CHEMISTRY - MCMURRY 7E CH.3 - MASS RELATIONSHIPS IN CHEMICAL REACTIONS

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2 ONEPT: ALLOYS An alloy represents a mixture composed of two or more elements in which at least one of the elements is a metal. The predominant metal component, which is can be up to 90% or higher in terms of composition is referred to as the or metal. The minor components, which usually average around 1% in terms of composition, are referred to as the. Alloys can be created by three different methods: 1) Heating the alloy components into liquids, mix them together and allowing them to cool into a. 2) : turning the components into powders, mixing them together and allowing them to fuse. 3) : firing beams of ions at the surface of the host metal and allowing other components to mix. Alloys are classified into two major types: A(n) alloy is where some of the host metal atoms have been replaced by other metal atoms that have a similar size. A(n) alloy is where the empty spaces between the host metal atoms have been taken up by smaller metal atoms. Other common alloys that are good to remember include: copper (host metal), tin, manganese, phosphorus, aluminum, silicon. tin (host metal), copper, lead, antimony. iron (host metal), chromium with very small amounts of carbon, nickel, manganese & molybdenum. Page 2

3 ONEPT: OMMON POLYATOMI IONS Polyatomic ions are compounds made up of different elements, usually only, and possess a. Singly harged ation (Positive Ion) NH4 + Ammonium Doubly harged Anions (Negative Ions) O3 2 arbonate Doubly harged ation (Positive Ion) ro4 2 hromate Hg2 2+ Mercury (I) r2o7 2 Dichromate Singly harged Anions (Negative Ions) O2 2 Peroxide H3O2 or 2H3O2 Acetate SO4 2 Sulfate N yanide Sulfite OH Hydroxide MnO4 Permanganate Triply harged Anions (Negative Ions) NO3 Nitrate PO4 3 Phosphate Nitrite Phosphite Doubly & Singly harged Anions (Negative Ions) HPO4 2 H2PO4 HO3 HSO4 Hydrogen Phosphate Dihydrogen Phosphate Hydrogen arbonate or Bicarbonate Hydrogen Sulfate or Bisulfate Page 3

4 ONEPT: POLYATOMI IONS w/ HALOGENS Polyatomic ions containing halogens are sometimes referred to as halogens or halogen. These compounds share 4 common characteristics: These compounds use the same system for naming: PRATIE: Name each of the following compounds. a. BrO4 b. FO2 c. lo d. IO3 Page 4

5 ONEPT: NAMING MOLEULAR OMPOUNDS Features: & Because molecular compounds combine in different proportions to form different compounds, we must use numerical prefixes. Rules for Naming: a. The first nonmetal is named normally and uses all numerical prefixes except. b. The second nonmetal keeps its base name but has its ending changed to. EXAMPLE: Write the formula for each of the following compounds. a. Disulfur monobromide b. Iodine Tetrachloride PRATIE: Give the systematic name for each of the following compounds: a. O b. N2S4 c. IO5 Page 5

6 ONEPT: IONI OMPOUNDS In the early days of chemistry, newly discovered compounds were given fancy names such as morphine, quicklime and muriatic acid. Since then thousands of new compounds have been discovered and named under a system called. Metals tend to electrons to become positively charged ions called. Nonmetals tend to electrons to become negatively charged ions called. Page 6

7 ONEPT: NAMING BINARY IONI OMPOUNDS Features: & Rules for Naming: a. The metal is named and written first. If the metal is a transition metal we must use a to describe its positive charge. b. The nonmetal keeps its base name but has its ending changed to. EXAMPLE: Provide the molecular formula or name for each of the following compounds. a. alcium phosphide b. oo PRATIE: Provide the molecular formula or name for each of the following compounds. a. AlBr3 b. Lead (IV) sulfide c. SnO2 Page 7

8 ONEPT: NAMING IONI OMPOUNDS w/ POLYATOMIS Features: & Rules for Naming: a) The metal keeps its name and is named and written first. If the metal is a transition metal we must use a to describe its positive charge. b) Name the polyatomic as you would normally. EXAMPLE: Write the formula for each of the following compounds: a. Iron (III) Acetate b. opper (I) phosphate c. Strontium arbonate d. Ammonium Nitrite EXAMPLE: Give the systematic name for each of the following compounds: a. Pb(rO4)2 b. Ga(lO4)3 c. Mn(HSO4)2 d. Ba(N)2 Page 8

9 ONEPT: NAMING IONI HYDRATES Features: & uso 4 5 H 2 O Rules for Naming the Ionic ompound portion: a. The metal is named normally and written first. If the metal is a transition metal we must use a to describe its positive charge. b. The nonmetal keeps the first part of its name but has its ending changed to. c. Name the polyatomic as you would normally. Rules for Naming the H2O portion: a. The H2O portion will be called. b. To describe the number of H2O molecules use these prefixes. EXAMPLE: Write the formula for each of the following compounds. a. alcium carbonate hexahydrate b. Lead (IV) Sulfate pentahydrate PRATIE: Give the systematic name for each of the following compounds: a) K2r2O7 3 H2O b) Sn(SO3)2 4 H2O Page 9

10 ONEPT: NAMING AIDS 1. BINARY AIDS Features: + Rules for Naming: a. The prefix will be. b. Use the base name of the nonmetal. c. The suffix will be. EXAMPLE: Write the formula for each of the following compounds: a. Hydroiodic acid b. Hydroselenic acid c. Hydrofluoric acid PRATIE: Give the systematic name for each of the following compounds: a. HBr b. H2S c. HN 2. OXOAIDS or OXYAIDS Features: + Rules for Naming: a. If the polyatomic ion ends with ate then change the ending to. b. If the polyatomic ion ends with ite then change the ending to. EXAMPLE: Give the systematic name or formula for each of the following compounds: a. H2O3 b. Nitric acid c. H2SO4 PRATIE: Give the systematic name or formula for each of the following compounds: a. Hypobromous acid b. HlO3 c. Acetic acid Page 10

11 ONEPT: EMPIRIAL FORMULA The empirical formula is also known as the. It represents the ratio of moles of each element in the compound. The molecular formula is also known as the. 6 H 12 O 6 = It represents the ratio of moles of each element in the compound. EXAMPLE: What is the empirical formula of dimethylhydrazine, 2H8N2, a colorless liquid used as a rocket fuel? EXAMPLE: Elemental analysis of a sample of an ionic compound showed 2.82 g of Na, 4.35 g of l, and 7.83 g of O. What is the empirical formula and name of the compound? EXAMPLE: After a workout session, lactic acid (M = g/mol) forms in muscle tissue and is responsible for muscle soreness. Elemental analysis shows that this compound contains 40%, 6.7% H and 53.3% O. Determine the molecular formula. Page 11

12 ONEPT: OMBUSTION ANALYSIS Under a combustion reaction a compound made of or reacts with. The products formed will be and. EXAMPLE: A g sample contains carbon, hydrogen and oxygen and undergoes complete combustion to produce g of O2 and g of H2O. What is the empirical formula of the compound? Page 12

13 ONEPT: HEMIAL OMPOSITION The mass per mole of an element is called its (M). The mass per mole of a compound is called its (M). They both have the units of. 1. Elements. To find mass of an element just look up its atomic mass in the periodic table. EXAMPLE: What is the total mass of each of the following elements? a. Sodium b. Gold c. Mercury 2. ompounds. The mass of a compound is the sum of the individual masses of the elements in the chemical formula. EXAMPLE: What is the total mass of each of the following compounds? a. N2O5 b. 12H22O11 c. (NH4)3PO4 Page 13

14 ONEPT: MASS PERENT Mass or weight percent is the percentage of a given element in a compound. Mass Percent (%) = (Massomponent) 100 (TotalMass) EXAMPLE: What is the percentage of carbon in sodium hydrogen carbonate, NaHO3? EXAMPLE: A sample of toothpaste contains tin (II), SnF2. Analysis of a 5.25 g sample contains 8.77 x 10-3 g of F. What is the percentage of tin (II) fluoride in the sample? PRATIE: Hemoglobin contains 0.33% iron and has a molecular weight of 68 kg. How many iron atoms are in each molecule of hemoglobin? Page 14

15 ONEPT: BALANING HEMIAL REATIONS When balancing an equation always make sure the and of atoms on both sides of the arrow are equal. EXAMPLE: Write balanced equations for each of the following by inserting the correct coefficients in the blanks: a. Al (s) + l2 (g) All3 (s) b. Ba3(PO4)2 (s) + KOH (aq) K3PO4 (aq) + Ba(OH)2 (aq) c. 4H10 (aq) + O2 (g) O2 (g) + H2O (l) Page 15

16 ONEPT: GROUP REATIVITY The central principle of Organic hemistry is based on the. The reactivity of an organic compound is all based on which type is present. H 3 OH H 3 H 3 O H 2 H 2 H 2 H 2 H 3 Tetrahydrocannabinol (TH) Alkane Alkene Alkyne Alcohol Amine Aldehyde Ketone arboxylic Acid Ester Page 16

17 ONEPT: GROUP REATIVITY (PRATIE) EXAMPLE: In each of the following molecules, identify the type(s) of functional groups present. a. b. O OH PRATIE: In each of the following molecules, identify the type(s) of functional groups present. a. b. O O Page 17

18 ONEPT: STOIHIOMETRI REATIONS 2 H 2 (g) + 1 O 2 (g) 2 H 2 O (g) In the above equation the numbers that are in bold are called. They tell us the number of of each compound that reacts. This numerical relationship between compounds in a balanced equation is called. STOIHIOMETRI HART Before we get into solving stoichiometric reactions lets work out a plan of attack. Entities means, or. Entities of Given Entities of Unknown Moles of Given Moles of Unknown Grams of Given Grams of Unknown Use this chart when given a chemical equation with the quantity of a compound or element and asked to find the quantity of another compound or element. 2 H EXAMPLE: How many grams of H2O are produced when 12.3 g H2 reacts? 2 (g) + 1 O 2 (g) 2 H 2 O (g) Page 18

19 PRATIE: STOIHIOMETRI REATIONS EXAMPLE 1: The oxidation of chromium solid is represented by the following equation: 4 r (s) + 3 O2 (g) 2 r2o3 (s) a. How many moles of chromium (III) oxide are produced when g r reacts with excess oxygen gas? b. How many grams of O2 were needed to produce 4.28 x 10 3 molecules r2o3? EXAMPLE 2: If the density of ethanol, H3H2OH, is g/ml, how many milliliters of ethanol are needed to produce 4.8 g of H2O in the following reaction? H3H2OH (l) + 3 O2 2 O2 (g) + 3 H2O (l) PRATIE: Dinitrogen monoxide gas decomposes to form nitrogen gas and oxygen gas. How many molecules of oxygen are formed when 8.00 g of dinitrogen monoxide decomposes? Page 19

20 ONEPT: LIMITING REAGENT In a chemical reaction the reactant that is consumed when a reaction occurs and determines the maximum amount of product formed is called the. The amount of product it forms is called the yield. The reactant that remains after the completion of the chemical reaction is called the reactant. EXAMPLE: hromium (III) oxide reacts with hydrogen sulfide (H2S) gas to form chromium (III) sulfide and water: r2o3 (s) + 3 H2S (g) r2s3 (s) + 3 H2O (l) [Balanced] a. What is the mass of chromium (III) sulfide formed when g r2o3 reacts with g H2S? b. Identify the limiting reactant, excess reactant and theoretical yield. c. What mass of excess reactant remains? Page 20

21 ONEPT: PERENT YIELD The percent yield of a reaction is used to determine how effective the chemist was in creating their desired products. A high percent yield would signify that the reaction is. EXAMPLE 1: A scientist performs an experiment in the laboratory and obtains g r2s3. If his calculations on scratch paper give him a theoretical yield of g what is the percent yield? PRATIE: onsider the following balanced chemical reaction: 2 6H6 (l) + 15 O2 (g) 12 O2 (g) + 6 H2O (l) a. If a 2.6 g sample of 6H6 reacted with excess O2 to produce 1.25 g of water, what is the percent yield of water? b. If the above reaction only went to 75% completion, how many moles of O2 would be produced if 1.57 x 10-5 molecules of 6H6 were reacted with excess oxygen? Page 21