What Is the System Used to Name Chemical Compounds?

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Nomenclature

What is the System Used to Name Chemical Compounds?

Thinking clearly and effectively is the greatest asset of any human being.

Harry Lorayne (1926– )

Engage: Are Scientists Memory Experts? Are You?

A. What do pyrite, iron sulfide, and ferrous sulfide have in common? Explain the similarities and differences among grain alcohol, ethanol, and ethyl alcohol. What are the elemental symbols for silver and gold?

Before Studying this Unit After Studying this Unit

B. Why is CaO named calcium oxide whereas CO is named carbon monoxide? A pyrite crystal. Before Studying this Unit After Studying this Unit

1. Harry Lorayne gained a great deal of notoriety in the 1970s as the world’s foremost memory expert. More than two million copies of his book, The Memory Book, with co- author Jerry Lucas, were sold. A reprint of the book continues to be in print. Mr. Lorayne used his phenomenonal memory to become a best-selling author, magician, entertainer, and lecturer. He is not a scientist.

Most scientists have average memories. Few scientists have ever read Mr. Lorayne’s

book or done any specialized work in improving their memories. Yet the typical chemist knows how to name thousands of chemical compounds. How do chemists know so Harry Lorayne (1926 – ), memory many chemical names? This knowledge is accomplished by learning a system for naming expert. rather than memorization of individual names.

High School Chemistry: An Inquiry Approach

2. Let’s test your short-term memory. You’ll need to work with a partner on this task. Below is a list of the first five hundred digits in pi, the ratio of the circumference to the diameter of a circle.

3.14159265358979323846264338327950288419716939937510582097494459230781640 628620899862803482534211706798214808651328230664709384460955058223172535 940812848111745028410270193852110555964462294895493038196442881097566593 344612847564823378678316527120190914564856692346034861045432664821339360 Pi (π) is the ratio of the circumference 726024914127372458700660631558817488152092096282925409171536436789259036 to the diameter of a circle. The distance around a circle is its 001133053054882046652138414695194151160943305727036575959195309218611738 circumference. The distance across 1932611793105118548074462379962749567351885752724891227938183011949 the circle is its diameter. Choose segments of numbers at random. Read different sequences of numbers to your partner at a steady rate of about one per second. Start with three and work up to four, five, etc., as your partner is able to successfully repeat the sequence backwards to you. Continue until your partner reaches his or her maximum ability. The maximum number of digits that can be repeated backwards is an approximate measure of your short-term memory capacity. Most people can remember between six and eight digits. How many digits can you remember long enough to repeat backwards?

Explore 1: What Symbols are Used to Represent Elements?

3. Jöns Jakob Berzelius was a Swedish physician, scientist, and teacher. In 1807, Berzelius became a chemistry teacher at Sweden’s medical school. He was distressed by having to require his students to memorize a series of astrologically-based symbols that were then used as shorthand for the names of the elements. For example, the symbol for silver was  and gold was . Furthermore, John Dalton proposed a new set of symbols that assigned  to hydrogen. It was a confusing time to be a student of chemistry!

Berzelius decided to introduce a new, simpler system for symbols to represent the elements. To avoid any controversies that could arise from working with any living language, such as English, French, or Spanish, he worked with elemental names in Latin. His system assigned the first letter of the Latin name of the element as the elemental symbol. Where there was more than one element with the same first letter, a Jöns Jacob Berzelius (1779– second letter was used. Thus, hydrogen was symbolized with H, and Helium had the 1848) was a Swedish chemistry symbol He. teacher who first invented a system of letters to represent So do you need to know the Latin names of the elements to know elemental symbols? chemical elements. Yes and no. Fortunately for English speakers, the first letter or two of most elemental names in Latin are the same as in the English word. A few exceptions exist, however, and it helps in learning the symbols if you have some familiarity with the Latin names of those elements.

Unit 7 Nomenclature

Latin Name Symbol English Name Natrium Na Sodium Kalium K Potassium Ferrum Fe Iron Argentum Ag Silver Stannum Sn Tin Hydragyrum Hg Mercury Plumbum Pb Lead

Explain 1 Sodium is a soft, silvery-white solid at room temperature. It is typically 4. Your beginning step in learning the language of chemistry is to learn the equivalent of stored in kerosene or mineral oil to the alphabet. You need to memorize 35 name–symbol pairs for the common elements. keep it from reacting with the You probably already know some symbols, so your personal learning process will oxygen and moisture in the air. Its require you to only work on the symbols of a subset of our list of 35 elements. Cover chemical symbol, Na, is derived from its Latin name natrium. the element columns in the table below and see how many elements you can name.

Z Symbol Element Z Symbol Element 1 H Hydrogen 19 K Potassium 2 He Helium 20 Ca Calcium 3 Li Lithium 24 Cr Chromium 4 Be Beryllium 25 Mn Manganese 5 B Boron 26 Fe Iron 6 C Carbon 27 Co Cobalt 7 N Nitrogen 28 Ni Nickel 8 O Oxygen 29 Cu Copper 9 F Fluorine 30 Zn Zinc 10 Ne Neon 35 Br Bromine 11 Na Sodium 36 Kr Krypton 12 Mg Magnesium 47 Ag Silver 13 Al Aluminum 50 Sn Tin 14 Si Silicon 53 I Iodine 15 P Phosphorus 56 Ba Barium 16 S Sulfur 80 Hg Mercury 17 Cl Chlorine 82 Pb Lead 18 Ar Argon

Learning the symbols of the elements works best if you associate the symbol with its position in the periodic table as you learn it. We’ve provided a partial periodic table below. It has only the atomic number and symbol of the 35 symbols that need to be committed to memory.

Work through our list a few times while looking at nothing but a periodic table. Once you’ve successfully made it through the list on your own, work with a partner, alternating names and symbols in random order, quizzing one another until you are confident you’ve memorized the name–symbol pairs. Then take the quiz that follows.

High School Chemistry: An Inquiry Approach

From Cracolice, M. S., & Peters, E. I. (2011). Introductory Chemistry: An Active Learning Approach. Belmont: CA: Brooks/Cole Cengage Learning.

5. Elemental Symbol Quiz

Instructions: For each name, write the symbol. For each symbol, write the name. Spelling must be correct for credit!

a) mercury

b) P

c) iron

d) F

e) sodium

f) Ag

g) tin

h) K

i) barium

j) Zn

k) nitrogen

l) Cr

Unit 7 Nomenclature

Elaborate 1: What are the Formulas of the Elements?

6. The smallest particle in a sample of most elements is a single atom. The symbol used to represent this particle is the symbol of the element. When we write Fe, for example, that symbol represents an atom of iron.

For some elements, the smallest particle in a sample is a diatomic molecule, a particle that consists of two (di–) atoms chemically bonded to one another. When we write a symbol to represent this particle, it needs to express the diatomic nature of the molecular particle. Thus, the chemical formula of a diatomic molecule is written as H2, for example, where the subscript 2 indicates that two atoms of hydrogen are joined to form a single hydrogen molecule.

7. When 0.045 gram of hydrogen is placed in a balloon at 21°C and 771 mm Hg, the A diatomic molecule is made volume of the gas is 533 mL. Explain how these data indicate that hydrogen gas exists up of two atoms chemically as diatomic molecules. bonded to one another to form a single molecular particle.

8. A total of seven elements exist as diatomic molecules at common temperature and pressure conditions. Each of these elements, therefore, has the formula X2, where X is the symbol of the element. The seven elements are: hydrogen, nitrogen, oxygen, fluorine, chlorine, bromine, and iodine. They are summarized in the illustration below to help you form a connection between the elements and their position in the periodic table.

From Cracolice, M. S., & Peters, E. I. (2011). Introductory Chemistry: An Active Learning Approach. Belmont: CA: Brooks/Cole Cengage Learning.

High School Chemistry: An Inquiry Approach

9. Some elements exist as polyatomic molecules. The prefix poly- means many, and thus polyatomic molecules have many atoms, usually implying more than two. For example, sulfur most commonly exists as a molecule with eight atoms in a ring, S8. However, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S18, S20, and other Sn species have also been isolated and observed! Because of the complexity of polyatomic species, we will assume that all elements other than the seven diatomic species are monatomic (one atom), with the single atom as the smallest particle. We will give you the formula of any polyatomic element, as necessary.

10. Elemental Formula Quiz

Instructions: For each element named, write its formula. For each formula, write the

name. One of the more common of the many molecular forms of sulfur is an a) lithium eight-atom molecule, S8. The cyclic crown-shaped molecule illustrated here is the most common molecular b) O2 structure for sulfur when it is in the solid state. c) nitrogen

d) He

e) hydrogen

f) F2

g) boron

h) C

i) chlorine

j) I2

k) krypton

l) Br2

Unit 7 Nomenclature

Explore 2: When do Chemists Use Prefixes in Names?

11. Compare the names and formulas of the species in each column below, and then answer the questions that follow.

Column 1 Column 2 Name Formula Name Formula dinitrogen pentoxide N2O5 sodium chloride NaCl disilicon hexachloride Si2Cl6 calcium chloride CaCl2 iodine heptafluoride IF7 magnesium sulfide MgS tribromine octoxide Br3O8 aluminum chloride AlCl3 tetraiodine nonoxide I4O9 potassium phosphide K3P disulfur decafluoride S2F10 aluminum oxide Al2O3

12. Compare the Column 1 formulas with the Column 2 formulas. What do they have in common?

13. What do the elements in the Column 1 formulas have in common?

14. What do the elements in the Column 2 formulas have in common?

15. What is different about the elements in the Column 1 and 2 formulas?

16. What is the same about the Columns 1 and 2 names?

17. What is different about the Column 1 and 2 names?

Thinking About Your Thinking Classification

High School Chemistry: An Inquiry Approach

18. The prefixes in the Column 1 names represent the number of atoms of each element in the compound. What number of atoms corresponds to each prefix?

19. In the Column 1 names, how are the endings (suffixes) of the elemental names modified?

20. The Column 2 formulas are made up of ions, which are charged particles that are formed when an atom gains or loses electrons. The net charge on the compound is zero. The charge of a chloride ion, Cl–, is 1–. This indicates that a chlorine atom gains one negatively-charged electron to form a chloride ion. Use the Column 2 formulas to determine the charge on the sodium ion, calcium ion, and aluminum ion.

21. All of the elements in Group 1A form ions with the same charge as the sodium ion. Similarly, all of the elements in Group 2A form ions with the same charge as the calcium ion, and all Group 3A ions have the same charge as the aluminum ion. What are the charges on the sulfide, phosphide, and oxide ions?

22. All Group 5A, 6A, and 7A nonmetal ions have the same charge within each group. What are those charges?

Unit 7 Nomenclature

Explain 2

23. Compounds made from two nonmetal elements located to the right of the stairstep line on the periodic table are called binary molecular compounds. Summarize the rules used to name binary molecular compounds.

24. There are two important exceptions to the rules for naming binary molecular compounds. The official chemical name for H2O is water, and the name of NH3 is ammonia. These non-systematic names are used because the traditional names were well established before a formal naming system became accepted. What would be the systematic name for water?

25. Compounds made from one element from the left of the stairstep line on the periodic table (metals) and one element from the right of the line (nonmetals) are called ionic compounds. Summarize the rules for determining the charges of ions from the position of their parent element in the periodic table.

Ammonia, NH3, is an example of a binary molecular compound because it is made from two elements. The central nitrogen atom is illustrated in blue, and the hydrogen atoms are white.

26. Positively-charged ions are called cations. The name of a cation is the name of the element followed by the word ion. Write the name and formula of two cations from Group 1A and two from Group 2A.

27. Negatively-charge ions are called anions. The name of an anion is the name of the element changed to end in -ide, followed by the word ion. Write the name and formula of two anions from Group 6A and two from Group 7A.

28. Hydrogen is an exception to the rules for naming ions. It can form the hydrogen ion, H+, in some compounds and the hydride ion, H– in others. Which formula, H+ or H–, is the cation? Which formula is the anion?

High School Chemistry: An Inquiry Approach

Elaborate 2: What are the Formulas and Names of Ions Formed from Elements in the B Groups in the Periodic Table?

29. The elements in the B groups of the periodic table are called transition elements. Some transition elements form two or more different ions with different charges. For example, both FeCl2 and FeCl3 exist. To distinguish the compounds, their names must be different, so the name iron chloride is not sufficient. Thus, when an ion has two or more common charges, its charge is included with its name as a Roman numeral in parentheses. The size of the charge is determined by analysis of the anion(s). FeCl2 is iron(II) chloride, and FeCl3 is iron(III) chloride.

30. What is the formula of each of the following?

(a) chromium(II) bromide

(b) chromium(IV) oxide

31. What is the name of each of the following?

(a) Co2S3

(b) CoF4

32. Charge is not included in the names of transition element ions that have only one common charge. The charges on these ions should be committed to memory: CoO is a black powder that has zinc ion Zn2+ been used for centuries as an silver ion Ag+ additive in pottery making. Compounds containing these ions will not have roman numerals in their names.

33. Ionic Compound Quiz I

Instructions: For each element or compound named, write the formula. For each formula, write the name.

a) potassium sulfide

b) NiBr2

c) magnesium nitride

d) CuCl

Unit 7 Nomenclature

Explore 3: How are Many-Atom Ions Named?

34. What patterns exist in the following group of names and formulas?

2– carbonate ion CO3 – nitrate ion NO3 3– phosphate ion PO4 2– sulfate ion SO4 – chlorate ion ClO3

35. Use the relationship among elements in the same group in the periodic table to predict the following names and formulas:

a) nonmetal-oxygen ion name and formula formed with arsenic (Z = 33) as the nonmetal atom (follow the rule for the element directly above arsenic in the periodic table)

b) nonmetal-oxygen ion name and formula formed with selenium (Z = 34) as the nonmetal atom

c) nonmetal-oxygen ion name and formula formed with bromine as the nonmetal atom

High School Chemistry: An Inquiry Approach

Explain 3

36. An ion formed when a group of atoms collectively gains or loses one or more electrons is called a polyatomic ion. The formulas of the five polyatomic ions listed previously should be memorized. Group relationships in the periodic table can be applied to name nonmetal-oxygen polyatomic ions formed by other Group 5A, 6A, and 7A elements.

37. Two additional ions found in common ionic compounds should be committed to memory:

hydroxide ion OH– + ammonium ion NH4

38. Your teacher may require you to learn the names and formulas of other ions. If so, follow his or her advice on how to best accomplish this task.

39. When a polyatomic ion is used more than once in a chemical formula, the entire polyatomic ion is enclosed in parentheses. If it occurs only once in a formula, parentheses are not necessary. For example, sodium nitrate is NaNO3, and magnesium nitrate is Mg(NO3)2.

40. Ionic Compound Quiz II

Instructions: For each element or compound named, write the formula. For each formula, write the name.

a) magnesium hydroxide

b) Fe2(SO4)3

c) calcium phosphate

d) Ba(BrO3)2

e) ammonium nitrate

f) KClO3

g) sodium iodate

h) Ni3(AsO4)2 (As, arsenic, Z = 33)

i) silver tellurate (tellurium, Z = 52) Milk of magnesia is a suspension— a homogenous liquid that contains solid particles—of magnesium j) ZnSeO4 (Se, selenium, Z - = 34) hydroxide in water.

Unit 7 Nomenclature

Elaborate 3: How are the Formula Mass and Molar Mass of Compounds Determined?

41. In Unit 5, we introduced the concepts of atomic mass and molar mass of elements. We can extend this idea to compounds. The equivalent of atomic mass, when applied to a compound, is called formula mass. Formula mass is the sum of the atomic masses in a formula unit. For example, the formula mass of calcium fluoride, CaF2, is: 40.08 u (1 calcium ion) + 2 × 19.00 u (2 fluoride ions) = 78.08 u.

When applied to molecular compounds, the term formula mass is still correct, but chemists usually refer to molecular mass. For example, the molecular (or formula) mass of water, H2O, is: 2 × 1.008 (2 hydrogen atoms) + 16.00 (1 oxygen atom) = 18.02 u.

The concept also extends to molar mass. At with atomic mass, if you change the units of formula or molecular mass to g/mol, you have the molar mass. The mass of one mole of calcium fluoride formula units is 78.08 grams, and the mass of one mole of water molecules is 18.02 grams.

42. Determine the formula or molecular mass of each of the following. Also, state the molar mass of each compound.

a) dinitrogen pentasulfide

b) lithium nitrate

c) carbon tetrafluoride

d) manganese(II) carbonate

e) ammonium sulfate

High School Chemistry: An Inquiry Approach

Explore 4: How is the Percent Composition of a Compound Determined?

43. Your teacher will provide an ionic compound composed of copper(II) cations and unknown anions. Your task in this investigation is to identify the unknown anion. You will do this by extracting pure copper from the salt. The mass of the original compound minus of the mass of the copper gives you the mass of the unknown. Measure 2 g of the ionic compound into a 100-mL beaker, and record the exact mass to the full accuracy of your balance.

44. Add about 50 mL of deionized water to the beaker, being careful not to splash or spill. Use a stirring rod to agitate the solution until all of the solid is dissolved.

45. Zinc reacts with copper(II) ions to form zinc ions and copper metal. You can literally see this reaction progress as the blue-colored copper(II) ion disappears from solution and copper metal forms as a solid. You need to add more than enough zinc to change all of the copper(II) ions to copper. Add 0.9 g of zinc to the solution and stir. Wait until all of the blue color has completely disappeared before proceeding to the next step.

46. The solid at the bottom of your beaker is a mixture of copper and unreacted zinc. Zinc will react with hydrochloric acid to form hydrogen gas and a solution of zinc ions and chloride ions. Copper does not react with hydrochloric acid. Explain what will happen to the solid in your beaker if you add hydrochloric acid.

47. Add 30 mL of 6 M hydrochloric acid solution to your beaker. Stir carefully.

48. Write your initials in pencil on the edge of a piece of filter paper. Determine the mass of the filter paper.

49. Filter and wash the solid copper according to the instructions of your teacher. Dilute the filtrate 10-fold with water before pouring it down the drain.

50. Your teacher will explain how to dry the copper. Record the mass of the solid copper and filter paper when it has dried.

Unit 7 Nomenclature

Explain 4

51. What was the mass of your original ionic compound?

52. What mass of copper was in the original compound?

53. What is the mass of the anion in the original compound?

54. What is the percent copper in the original compound? What is the percent anion?

55. Your original ionic compound was one of these four ionic compounds: copper(II) chloride, copper(II) bromide, copper(II) sulfate, copper(II) nitrate hexahydrate. (A hydrate is an ionic compound that consists of cations, anions, and water molecules. The prefix before the word hydrate indicates the number of water molecules associated with each formula unit of the ionic compound.) Determine the identify of the original compound.

High School Chemistry: An Inquiry Approach

Elaborate 4: How are the Formulas of Compounds Determined?

56. A chemical formula is determined in the same way as all other fundamental chemical knowledge. Experiments are performed in the laboratory, and the data are used to form models. In the specific case of chemical formulas, the percent composition of a compound is determined experimentally. The percent composition is then used to determine the empirical formula of the substance. An empirical formula gives the simplest ratio of atoms of the elements in the compound. Along with experimental data about the formula mass of a compound, the empirical formula leads to the actual formula of the compound. In this exercise, you will determine the empirical formula of a compound.

57. Determine the combined mass of an evaporating dish and watch glass cover.

58. Add 2 g of solid tin granules to the dish and determine the mass of added tin to the limit of accuracy of the balance.

CAUTION! Nitric acid will dissolve 59. In a fume hood, slowly add 5 mL of 8 M nitric acid solution to the dish. Place the watch skin, eyes, etc. Wear glass cover on the dish. Describe the change that occurs. goggles and use common sense when handling this corrosive liquid. 60. When the visible evidence indicates that the chemical change is nearly complete, place the dish and cover on a hot plate. Heat until the contents are nearly dry. If you see and hear spattering, turn down the heat.

61. Follow your teacher’s instructions about transferring the dish and cover to a ring stand and heating the container with a Bunsen burner. Heat until the dish and cover are completely dry. The solid should be yellow and there should be no further brown gas production. Allow the apparatus to cool.

62. Determine the combined mass of the solid, evaporating dish, and watch glass cover.

63. Follow your teacher’s instructions about cleanup.

Unit 7 Nomenclature

64. The final product is an oxide of tin. A tin ion is the cation and the oxide ion is the anion in the resulting ionic compound. The nitrogen in the nitric acid was dissipated into the atmosphere in the form of brown nitrogen dioxide gas. Determine the mass of oxygen in the final compound.

65. Calculate the number of moles of tin and oxygen atoms in your final compound.

66. How does the ratio of moles of tin atoms and moles of oxygen atoms compare with the ratio of number of tin atoms and number of oxygen atoms? Explain.

67. Find the simplest whole-number ratio of tin atoms and oxygen atoms.

68. The simplest whole-number ratio of tin and oxygen atoms gives you the empirical chemical formula of the tin oxide you produced. Write its formula and name.

Explore 5: How are Acids Named?

69. Consider the following list of names and formulas of acids:

Hydrobromic acid HBr Nitric acid HNO3 Sulfuric acid H2SO4 Sulfurous acid H2SO3 Hydrosulfuric acid H2S Hydrochloric acid HCl Phosphorous acid H3PO3 Chloric acid HClO3

High School Chemistry: An Inquiry Approach

What do all of the formulas have in common?

70. Notice the pattern in the prefixes and suffixes of the acid names. Group the acid names according to common prefixes and suffixes. For example, you should list the names and formulas of all of the acids that have names that begin with hydro-. What other groups can you form?

For Questions 71–73, refer to your groupings from Question 70.

71. What pattern is there in the formulas of the acids whose names begin with the prefix hydro-?

72. What pattern is there in the formulas of the acids whose names do not begin with the prefix hydro- and end in the suffix -ic?

73. What is different about acid formulas with names that do not begin with hydro-, as compared to those that do?

74. Consider the following list of acid names and formulas and ion names and formulas:

Hydrobromic acid HBr Bromide ion Br– – Nitric acid HNO3 Nitrate ion NO3 2– Sulfuric acid H2SO4 Sulfate ion SO4 2– Sulfurous acid H2SO3 Sulfite ion SO3 2– Hydrosulfuric acid H2S Sulfide ion S Hydrochloric acid HCl Chloride ion Cl– 3– Phosphorous acid H3PO3 Phosphite ion PO3 – Chloric acid HClO3 Chlorate ion ClO3

What pattern is there in the formulas of ions that are formed by removing all of the H+ from an acid whose name has the prefix hydro- and the suffix -ic?

Unit 7 Nomenclature

75. What pattern is there in the names of the polyatomic ions that are formed by removing all of the H+ from an acid whose name has the suffix -ic?

76. What pattern is there in the names of the polyatomic ions that are formed by removing all of the H+ from an acid whose name has the suffix -ous?

Explain 5

Use the patterns you have described in Questions 71–76 to answer Questions 77–79.

77. How do you name an acid that has a formula with hydrogen and one other nonmetal element? Answer in the form of a rule (or a set of rules) that can be understood by a student who has not studied chemistry.

78. How do you name an acid that has a formula with hydrogen and polyatomic ion whose name has the suffix -ate? Answer in the form of a rule (or a set of rules) that can be understood by a student who has not studied chemistry.

79. How do you name an acid that has a formula with hydrogen and polyatomic ion whose name has the suffix -ite? Answer in the form of a rule (or a set of rules) that can be understood by a student who has not studied chemistry.

80. Use the rules you devised in Questions 77–79 to name the following acids. If you find that your rules need to be changed, revise them as necessary.

H2CO3

HNO2

H3PO4

High School Chemistry: An Inquiry Approach

81. Develop a flow chart that can be used to derive the name of a compound, given its formula.

Thinking About Your Thinking Classification

82. Reconsider Engage Questions A and B. Have you changed your mind about your answers now that you’ve studied this unit?

Homework Questions

What are the Names and Formulas of Chemical Elements and Compounds?

Instructions: You may refer to a clean periodic table while working on all of these questions. In Questions 1–20, for each name, write the formula; for each formula, write the name.

1. Magnesium chloride, aluminum oxide, zinc nitride, lithium sulfide

2. Na2O, AgBr, BaI2, AlN

3. Copper(II) sulfide, iron(III) sulfide, nickel(II) chloride, chromium(III) oxide

4. FeO, Cu2O, CoCl2,PbO2

5. Potassium chlorate, sodium sulfate, potassium phosphate, ammonium nitrate

6. Ag2SO3, Mg3(PO4)2, CaCO3, Zn(NO3)2

7. Copper(II) phosphate, iron(III) sulfite, nickel(II) carbonate, lead(II) nitrate

8. CrPO4, Ni(ClO3)2, PbCO3, Fe2(SO4)3

9. Selenium dioxide, dinitrogen monoxide, phosphorous trichloride, sulfur hexachloride

10. N2O3, PCl5, As2S5, Br2O, SiBr4

Unit 7 Nomenclature

11. Hydrofluoric acid, chloric acid, nitrous acid

12. H2S(aq), H2CO3(aq), H2SO3(aq)

13. Calcium carbonate, ammonium chloride, phosphorous tribromide

14. BaF2, Mn(ClO3)2, OF2

15. Calcium phosphate, cobalt(II) bromide, hydrobromic acid

16. SiO2, Na2O, SO3, (NH4)2SO4

17. Calcium chloride, copper(I) chloride, phosphorous pentabromide

18. SnF2, HNO3(aq), FeSO4

19. Cobalt(II) oxide, mercury(II) iodate, lead(IV) nitrate

20. P4S7, MnCl2, SnO2, HI(aq)

21. Each of the names below were incorrectly written by students on chemistry exams. For each, write a brief note to the student explaining why his or her answer is wrong, and explain how to write the correct name. (a) CaCl2 Calcium dichloride (b) KNO3 Potassium nitride (c) NO Nitrogen oxide (d) Al(ClO3)3 Aluminum trichlorde (e) CuSO4 Copper sulfate (f) Fe2(SO4)3 Iron(II) sulfite (g) SO3 Sulfite ion (h) HIO3 Hydroiodic acid

How is the Percentage Composition of Compounds Calculated and Applied?

22. Determine the percentage composition of: (a) aluminum oxide, (b) manganese(IV) sulfate, (c) silver sulfide, (d) sodium phosphate.

23. Calculate the percentage composition of: (a) nickel(II) chloride, (b) carbon disulfide, (c) zinc nitrate, (d) magnesium bromate.

24. Ammonium nitrate is used as a fertilizer primarily to replenish the nitrogen content of the soil. How many kilograms of ammonium nitrate should be applied to plot that requires 10.0 kg of nitrogen?

25. Steel bolts are often covered with a thin zinc coating. The zinc is applied by a process called electroplating, where zinc ion is changed to zinc metal with electrical energy. The source of zinc metal is a zinc cyanide solution (cyanide ion, CN–). How many grams of zinc cyanide must be used for a process that will plate 50.0 g of zinc?

High School Chemistry: An Inquiry Approach

How are Chemical Formulas Determined?

26. A 100.0-gram sample of a compound composed of iron and sulfur is reduced to pure iron, yielding 54.0 grams of the pure metal. What is the empirical formula of the compound?

27. Determine the empirical formula of a compound composed of 39.12% carbon, 8.772% hydrogen, and 52.11% oxygen. (Hint: Assume that you have a 100-gram sample.)

28. Find the empirical formula of a compound that contains 26.56% potassium, 35.41% chromium, and the remainder oxygen.

29. What is the molecular formula of each of the following? Empirical Formula Molecular Mass (u) (a) CH 78 (b) CH2O 120 (c) P2O3 220

30. A compound is composed of 49.3% carbon, 2.1% hydrogen, and 48.6% chlorine. Its molar mass is 292 g/mol. What is the molecular formula of the compound? (Hint: What is the molar mass of the empirical formula unit? How many empirical formula units are in the molecule?)

31. The molar mass of a compound is 92 g/mol. Analysis of a sample of the compound indicates that it contains 0.606 g of nitrogen and 1.390 g of oxygen. What are its empirical and molecular formulas?

32. The atomic mass of a molecule is 254.1 u. It is composed of 25.24% sulfur, with the balance fluorine. Find the molecular formula and name.