Chemistry Applications in Engineering Laboratory (ENG 202) PDF

1 CHEMISTRY APPLICATIONS IN ENGINEERING LABORATORY (ENG 202) Activity 1: Formula Naming and Writing ACTIVITY 1 CHEMICAL FORMULA NAMING AND WRITING 1.1 WRITING CHEMICAL FORMULAS The study of form...

1 CHEMISTRY APPLICATIONS IN ENGINEERING LABORATORY (ENG 202) Activity 1: Formula Naming and Writing ACTIVITY 1 CHEMICAL FORMULA NAMING AND WRITING 1.1 WRITING CHEMICAL FORMULAS The study of formula writing covers a vast array of chemical formulas. At times, students encounter confusion and difficulty as so many new names come up in the discussion. A solid foundation on the fundamental principles and basic nomenclature rules can provide a better understanding of the system of chemical formula naming and writing. The names and formulas of inorganic compounds are written in such a way that every compound can be named from its formula and each formula has a name particular to that specific compound. An organization of chemists called the International Union of Pure and Applied Chemistry (IUPAC) developed a systematic and simplified way of writing and naming chemical formulas. A chemical formula is a representation of the number and kind of atoms in a molecule of a substance. It is used as a symbolic representation of the compound, as the name of the substance can sometimes be too long and impractical to use in scientific discussions. Types of Formulas Molecular formulas (MF) give the actual number of atoms per molecule or per mole of a compound. Example: Hydrogen Peroxide MF: H 2O2 1. Empirical formulas give the simplest whole-number ratios in which atoms combine to form a compound. These ratios are always expressed as whole numbers to conform to the assumption of the Law of Multiple Proportions that fractions of atoms cannot combine. Example: Hydrogen Peroxide EF: HO 2. Structural formulas show the bonding arrangement of the atoms within a molecule. Example: Hydrogen Peroxide SF: For the exclusive use of UST Engineering students 2 CHEMISTRY APPLICATIONS IN ENGINEERING LABORATORY (ENG 202) Activity1: Formula Naming and Writing 3. Lewis electronic formulas (electron dot formulas) show how the electron pairs are arranged in the molecule. Example: Hydrogen Peroxide LEF: The derivation of formulas of compounds consisting of two elements permits a generalization for writing the formulas of other compounds where either of these elements is present. Examine the following compounds: HCl 1 H atom combines with 1 Cl atom H2 O 2 H atoms combine with 1 O atom NH3 3 H atoms combine with 1 N atom SiH4 4 H atoms combine with 1 Si atom CaH2 2 H atoms combine with 1 Ca atom These formulas show that more than one atom of hydrogen can combine with one atom of the other element. By convention, the valence of hydrogen is 1+. Therefore, the common valence of an element can be defined as the number of hydrogen atoms that combine with the atom of that element. The common valences of the elements in the above formulas are: H, 1+ Cl, 1‒ N, 3‒ Ca, 2+ O, 2‒ Si, 4+ The common valence of an element expresses only its combining capacity, not the presence or absence of ions. Common valences make it possible to predict the formulas of binary compounds which are compounds consisting of two elements. It is convenient to consider valence as an electrical or magnetic phenomenon. Thus, a metal almost always has a positive valence while a non-metal usually has a negative valence. When an atom loses or gains electrons, an ion is formed. The valence number, positive or negative, indicates the number of electrons lost or gained by the atom. The For the exclusive use of UST Engineering students 3 CHEMISTRY APPLICATIONS IN ENGINEERING LABORATORY (ENG 202) Activity 1: Formula Naming and Writing “signed valence” is the oxidation state of the element. It is worth noting that some elements (commonly transition metals) may exist with two or more oxidation states. Compounds form to become more stable; two elements combine in such a way that the atoms are in their simplest ratio and that their oxidation numbers will add to zero. Example: (a) HCl (H+, Cl‒) (b) H2O (H+, O2‒) For some components, the charge on the ion is the same as the common valence. These are called ionic compounds. Certain combinations of two or more elements remain and behave as units during many chemical reactions. These combinations are referred to as radicals or polyatomic ions. Examples: SO42‒ , NH4+, HCO3‒ RULES IN WRITING CHEMICAL FORMULAS: 1. Symbols of metals, non-metals, and inert gases remain unchanged in the formulas where they are found. Examples: Fe, Zn, Mg, S, C, Ne, Ar 2. Symbols of common gaseous elements are written correctly by taking two atoms of these elements forming more stable diatomic molecules. These gaseous compounds are: O2, H2, N2, F2, I2, Br2, Cl2 3. Inorganic Compounds: (a) Write the cation first and then the anion. Example: Na Cl Na SO4 NH4 PO4 (b) Indicate their respective oxidation states. Example: Na+ Cl‒ Na+ SO42- NH4+ PO43‒ For the exclusive use of UST Engineering students 4 CHEMISTRY APPLICATIONS IN ENGINEERING LABORATORY (ENG 202) Activity1: Formula Naming and Writing (c) Make a total oxidation number equal to zero by applying the “criss- cross” method. Example: NaCl Na2SO4 (NH4)3 PO4 Note: The subscript “1” is never written. The radicals should be enclosed in parentheses. Elements and ions with the same valence numbers cancel out. 1.2 NAMING CHEMICAL FORMULAS Communication is impossible without a rational system of naming substances. Each discipline finds it necessary to develop its own systematic language. Modern rules provide a standardized system of naming more than 4 million unique substances, making the nomenclature possible and easier to familiarize with. I. BINARY COMPOUNDS are substances consisting of two types of elements 1. Covalent Compounds which usually involve 2 non-metallic elements use the Greek prefixes, mono, di, tri, tetra, penta…etc, to indicate the number of atoms of each element present in the compound. The second non-metal usually ends in –ide. Examples: CO carbon monoxide CO2 carbon dioxide N2 O dinitrogen monoxide N2O4 dinitrogen tetroxide PCl3 phosphorus trichloride PCl5 phosphorus pentachloride Note: The prefix “mono” is never written for the first element. For the exclusive use of UST Engineering students 5 CHEMISTRY APPLICATIONS IN ENGINEERING LABORATORY (ENG 202) Activity 1: Formula Naming and Writing 2. Binary Acids: Aqueous solutions of acids (aq) are distinguished by the prefix hydro– and ending –ic. Examples: HCl (aq) hydrochloric acid H2S (aq) hydrosulfuric acid HI (aq) hydroiodic acid HBr (aq) hydrobromic acid Note: For the combination of these elements in the gaseous form, the rules for naming binary salts apply. 3. Salts: These consist of a metallic cation and a non-metallic anion. The element which forms a positive ion is written first and the second element is abbreviated and given the suffix –ide. Unlike in covalent compounds, Greek prefixes are not used in naming this class of compounds. Examples: NaCl sodium chloride K2 S potassium sulfide LiH lithium hydride CaO calcium oxide MgBr2 magnesium bromide BaF2 barium fluoride When metals with variable valences are involved, it is necessary to distinguish the various salts by one of the following systems. A. OUS – IC system: It is the traditional system not recommended by IUPAC. It applies the suffix –ic for the element with the higher oxidation state and –ous for that with the lower oxidation state. For the exclusive use of UST Engineering students 6 CHEMISTRY APPLICATIONS IN ENGINEERING LABORATORY (ENG 202) Activity1: Formula Naming and Writing Example: FeCl2 ferrous chloride FeCl3 ferric chloride Hg2O mercurous oxide HgO mercuric oxide B. Stock system: Alfred Stock, famous for his work on the chemistry of boron and silicon hydrides, introduced the system of using Roman numerals to indicate the oxidation state of the first element. Examples: FeCl2 iron (II) chloride FeCl3 iron (III) chloride Hg2O mercury (I) oxide HgO mercury (II) oxide 4. Compounds containing Polyatomic Ions: Naming of ionic compounds that contain polyatomic ions follows the same rules as the naming for other ionic compounds: the name of the cation and the name of the anion are combined. Numerical prefixes are not used except if the name of the ion itself contains a numerical prefix, such as dichromate and triiodide. Examples: NaOH sodium hydroxide Ca(OH)2 calcium hydroxide KCN potassium cyanide Fe(OH)3 ferric hydroxide NH4Cl ammonium chloride LiHCO3 lithium bicarbonate BaSO4 barium sulfate K2 Cr2O7 potassium dichromate For the exclusive use of UST Engineering students 7 CHEMISTRY APPLICATIONS IN ENGINEERING LABORATORY (ENG 202) Activity 1: Formula Naming and Writing 5. Trivial Names – These are common, non-systematic names that are assigned arbitrarily to some compounds. These names have been adopted for their convenience, practicality, and ease of communication. Examples: H2 O water HCl muriatic acid NH3 ammonia Al2O3 alumina PH3 phosphine NaHCO3 baking soda AsH3 arsine CaCO3 marble CH4 marsh gas N2 O laughing gas CaO lime NaOH lye NaCl table salt NaClO chlorox 6. Peroxides are oxygen atoms with a single covalent bond between them. Care must be taken to distinguish between peroxides and normal oxides. Examples: BaO2 barium peroxide BaO barium oxide Na2O2 sodium peroxide Na2 O sodium oxide II. TERNARY COMPOUNDS Ternary Acids and Salts Ternary compounds are compounds that consist of three different elements. The oxides of non-metals react with water to form solutions, which are acidic. In some cases, there may be a series of oxyacids, each one containing the non–metal in a different oxidation state. In order to distinguish between these acids and their respective salts, the following system has been devised: For the exclusive use of UST Engineering students 8 CHEMISTRY APPLICATIONS IN ENGINEERING LABORATORY (ENG 202) Activity1: Formula Naming and Writing Oxidation state of Cl Acid Name 1+ HClO Hypochlorous acid 3+ HClO2 Chlorous acid 5+ HClO3 Chloric acid 7+ HClO4 Perchloric acid Oxidation state of Cl Salt Name 1+ NaClO Sodium hypochlorite 3+ NaClO2 Sodium chlorite 5+ NaClO3 Sodium chlorate 7+ NaClO4 Sodium perchlorate Note that for acids ending in –ous, the corresponding salt ends in –ite, and for acids ending in –ic, the salts end in –ate. In addition the prefix hypo–, Greek for under, is used to denote the lowest oxidation state of the non–metal. The prefix per–, from the Greek hyper, meaning above, is used to denote highest oxidation state of the non –metal. For the exclusive use of UST Engineering students 9 CHEMISTRY APPLICATIONS IN ENGINEERING LABORATORY (ENG 202) Activity 1: Formula Naming and Writing Part 1 and 2 will be discussed as Examples in Class (Synchronous Session). Part 3 Answers will be then submitted using the Treatment of Data Template for Activity 1 Practice 1: Name the following compounds Part 1. Naming of chemical compounds 1. SO2 2. PBr5 3. SnCl4 4. MgCl2 5. PbS2 6. Ca(CN)2 7. HCN (aq) 8. Al(OH)3 9. H2SO4 (in water) 10. Ca3(PO4)2 For the exclusive use of UST Engineering students 10 CHEMISTRY APPLICATIONS IN ENGINEERING LABORATORY (ENG 202) Activity1: Formula Naming and Writing Part 2. Naming of chemical compounds 1. Mg(ClO3)2 2. NH4NO3 3. HBrO (in water) 4. SnI4 5. HI (g) 6. CF4 7. Na2S 8. Cl2O7 9. Na2SO4 10. PbS2 For the exclusive use of UST Engineering students 11 CHEMISTRY APPLICATIONS IN ENGINEERING LABORATORY (ENG 202) Activity 1: Formula Naming and Writing Practice 2: Fill in the following table with the name of the binary acid, the formula of its sodium salt, and the corresponding name of its sodium salt. Binary acid Name of acid Formula for Name of sodium salt sodium salt HI HF HIO HIO2 HIO3 HIO4 H3AsO4 H3AsO3 HNO3 HNO2 For the exclusive use of UST Engineering students 12 CHEMISTRY APPLICATIONS IN ENGINEERING LABORATORY (ENG 202) Activity1: Formula Naming and Writing Practice 3: Give the chemical formula of the compounds with the following names. Part 1. Formula writing 1. calcium nitrate 2. iron (III) sulfate 3. ammonium phosphate 4. tin (II) sulfite 5. silver phosphate 6. zinc cyanide 7. lead (IV) oxide 8. ferric ferrocyanide 9. cuprous sulfide 10. chlorine gas For the exclusive use of UST Engineering students 13 CHEMISTRY APPLICATIONS IN ENGINEERING LABORATORY (ENG 202) Activity 1: Formula Naming and Writing Practice 3: Give the chemical formula of the compounds with the following names. Part 2. Formula writing 1. diphosphorus pentasulfide 2. chlorine trifluoride 3. radium acetate 4. iron (III) hydroxide 5. silver dichromate 6. strontium carbonate 7. lithium bismuthate 8. sodium tetrathionate 9. ammonium molybdate 10. mercury (II) ferricyanide For the exclusive use of UST Engineering students 14 CHEMISTRY APPLICATIONS IN ENGINEERING LABORATORY (ENG 202) Activity1: Formula Naming and Writing DATA SHEET Activity No. 1 FORMULA WRITING AND NAMING Name: _____________________________ Instructor: _______________________ _____________________________ _____________________________ Sec.: _______ Group No.: _________ Date: ___________________________ Practice 1 – Part 1 1 2 3 4 5 6 7 8 9 10 For the exclusive use of UST Engineering students 15 CHEMISTRY APPLICATIONS IN ENGINEERING LABORATORY (ENG 202) Activity 1: Formula Naming and Writing DATA SHEET Activity No. 1 FORMULA WRITING AND NAMING Name: _____________________________ Instructor: _______________________ _____________________________ _____________________________ Sec.: _______ Group No.: _________ Date: ___________________________ Practice 1 – Part 2 1 2 3 4 5 6 7 8 9 10 For the exclusive use of UST Engineering students 16 CHEMISTRY APPLICATIONS IN ENGINEERING LABORATORY (ENG 202) Activity1: Formula Naming and Writing DATA SHEET Activity No. 1 FORMULA WRITING AND NAMING Name: _____________________________ Instructor: _______________________ _____________________________ _____________________________ Sec.: _______ Group No.: _________ Date: ___________________________ Practice 2 Binary Formula for Name of acid Name of sodium salt acid sodium salt HI HF HIO HIO2 HIO3 HIO4 H3AsO4 H3AsO3 HNO3 HNO2 For the exclusive use of UST Engineering students 17 CHEMISTRY APPLICATIONS IN ENGINEERING LABORATORY (ENG 202) Activity 1: Formula Naming and Writing DATA SHEET Activity No. 1 FORMULA WRITING AND NAMING Name: _____________________________ Instructor: _______________________ _____________________________ _____________________________ Sec.: _______ Group No.: _________ Date: ___________________________ Practice 3 – Part 1 Practice 3 – Part 2 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 10 10 For the exclusive use of UST Engineering students 18 CHEMISTRY APPLICATIONS IN ENGINEERING LABORATORY (ENG 202) Activity1: Formula Naming and Writing APPENDIX I. LIST OF COMMON CATIONS Name Formula Other name(s) Aluminum Al+3 Ammonium NH4+ Barium Ba+2 Calcium Ca+2 Chromium (II) Cr+2 Chromous Chromium (III) Cr+3 Chromic Copper (I) Cu+ Cuprous Copper (II) Cu+2 Cupric Iron (II) Fe+2 Ferrous Iron (III) Fe+3 Ferric Hydrogen H+ Hydronium H3O+ Lead (II) Pb+2 Plumbous Lead (IV) Pb+4 Plumbic Lithium Li+ Magnesium Mg+2 Manganese (II) Mn +2 Manganous Manganese (III) Mn +3 Manganic Mercury (I) Hg2+2 Mercurous Mercury (II) Hg+2 Mercuric Nitronium NO2+ For the exclusive use of UST Engineering students 19 CHEMISTRY APPLICATIONS IN ENGINEERING LABORATORY (ENG 202) Activity 1: Formula Naming and Writing Potassium K+ Silver Ag+ Sodium Na+ Strontium Sr+2 Tin (II) Sn +2 Stannous Tin (IV) Sn +4 Stannic Zinc Zn +2 APPENDIX II. LIST OF COMMON ANIONS Anions with -1 Charge: Hydride H- Nitrate NO3- Fluoride F- Nitrite NO2- Chloride Cl- Perchlorate ClO4- Bromide Br- Chlorate ClO3- Iodide I- Chlorite ClO2- Cyanide CN- Hypochlorite OCl- Cyanate OCN- Iodate IO3- Thiocyanate SCN- Bromate BrO3- Hydroxide OH- Hypobromite BrO- Amide NH2- Permanganate MnO4- Acetate CH3COO- Dihydrogen phosphate H2PO4- Formate HCOO- Hydrogen sulfate HSO4- Hydrogen carbonate HCO3- Bismuthate BiO3 - or Bicarbonate For the exclusive use of UST Engineering students 20 CHEMISTRY APPLICATIONS IN ENGINEERING LABORATORY (ENG 202) Activity1: Formula Naming and Writing Anions with -2 Charge: Oxide O2- Hydrogen phosphate HPO42- Sulfide S2- Chromate CrO42- Sulfate SO42- Dichromate Cr2O72- Thiosulfate S2O32- Carbonate CO32- Sulfite SO32- Oxalate C2O42- Peroxide O22- Anions with -3 Charge: Nitride N3- Arsenate AsO43- Phosphate PO43- Arsenite AsO33- APPENDIX III. LIST OF COMMON NAMES FOR CHEMICAL COMPOUNDS Common Name Chemical Name Formula sodium hydrogen carbonate / baking soda NaHCO3 sodium bicarbonate sodium hypochlorite or NaClO bleach (liquid) hydrogen peroxide H2O2 bleach (solid) sodium perborate NaBO3 Borax sodium tetraborate decahydrate Na2B4O7.10 H2O brimstone sulfur S cream of tartar potassium hydrogen tartrate KHC4H4O6 For the exclusive use of UST Engineering students 21 CHEMISTRY APPLICATIONS IN ENGINEERING LABORATORY (ENG 202) Activity 1: Formula Naming and Writing Common Name Chemical Name Formula magnesium sulfate Epsom salt MgSO4.7 H2O heptahydrate Freon dichlorodifluoromethane CF2Cl2 galena lead (II) sulfide PbS grain alcohol ethanol C2 H5OH graphite carbon C gypsum calcium sulfate dihydrate CaSO4.2 H2O hypo sodium thiosulfate Na2S2O3 laughing gas dinitrogen oxide N2 O lime calcium oxide CaO limestone calcium carbonate CaCO3 lye sodium hydroxide NaOH marble calcium carbonate CaCO3 MEK ethyl methyl ketone CH3COC2H5 milk of magnesia magnesium hydroxide Mg(OH)2 muriatic acid hydrochloric acid HCl oil of vitriol sulfuric acid H2SO4 For the exclusive use of UST Engineering students 22 CHEMISTRY APPLICATIONS IN ENGINEERING LABORATORY (ENG 202) Activity1: Formula Naming and Writing Common Name Chemical Name Formula plaster of paris calcium sulfate hemihydrate CaSO4. ½ H2O potash potassium carbonate K2 CO3 iron pyrite (fools gold) iron disulfide FeS2 quartz silicon dioxide SiO2 quicksilver mercury Hg rubbing alcohol isopropyl alcohol (CH3)2CHOH sal ammoniac ammonium chloride NH4Cl salt sodium chloride NaCl salt substitute potassium chloride KCl saltpeter potassium nitrate KNO3 slaked lime calcium hydroxide Ca(OH)2 sugar sucrose C12 H22O11 washing soda sodium carbonate decahydrate Na2CO3.10 H2O wood alcohol methyl alcohol CH3OH For the exclusive use of UST Engineering students