mole of NO2 gas? (1)

Practice Test. Moles & Stoich. Page What is the total number of nitrogen atoms in 0.25 mole of NO2 gas? (1) 1. What is the total number of nitrogen atoms in 0.25 mole of NO2 gas? (1) 1.5 10 23 (3) 3.0 10 23 (2) 6.0 10 23 (4) 1.2 10 24 2. Which quantity of O2 contains exactly 3.01 10 23 molecules? (1) 0.250 mole