Type of Reactions. Chemical reactions can be classified as Combination reactions. Decomposition reactions. Single Replacement reactions.

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1 Chapter 5 Chemical Reactions and Quantities 5.3 Types of Reactions Type of Reactions Combination Chemical reactions can be classified as Combination reactions. In a combination reaction, Two or more elements (or simple compounds) combine to form one product Decomposition reactions. Single Replacement reactions. A + B A Double Replacement reactions. 1 Formation of MgO B 2Mg(s) + O2(g) 2MgO(s) 2Na(s) + Cl2(g) 2NaCl(s) SO3(g) + H2O(l) H2SO4(aq) 2 Decomposition 3 Decomposition of HgO In a decomposition reaction, One substance splits into two or more simpler substances. 2HgO(s) 2Hg(l) + O2(g) 2KClO3(s) 2KCl(s) + 3O2(g) 4 5 Single Replacement 1) combination or 2) decomposition: 1) combination or 2) decomposition: A. H2(g) + Br2(g) 2HBr(l) 1 A. H2(g) + Br2(g) 2HBr(l) B. Al2(CO3)3(s) Al2O3(s) + 3CO2(g) 2 B. Al2(CO3)3(s) Al2O3(s) + 3CO2(g) C. 4Al(s) + 3C(s) Al4C3(s) 1 C. 4Al(s) + 3C(s) Al4C3(s) 7 6 In a single replacement reaction, One element takes the place of a different element in a reacting compound. 8 Zn(s) + 2HCl(aq) ZnCl2(aq) + H2(g) Fe(s) + CuSO4(aq) FeSO4(aq) + Cu(s) 9 1

2 Zn and HCl is a Single Replacement Reaction Example of a Double Replacement Double Replacement In a double replacement, Two elements in the reactants exchange places. AgNO3(aq) + NaCl(aq) AgCl(s) + NaNO3(aq) ZnS(s) ZnCl2(aq) + H2S(g) + 2HCl(aq) ) single replacement 2) double replacement 1) single replacement 2) double replacement 1 A. 2Al(s) + 3H2SO4(aq) A. 2Al(s) + 3H2SO4(aq) Al2(SO4)3(s) + 3H2(g) B. Na2SO4(aq) + 2AgNO3(aq) Ag2SO4(s) + 2NaNO3(aq) C. 3C(s) + Fe2O3(s) 2Fe(s) + 3CO(g) Al2(SO4)3(s) + 3H2(g) Ag2SO4(s) + 2NaNO3(aq) 2Fe(s) + 3CO(g) 13 Ba3N2(s) 3 B. 2Ag(s) + H2S(aq) Ag2S(s) + H2(g) 4 C. SiO2(s) + 4HF(aq) SiF4(s) + 2H2O(l) 4 D. PbCl2(aq) + K2SO4(aq) 2KCl(aq) + PbSO4(s) 2 E. K2CO3(s) K2O(aq) + CO2(g) 16 Ba3N2(s) Ag2S(s) + H2(g) SiF4(s) + 2H2O(l) 2KCl(aq) + PbSO4(s) K2O(aq) + CO2(g) 15 Oxidation and Reduction 5.4 Oxidation-Reduction Reactions 1 A. 3Ba(s) + N2(g) 3Ba(s) + N2(g) 2Ag(s) + H2S(aq) SiO2(s) + 4HF(aq) PbCl2(aq) + K2SO4(aq) K2CO3(s) 2) decomposition 4) double replacement 14 Chapter 5 Chemical Reactions and Quantities Identify each reaction as 1) combination 3) single replacement A. B. C. D. E. 2 B. Na2SO4(aq) + 2AgNO3(aq) 1 C. 3C(s) + Fe2O3(s) 12 An oxidation-reduction reaction Provides us with energy from food. Provides electrical energy in batteries. Occurs when iron rusts. 4Fe(s) + 3O2(g) 2Fe2O3(s)

3 Electron Loss and Gain Oxidation and Reduction Zn and Cu 2+ An oxidation-reduction reaction Transfers electrons from one reactant to another. A Loss of Electrons is Oxidation Zn(s) Zn 2+ (aq) + 2e - (LEO) A Gain of Electrons is Reduction (GER) Cu 2+ (aq) + 2e - Cu(s) oxidation Zn(s) Zn 2+ (aq) + 2e- Silvery metal Cu 2+ (aq) + 2e- Blue reduction Cu(s) orange Electron Transfer from Zn to Cu 2+ Oxidation: electron loss Identify each of the following as 1) oxidation or 2) reduction: A. Sn(s) Sn 4+ (aq) + 4e B. Fe 3+ (aq) + 1e Fe 2+ (aq) C. Cl 2 (g) + 2e 2Cl - (aq) Identify each of the following as 1) oxidation or 2) reduction: 1 A. Sn(s) Sn 4+ (aq) + 4e 2 B Fe 3+ (aq) + 1e Fe 2+ (aq) 2 C. Cl 2 (g) + 2e 2Cl - (aq) Reduction: electron gain Writing Oxidation and Reduction Reactions Write the separate oxidation and reduction reactions for the following equation. 2Cs(s) + F 2 (g) 2CsF(s) Each cesium atom loses an electron to form cesium ion. 2Cs(s) 2Cs + (s) + 2e oxidation Fluorine atoms gain electrons to form fluoride ions. F 2 (s) + 2e - 2F (s) reduction In light-sensitive sunglasses, UV light initiates an oxidation-reduction reaction. uv light Ag + + Cl Ag + Cl A. Which reactant is oxidized? B. Which reactant is reduced? In light-sensitive sunglasses, UV light initiates an oxidation-reduction reaction. uv light Ag + + Cl Ag + Cl A. Which reactant is oxidized? Cl Cl Cl + 1e B. Which reactant is reduced? Ag + Ag + + 1e Ag

4 Identify the substances that are oxidized and reduced in each of the following reactions: A. Mg(s) + 2H + (aq) Mg 2+ (aq) + H 2 (g) B. 2Al(s) + 3Br 2 (g) 2AlBr 3 (s) A. Mg is oxidized Mg(s) Mg 2+ (aq) + 2e H + is reduced 2H + + 2e H 2 B. Al is oxidized 2Al 2Al e Br is reduced 2Br + 2e 2Br TYPES OF CHEMICAL REACTIONS Chemical reactions are often classified into categories according to characteristics of the reactions. The following is a useful classification scheme: Chapter 5 Chemical Reactions and Quantities 5.5 The Mole Collection Terms A collection term states a specific number of items. 1 dozen donuts = 12 donuts 1 ream of paper = 500 sheets 1 case = 24 cans A Mole of Atoms A mole is a collection that contains The same number of particles as there are carbon atoms in 12.0 g of carbon 12 C x atoms of an element (Avogadro s number). 1 mole element Number of Atoms 1 mole C = 6.02 x C atoms 1 mole Na = 6.02 x Na atoms 1 mole Au = 6.02 x Au atoms A Mole of a Compound Particle in One-Mole Samples Avogadro s Number A mole Of a covalent compound has Avogadro s number of molecules. 1 mole CO 2 = 6.02 x CO 2 molecules 1 mole H 2 O = 6.02 x H 2 O molecules Of an ionic compound contains Avogadro s number of formula units. 1 mole NaCl = 6.02 x NaCl formula units 1 mole K 2 SO 4 = 6.02 x K 2 SO 4 formula units TABLE 5.3 Avogadro s number 6.02 x can be written as an equality and two conversion factors. Equality: 1 mole = 6.02 x particles Conversion Factors: 6.02 x particles and 1 mole 1 mole 6.02 x particles

5 Using Avogadro s Number Avogadro s number is used to convert moles of a substance to particles. How many Cu atoms are in 0.50 mole Cu? 0.50 mole Cu x 6.02 x Cu atoms 1 mole Cu = 3.0 x Cu atoms Using Avogadro s Number Avogadro s number is used to convert particles of a substance to moles. How many moles of CO 2 are in 2.50 x molecules CO 2? 2.50 x molecules CO 2 x 1 mole CO 2 = 4.15 moles CO x molecules CO 2 1. The number of atoms in 2.0 moles Al is A. 2.0 Al atoms B. 3.0 x Al atoms C. 1.2 x Al atoms 2. The number of moles of S in 1.8 x atoms S is A. 1.0 mole S atoms B. 3.0 moles S atoms C. 1.1 x moles S atoms C. 1.2 x Al atoms 2.0 moles Al x 6.02 x Al atoms 1 mole Al B. 3.0 mole S atoms 1.8 x S atoms x 1 mole S 6.02 x S atoms Subscripts and Moles The subscripts in a formula give The relationship of atoms in the formula. The moles of each element in 1 mole of compound. Glucose C 6 H 12 O 6 In 1 molecule: 6 atoms C 12 atoms H 6 atoms O In 1 mole: 6 moles C 12 moles H 6 moles O Subscripts State Atoms and Moles 1 mole C 9 H 8 O 4 = 9 moles C 8 moles H 4 moles O Factors from Subscripts Subscripts used for conversion factors Relate moles of each element in 1 mole compound. For aspirin C 9 H 8 O 4 can be written as: 9 moles C 8 moles H 4 moles O 1 mole C 9H 8O 4 1 mole C 9H 8O 4 1 mole C 9H 8O 4 and 1 mole C 9H 8O 4 1 mole C 9H 8O 4 1 mole C 9H 8O 4 9 moles C 8 moles H 4 moles O A. How many moles O are in mole aspirin C 9 H 8 O 4? B. How many O atoms are in mole aspirin C 9 H 8 O 4? A. How many mole O are in mole aspirin C 9 H 8 O 4? mole C 9 H 8 O 4 x 4 moles O = mole O 1 mole C 9 H 8 O 4 subscript factor B. How many O atoms are in mole aspirin C 9 H 8 O 4? mole C 9 H 8 O 4 x 4 moles O x 6.02 x O atoms 1 mole C 9 H 8 O 4 1 mole O subscript Avogadro s factor Number = 3.61 x O atoms

6 Chapter 5 Quantities Chemical Reactions and Molar Mass 5.6 Molar Mass The molar mass is The mass of one mole of a substance. The atomic mass of an element expressed in grams. Give the molar mass to the nearest 0.1 g. A. K = B. Sn = Molar Mass of CaCl 2 Molar Mass of K 3 PO 4 Give the molar mass to the nearest 0.1 g. A. K = 39.1 g B. Sn = g For a compound, the molar mass is the sum of the molar masses of the elements in the formula. We calculate the molar mass of CaCl 2 to the nearest 0.1 g as follows. Element Number of Atomic Mass Total Mass Moles Ca g/mole 40.1 g Cl g/mole 71.0 g CaCl g Determine the molar mass of K 3PO 4 to 0.1 g. Element Number of Atomic Mass Total Mass in Moles K 3 PO 4 K g/mole g P g/mole 31.0 g O g/mole 64.0 g K 3PO g One-Mole Quantities Calculate the molar mass to the nearest 0.1g A. K 2 O = g Calculate the molar mass to the nearest 0.1g A. K 2O 2 moles K (39.1 g/mole) + 1 mole O (16.0 g/mole) 78.2 g g = 94.2 g 32.1 g 55.9 g 58.5 g g g B. Al(OH) 3 = g B. Al(OH) 3 1 mole Al (27.0 g/mole) + 3 moles O (16.0 g/mole) + 3 moles H (1.0 g/mole) 27.0 g g g = 78.0 g

7 Conversion Factors from Molar Mass Prozac, C 17 H 18 F 3 NO, is an antidepressant that inhibits the uptake of serotonin by the brain. What is the molar mass of Prozac? 1) 40.0 g/mole 2) 262 g/mole 3) 309 g/mole Prozac, C 17 H 18 F 3 NO, is an antidepressant that inhibits the uptake of serotonin by the brain. What is the molar mass of Prozac? 3) 309 g/mole 17C (12.0 g) + 18H (1.0 g) + 3F (19.0 g) + 1N (14.0 g) + 1 O (16.0 g) = 204 g + 18 g g g Methane CH 4 known as natural gas is used in gas cook tops and gas heaters. 1 mole CH 4 = 16.0 g The molar mass of methane can be written as conversion factors g CH 4 and 1 mole CH 4 1 mole CH g CH Calculations Using Molar Mass Acetic acid C 2H 4O 2 gives the sour taste to vinegar. Write two molar mass conversion factors for acetic acid. Acetic acid C 2H 4O 2 gives the sour taste to vinegar. Write two molar mass factors for acetic acid. 1 mole of acetic acid = 60.0 g acetic acid 1 mole acetic acid and 60.0 g acetic acid 60.0 g acetic acid 1 mole acetic acid Mole factors are used to convert between the grams of a substance and the number of moles. Grams Mole factor Moles Calculating Grams from Moles Aluminum is often used for the structure of lightweight bicycle frames. How many grams of Al are in 3.00 moles of Al? 3.00 moles Al x 27.0 g Al = 81.0 g Al 1 mole Al mole factor for Al The artificial sweetener aspartame (Nutri-Sweet) C 14H 18N 2O 5 is used to sweeten diet foods, coffee and soft drinks. How many moles of aspartame are present in 225 g of aspartame? Calculate the molar mass of C 14H 18N 2O 5. (14 x 12.0) + (18 x 1.0) + (2 x 14.0) + (5 x 16.0) = 294 g/mole Set up the calculation using a mole factor. 225 g aspartame x 1 mole aspartame 294 g aspartame mole factor(inverted) = mole aspartame