CHM Ch 5

calculate the formula mass of carbon tetrachloride, CCl4

153.8 amu

The compound containing two aluminum atoms to every three oxygen atoms

Al 2 O 3

Explain why CaO is NOT named calcium(II) oxide.

Because calcium forms only one type of ion (Ca2+); therefore, the charge of the ion is not included in the name (it is always the same, 2+).

the compound containing four chlorine atoms to every carbon atom

CCl 4

The compound containing three oxygen atoms to every sulfur atom

SO 3

The compound NCl3 is named nitrogen trichloride, while AlCl3 is simply aluminum chloride. Why the difference?

This question addresses one of the most common errors in nomenclature: the failure to correctly categorize the compound. NCl3 is a molecular compound (two or more nonmetals) and therefore requires prefixes to indicate the number of each type of atom. AlCl3 is an ionic compound (metal and nonmetal) and therefore requires no such prefixes.

How many oxygen atoms are in the chemical formula Fe2(SO4)3? a. 12 b. 2 c. 3 d. 4

a. 12 Subscripts in the formula indicate the number of atoms of each element in the compound. In cases of polyatomic ions enclosed in parentheses, the subscripts inside and outside the parentheses are multiplied to determine the how many atoms are present. Three (SO4) ions contain 3 × 4 or 12 atoms of O.

Determine the formula mass of CCl2F2. a. 120.91 amu b. 108.9 amu c. 66.46 amu d. 132.92 amu

a. 120.91 amu The formula mass of a compound is the sum of the atomic masses of all the elements present. This takes into account both the atomic masses of the elements as well as the subscripts in the formula.

Which formula represents the greatest total number of atoms? a. Al 2(Cr2O7)3 b. Pb(HSO4)4 c. Pb3(PO4)4 d. Al(C2H3O2)3 e. (NH4)3PO4

a. Al2(Cr2O7)3 this formula represent 2 Al atoms + 3(2 Cr atoms + 7 O atoms)=29

Name the compound PF5. a. phosphorus pentafluoride b. phosphorus(III) fluoride c. monophosphorus pentafluoride d. phosphorus fluoride

a. phosphorus pentafluoride The name of a binary molecular compound (containing two nonmetals) consists of four parts. The prefixes indicate the number of atoms present in the formula as indicated by the subscripts. Note: the prefix on the first element is omitted if the subscript is an implied 1 in the formula.

name HC2H3O2

acetic acid the oxyanion is acetate, which ends in -ate

classify each substance as an atomic element, molecular element, molecular compound, or ionic compound krypton

atomic krypton is not listed as diatomic

What is the formula for hydrobromic acid? a. HBrO b. HBr c. HBrO3 d. HBrO2

b. HBr The name (hydrobromic acid) indicates that the acid is binary and consists of hydrogen combined with the nonmetal bromine.

Name the acid H3PO4(aq). a. phosphorus acid b. phosphoric acid c. hydrophosphic acid d. hydrogen phosphate

b. phosphoric acid The name of an oxyacid (one containing oxygen) consists of two parts: the base name for the oxyanion plus the appropriate suffix ("ous" or "ic") and the word "acid."

name each compound BCl3

boron trichloride the name of the compound is the name of the first element, boron, followed by the base name of the second element, chlor, prefixed by tri- to indicate three, and the suffix -ide.

Some metals can form ions of different charges in different compounds. Deduce the charge of the Cr ion in the compound Cr(NO3)3. a. 1+ b. 1- c. 3+ d. 2+

c. 3+ Because the nitrate ion has a charge of 1−, the three nitrate ions together have a charge of 3−. Because the compound must be charge-neutral, Cr must have a charge of 3+.

Carbon tetrachloride has a chlorine-to-carbon mass ratio of 11.8:1. If a sample of carbon tetrachloride contains 35 g of chlorine, what mass of carbon does it contain? a. 11.8 g C b. 3.0 g C c. 0.34 g C d. 1.0 g C

c. 3.0 g C The law of constant composition states, "All samples of a given compound have the same composition by mass". Once mass ratio is known, you can use it as a conversion factor.

Which compound is ionic? a. NI3 b. BrF5 c. MgSO4 d. HNO3

c. MgSO4 An ionic compound in most cases consists of a metal combined with a nonmetal or a polyatomic ion.

which substance has the greatest formula mass? a. O2 b. H2O c. O3 d. H2O2

c. O3

Name the compound CrCl3. a. chromium trichloride b. monochromium trichloride c. chromium(III) chloride d. chromium chloride

c. chromium(III) chloride The name of a binary ionic compound in which the metal forms more than one type of ion consists of three parts

Which element is a molecular element? a. copper b. krypton c. iodine d. potassium

c. iodine A molecular element contains two or more of the same type of atom bonded together to form a molecule. Iodine is a member of the Group 7A elements (halogens), which exist as diatomic molecules.

A compound composed of two elements A and B has a ratio of mass A/ mass B= 3.0 Decomposition of the compound produces 9.0 g of element A. What mass of element B is produced? a. 9.0 g B b. 1.0 g B c. 27.0 g B d. 3.0 g B

d. 3.0 g B the ratio of A/B is 3.0, and A is 9.0 g, so B must be 3.0 g.

Write a chemical formula for a compound that contains two chlorine atoms to every one oxygen atom. a. 2ClO b. ClO2 c. Cl(O2)2 d. Cl20

d. Cl2O Subscripts in the formula indicate the number of atoms of each element in the compound.

What is the formula for manganese(III) oxide? a. MnO b. MnO3 c. Mn3O d. Mn2O3

d. Mn2O3 Use the Roman numeral in the name to determine the charge on the metal cation: (III) indicates 3+. Then combine with the correct number of nonmetal anions, O2─, to form the compound in which the sum of the positive charges equals the sum of the negative charges.

Write a formula for the compound that forms between sodium and chlorite ions. a. NaClO3 b. Na2ClO2 c. Na(ClO)2 d. NaClO2

d. NaClO2 In an ionic compound the total positive charge must equal the total negative change. This takes into account both the charges on the ions as well the number of atoms present.

Write a formula for the compound that forms between Sr and Br. a. Sr2Br b. SrBr c. Sr2Br2 d. SrBr2

d. SrBr2 In an ionic compound the total positive charge must equal the total negative change so that the compound is charge- neutral. This takes into account both the charges on the ions as well the number present.

Name the compound BaSO4. a. barium(II) sulfate b. barium tetrasulfate c. barium monosulfur tetraoxygen d. barium sulfate

d. barium sulfate The name of an ionic compound containing a metal that forms only one type of ion and a polyatomic ion consists of two parts

Name the compound Li3N. a. lithium(I) nitride b. trilithium nitride c. trilithium mononitride d. lithium nitride

d. lithium nitride The name of a binary ionic compound in which the metal forms only one type of ion consists of two parts

give the name of H2S(aq)

hydrosulfuric acid

We just saw that the anion ClO3− is named chlorate. What is the name of the anion IO3−?

iodate

classify each substance as an atomic element, molecular element, molecular compound, or ionic compound KNO3

ionic compound composed of a metal and two nonmetals

classify each substance as an atomic element, molecular element, molecular compound, or ionic compound CoCl2

ionic compound composed of metal (left side of periodic table) and nonmetal (right side of periodic table)

classify each substance as an atomic element, molecular element, molecular compound, or ionic compound SO2

molecular compound two nonmetals

classify each substance as an atomic element, molecular element, molecular compound, or ionic compound nitrogen

molecular element listed as diatomic

name each compound SF6

sulfur hexafluoride the name of the compound is the name of the first element, sulfur, followed by the base name of the second element, fluor, prefixed by hexa- to indicate six, and the suffix -ide.

Name each compound CCl4

Carbon tetrachloride the name of the compound is the name of the first element, carbon, followed by the base name of the second element, chlor, prefixed by tetra- to indicate 4, and the suffix -ide