HW Chapter 03
Due: 11:59pm on Sunday, February 19, 2017
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A Formula for Formulas
Learning Goal:
To understand the strategy for writing chemical formulas.
Chemistry can be thought of as a language, and, like any language, there are rules that govern usage. In chemistry these rules are particularly strict and
invariant, being governed by the properties of the elements that combine into the chemical words or formulas.
In any chemical formula, the subscripts indicate the number of each type of atom in one molecule or formula unit of the compound. For example, one
molecule of C3 H6 O3 contains three carbon atoms, six hydrogen atoms, and three oxygen atoms. One NF3 molecule contains one nitrogen atom and three
fluorine atoms. One formula unit of Na2 S contains two sodium atoms and one sulfur atom.
There are three main types of chemical formulas: organic, molecular inorganic, and ionic.
1. C3 H6 O3 is an organic compound because it contains predominantly carbon and hydrogen atoms.
2. NF3 is a molecular inorganic compound because it does not contain mainly carbon and it contains only nonmetal atoms.
3. Na2 S is an ionic compound because it is made up of both metal and nonmetal atoms.
Organic compounds
Organic formulas follow the convention of placing C first in the formula, followed by H, followed by the remaining symbols in alphabetical order.
Part A
Which of the following could be the structure of C3 H6 O3 ?
ANSWER:
a
b
c
Part B
Pyridoxine contains 11 hydrogen atoms, 8 carbon atoms, 3 oxygen atoms, and 1 nitrogen atom. What is the chemical formula for pyridoxine?
Express your answer as a chemical formula.
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ANSWER:
Molecular inorganic compounds
Molecular inorganic formulas generally follow the convention of placing elements of groups 13 to 15 first (in that order), followed by the rest of the symbols
starting with those furthest to the left in the periodic table. Elements in the same column are listed alphabetically.
Part C
A certain compound is made up of two fluorine atoms, one chlorine atom, and one phosphorus atom. What is the chemical formula of this compound?
Express your answer as a chemical formula.
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ANSWER:
Ionic compounds
Ionic compounds are always made up of a cation (positive ion) and an anion (negative ion). The cation is always listed first in the formula.
The hard part about writing ionic formulas is determining how many of each ion is needed to make a neutral compound. In Na2 S , the cation is Na+ and the
2−
anion is S . Na forms a cation with a +1 charge because it must lose an electron to achieve 10 electrons like Ne, the nearest noble gas to Na in atomic
number. S forms an anion with a −2 charge because it must gain two electrons to have 18 electrons like Ar, the nearest noble gas to S in atomic number.
2−
and S must now be combined in such a way that the compound is neutral. Two Na+ ions have a total charge of +2 and one S
charge of −2. Therefore, Na2 S is a neutral compound because the total charge sums to zero.
Na
+
2−
ion has a total
Part D
Strontium bromide contains only strontium and bromine. What is the formula for this compound?
Express your answer as a chemical formula.
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ANSWER:
Acid Names
Acids are compounds that have at least one H+ ion that can dissociate from the compound in solution. Precise naming of acids is important because
different acids have very different properties. For example, acetic acid in dilute form is used in cooking (as vinegar), whereas hydrofluoric acid is so toxic that
even splashing a small amount on the skin can be fatal without proper treatment.
Naming binary acids
When naming acids, start by naming the anion. A monatomic anion, such as Cl− , is simple named by replacing the ending of the element name with ide. For
example, Cl− is named chloride and O2− is named oxide.
Once the anion is named, name the acid based on this anion. Start by adding the prefix hydro, and then change the ide suffix to ic. For example, HCl would
require the anion chloride to be changed to chloric. Adding the prefix hydro creates hydrochloric acid.
Part A
What is the name of the acid whose formula is HI?
Spell out the full name of the acid.
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ANSWER:
Naming oxoacids
Oxoacids contain an oxygen atom in the anion. To name them, again, start with the name of the anion when naming acids. Polyatomic anions are named
according to the following rules:
If an element can only form two oxyanions then the one with the least amount of oxygens is given the ending ite. The one containing the most
oxygens is given the ending ate.
Elements that can form four polyatomic oxyanions use prefixes in addition to the ite and ate endings.
−
The oxyanion with the least amount of oxygens is given the prefix hypo and the ending ite (i.e., ClO is hypochlorite).
The oxyanion with the second least amount of oxygens is simply given the ite ending (i.e., ClO2 − is chlorite).
The oxyanion with the second most amount of oxygens is simply given the ate ending (i.e., ClO3 − is chlorate).
Finally, the oxyanion with the most amount of oxygens is given the prefix per and the ending ate (i.e., ClO4 − is perchlorate).
When naming the acid of an oxoanion the endings of the anion are modified as follows:
ate changes to ic (retain prefixes) and
ite changes to ous (retain prefixes).
The word acid is added following the new name of the anion to complete the name of the acid.
Part B
What is the formula for chlorous acid?
Express your answer as a chemical formula.
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ANSWER:
Part C
What is the name of the acid whose formula is H2 CO3 ?
Spell out the full name of the acid.
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ANSWER:
Part D
What is the formula for sulfurous acid?
Express your answer as a chemical formula.
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ANSWER:
Base Names
Many substances with common names are bases (e.g., the strong base sodium hydroxide is commonly known as lye). However, using the systematic names
usually make it straightforward to identify the chemical formula of the base in question. Although there are other definitions of bases, bases can often be
identified by the presence of the hydroxide ion, OH− .
Part A
What is the name of the base that has the formula Ba(OH) ?
What is the name of the base that has the formula Ba(OH)2 ?
Spell out the full name of the compound.
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ANSWER:
Part B
What is the chemical formula for the base sodium hydroxide?
Express your answer as a chemical formula.
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ANSWER:
Part C
Which of these compounds is not a base?
ANSWER:
LiOH
N2 H4
Zn(OH)
2
HBr
Cations and Anions
An atom is made up of a positively­charged nucleus surrounded by negatively­charged electrons. The atom is neutral when there are equal numbers of protons
and electrons. Ions are formed when there are unequal numbers of protons and electrons in an atom. A positive ion is called a cation whereas a negative ion is
called an anion.
Part A
Match each diagram to the atom or ion it represents.
Drag each item to the appropriate bin.
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ANSWER:
Reset
Help
Reset
Help
Part B
What is the charge on the most stable ion of each of the following elements?
Drag each item to the appropriate bin.
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ANSWER:
Mg
1+
2+
Ionic versus Covalent Bonding
3+
Ba
N
O
I
3­
Al
K
S
2­
1­
Chemical bonds are usually classified as either covalent or ionic.
A covalent bond occurs when atoms share electrons. The resulting cluster of atoms is called a molecule, and the compound is considered to be
molecular.
An ionic bond results from a transfer of one or more electrons from one atom to another. This creates oppositely charged ions that group together
into large macroscopic lattices as opposed to small clusters. For this reason, ionic compounds are not considered to be molecular.
As a general rule, covalent bonds occur between two nonmetal atoms whereas ionic bonds occur between a metal and a nonmetal atom.
Part A
Which of the following would you expect to be a molecule and which would you expect to be part of an ionic solid?
Drag the appropriate compounds to their respective bins.
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ANSWER:
Reset
NO
HI
SO
BaO
Molecular
CsF
CsCl
LiI
MgS
Ionic
Part B
Classify the following compounds as having covalent or ionic bonds.
Drag the appropriate compounds to their respective bins.
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ANSWER:
Help
Reset
aluminum chloride
strontium chloride
calcium fluoride
Covalent bonds
nitrogen dioxide
Help
lithium fluoride
sulfur dioxide
Ionic bonds
Covalent Compound Formulas
The chemical formula of covalent compounds can be easily determined from the systematic name of the compound. Greek prefixes are used to indicate the
number of atoms of each element present in the compound.
Number
Prefix
1
mono
Part A
What is the formula for the compound nitrogen monoxide?
Express your answer as a chemical formula.
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ANSWER:
Part B
What is the formula for the compound tetraphosphorus decoxide?
Express your answer as a chemical formula.
2
di
3
tri
4
tetra
5
penta
6
hexa
7
hepta
8
octa
9
nona
10
deca
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ANSWER:
Part C
What is the formula for the compound methane?
Express your answer as a chemical formula.
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ANSWER:
Empirical Formula from Experimental Data
In a student experiment, the empirical formula of a copper halide was found by adding aluminum metal to an aqueous solution of the halide, displacing copper
metal. The copper metal was filtered, washed with distilled water, dried, and weighed; three separate determinations were performed. The copper halide
solution contained 42.62 g of copper chloride per liter. The student recorded the following experimental data.
Trial
Volume of copper chloride solution Mass of filter paper Mass of filter paper with copper
(mL)
(g)
(g)
A
49.6
0.908
1.694
B
48.3
0.922
1.693
C
42.2
0.919
1.588
Part A
Write the empirical formula of copper chloride based on the experimental data.
Express your answer as a chemical formula.
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ANSWER:
Part B
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Formula Mass
The formula mass or formula weight of a substance is determined by summing the atomic masses of each atom in its chemical formula. The formula mass of
a substance is reported in atomic mass units or amu.
Part A
What is the formula mass of Mg(NO3 )2 ?
Express your answer to four significant figures and include the appropriate units.
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ANSWER:
Part B
Calculate the formula mass of ethanol, C2 H5 OH.
Express your answer to three significant figures and include the appropriate units.
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ANSWER:
Ionic Compound Formulas
Many chemical compounds have both common and systematic names. Common names are historical and tend not to identify the elements that make up the
compound. However, the systematic name allows for correct identification of the cations and anions that together make up the ionic compound.
Part A
What is the chemical formula for potassium permanganate?
Express your answer as a chemical formula.
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ANSWER:
Part B
Blue vitriol is commonly used in industrial dyeing processes. What is the chemical formula for blue vitriol, whose systematic name is copper(II) sulfate?
Express your answer as a chemical formula.
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ANSWER:
Part C
Sodium carbonate is used in the manufacture of paper. What is the chemical formula for this compound?
Express your answer as a chemical formula.
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ANSWER:
Ionic Compound Nomenclature and Formulas
Learning Goal:
To learn to write the systematic name of ionic compounds given the chemical formula and to write the chemical formula given the systematic name.
Ionic bonds form when one atom completely transfers one or more electrons to another atom, resulting in the formation of ions. Positively charged ions
(cations) are strongly attracted to negatively charged ions (anions) by electrical forces. All chemical compounds can be named systematically by following a
series of rules. Binary ionic compounds are named by identifying first the positive ion and then the negative ion. Naming compounds with polyatomic ions
involves memorizing the names and formulas of the most common ones.
Part A
Give the systematic name for the compound Mg(NO3 )2 .
Spell out the full name of the compound.
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ANSWER:
Part B
Give the systematic name for the compound Ni2 (SO4 )3 .
Spell out the full name of the compound.
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ANSWER:
Part C
Enter the formula for the compound calcium oxide.
Express your answer as a chemical formula.
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ANSWER:
Part D
Enter the formula for the compound copper(II) phosphate.
Express your answer as a chemical formula.
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ANSWER:
Naming Binary Molecular Compounds
Molecular compounds are usually composed solely of nonmetals. A binary molecular compound is one in which the compound contains only two elements
(regardless of how many atoms are present of each). When naming binary molecular compounds, prefixes are used to specify the number of atoms of each
element. Take a moment to review some of the prefixes shown here.
Prefix Number
mono
one
di
two
tri
three
tetra
four
penta
five
hexa
six
hepta
seven
octa
eight
nona
nine
deca
ten
For example, SF6 is named sulfur hexafluoride. Note that the prefix mono is not used in naming the first element. Also note that the second element in the
name should end with the suffix ide.
Part A
What is the name for the compound NO2 ?
Spell out the full name of the compound.
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ANSWER:
Part B
What is the name for the compound B2 H6 ?
Spell out the full name of the compound.
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ANSWER:
Naming Covalent Compounds
Learning Goal:
To name covalent compounds using the chemical formulas and systematic naming rules.
Many covalent compounds have common names that are not related to their chemical formula. However, systematic names for the compounds can be
determined from the chemical formula of the compound by using an agreed­upon naming conventions.
Naming convention
Example
Name the most electron­poor element first (lower
electronegativity value). This is often the
element farthest to the left in the periodic table.
If the elements are in the same column, use the
bottom one first.
SeO3 (selenium trioxide)
Name the second element using the ide suffix.
Use Greek prefixes to denote the number of
atoms of each element present. However, the
mono prefix is only used when necessary. Drop
the "o" on the prefix if the name begins with an
"a" or "o."
Name elements with oxygen as oxides, except
in case of fluorine.
HCl*
(hydrogen chloride)
N 2 O (dinitrogen monoxide)
SeO3 (selenium trioxide), OF2 (oxygen difluoride)
(water)
(ammonia) PH 3 (phosphine) CH 4 (methane) SiH 4 (silane)
H2 O
Some compounds are always named by their
common name.
NH 3
*Note that HCl(aq) is the acid form of HCl and is called hydrochloric acid.
Part A
What is the name of the covalent compound CCl4 ?
Enter the full name of the compound.
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ANSWER:
Part B
What is the name of the covalent compound N2 O5 ?
Enter the full name of the compound.
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ANSWER:
Naming Ionic Compounds
Learning Goal:
To learn to write the systematic name of ionic compounds given the chemical formula and to write the chemical formula given the systematic name.
Because the common names of many chemical compounds are not helpful in indicating the chemical nature of the compound (e.g., the common name "table
salt" gives no clue that this compound is composed of sodium and chlorine, NaCl), systematic names have been introduced to accurately identify
compounds. The naming of simple ionic compounds is relatively straightforward, once you understand the naming system.
Ionic compounds are named according to their cation first, followed by their anion. Once the cation is named, the anion is then named. The naming
conventions are listed in the tables to the right.
Finally, although ionic compounds need to have an overall neutral charge, the number of cations or anions are not mentioned in the formula name. For
example, AlCl3 is aluminum chloride, not aluminum trichloride.
Cations
Naming convention for cations
If the element forms only one ion, simply
name the element.
Cations that make multiple ions are
distinguished by Roman numerals.
Polyatomic ions have special names.
Example
(potassium)
+
K
Fe
3+
+
NH 4
[iron(III)]
(ammonium)
Anions
Naming convention for anions
If the element forms only one ion, add ide to
the element name.
When there are only two oxoanions in a
series, use ite for the anion with fewer
oxygen atoms and ate for the anion with
more oxygen atoms.
Example
−
Cl
2−
SO
4
Part A
What is the systematic name of Mg(NO3 )2 ?
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ANSWER:
Part B
What is the systematic name of NH4 ClO3 ?
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ANSWER:
Part C
What is the systematic name of PbO?
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ANSWER:
2−
SO
3
−
Halogens and transition metals that can form
up to four oxoanions require distinguishing
prefixes.
(chloride)
(sulfate) (sulfite)
(hypochlorite) −
(chlorite) −
ClO3
(chlorate) −
ClO4
(perchlorate)
ClO
ClO2
Oxidation States
Oxidation states are important for keeping track of electrons in oxidation­reduction reactions. Here are some general rules to remember:
In most cases, oxygen has an oxidation state of −2.
Group 1 and group 2 elements on the periodic table have +1 and +2 oxidation states, respectively.
In most cases, hydrogen has an oxidation state of +1.
Many elements can have more than one oxidation state. In such cases, use the other elements in the compound whose oxidation states are
known to determine the oxidation state of the element that varies.
Neutral compounds
In a neutral compound, the sum of the oxidation states is zero. Note that the sign of the oxidation states and the number of atoms associated with each
oxidation state must be considered. In H2 O, for example, each hydrogen atom has an oxidation state of +1 and each oxygen atom has an oxidation state of −2 for a total of 2(+1) + (−2) = 0.
Part A
What is the oxidation state of an individual bromine atom in NaBrO3 ?
Express the oxidation state numerically (e.g., +1).
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ANSWER:
Part B
What is the oxidation state of an individual nitrogen atom in KNO3 ?
Express the oxidation state numerically (e.g., +1).
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ANSWER:
Ions
In an ion, the sum of the oxidation states is equal to the overall ionic charge. Note that the sign of the oxidation states and the number of atoms associated
−
with each oxidation state must be considered. In OH , for example, the oxygen atom has an oxidation state of −2 and the hydrogen atom has an oxidation
state of +1, for a total of (−2) + (+1) = −1.
Part C
What is the oxidation state of an individual phosphorus atom in PO3 3− ?
Express the oxidation state numerically (e.g., +1).
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ANSWER:
Part D
What is the oxidation state of each individual carbon atom in C2 O4
2−
?
Express the oxidation state numerically (e.g., +1).
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ANSWER:
Percent Composition and Formulas
One of the inherently satisfying features of chemistry is that chemical materials form and interact in a rational and predictable manner. For example, one can
predict a great deal about a particular kind of molecule by experimentally determining the percentage composition of the elements in that compound. This
gives us the relative proportions of the elements in the molecule. For a molecule made up of elements A, B, and C, the proportions might be A : B : C2 ,
meaning that there are two atoms of C for each atom of A and each atom of B. This may not be the actual description of the molecule (which might actually
be A2 B2 C4 ), but it is the "reduced" version of that formula, called the empirical formula. The actual formula is some multiple of the empirical formula. To
know the actual formula we need to know both the empirical formula and the molecular mass of the compound. This provides us with the multiplier value in
whole units that must be applied to the empirical formula to get the actual formula.
A compound is 40.0% C, 6.70% H, and 53.3% O by mass. Assume that we have a 100.­g sample of this compound.
Part A
What are the subscripts in the empirical formula of this compound?
Enter the subscripts for C, H, and O, respectively, separated by commas (e.g., 5,6,7).
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ANSWER:
Part B
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± Using Formula Weights
Alkyl derivatives of mercury are highly toxic and can cause mercury poisoning in humans. Dimethylmercury is one of the strongest known neurotoxins.
Although it is said to have a slightly sweet smell, inhaling enough to discern this would be hazardous.
Part A
Give the empirical formula of dimethylmercury.
Express your answer as a chemical formula.
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ANSWER:
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Part C
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± Counting Atoms using Avogadro's Number
Matter is made up atoms, but in a real chemistry lab, we measure substances in grams. Therefore you need to be able to convert from grams to numbers of
atoms, and vice versa.
Quartz, which contains one silicon atom and two oxygen atoms per formula unit, is the second­most­common mineral on Earth after feldspar. It is used as a
gemstone, as well as in pressure gauges, oscillators, resonators, wave stabilizers, heat­ray lamps, and prismastic lenses, and in the manufacture of glass,
paints, abrasives, and precision instruments such as watches.
Part A
What is the chemical formula for quartz?
Express your answer as a chemical formula.
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ANSWER:
formula for quartz =
Part B
How many oxygen atoms are in 2.00 g of quartz?
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ANSWER:
number of O atoms = ± Empirical Formula by Combustion Analysis
Learning Goal:
To use combustion analysis data to determine an empirical formula
A molecular formula expresses the number of each kind of atom in a molecule. For example, the molecular formula for propene, C3 H6 , indicates three carbon
atoms and six hydrogen atoms per molecule. This also means that one mole of propene contains three moles of carbon and six moles of hydrogen.
An empirical formula expresses the mole ratio of the elements. The empirical formula for propene is CH2 , indicating twice as much hydrogen as carbon.
When analyzing unknown compounds in a lab, it is often possible to identify the mole ratios, and thus the empirical formula, but not the molecular formula.
Notice that the molecular mass of propene, 3(12) + 6(1) = 42 amu, is a multiple of the empirical formula mass, 1(12) + 2(1) = 14 amu .
C H O
An unknown compound contains only carbon, hydrogen, and oxygen (Cx Hy Oz ). Combustion of 4.00 g of this compound produced 5.87 g of carbon dioxide
and 2.40 g of water.
Part A
How many moles of carbon, C, were in the original sample?
Express your answer to three significant figures and include the appropriate units.
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ANSWER:
Part B
How many moles of hydrogen, H, were in the original sample?
Express your answer to three significant figures and include the appropriate units.
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ANSWER:
Part C
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Part D
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Part E
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± Empirical Formula Procedure
Learning Goal:
To understand what an empirical formula is and to learn the procedure for finding empirical formulas.
P O
An empirical formula expresses the simplest ratio of the elements involved. The compound P4 O10 has a P:O ratio of 4:10. However, this ratio can be
simplified to 2:5. Therefore the empirical formula for P4 O10 is P2 O5 .
Another example is hydrogen peroxide, which has the formula H2 O2 and an empirical formula of HO.
One way that chemists analyze new or unknown compounds is to determine the percentage composition of elements experimentally, which yields the
empirical formula.
Part A
What is the empirical formula for the compound P4 O6 ?
Express your answer as a chemical formula.
ANSWER:
Information for Parts B, C, and D
A compound is 80.0% carbon and 20.0% hydrogen by mass. Assume a 100.­g sample of this compound.
Part B
How many grams of each element are in this sample?
Enter the number of grams of carbon followed by the number of grams of hydrogen, separated by a comma (e.g., 30.0,70.0).
ANSWER:
mass of C, mass of H = g Part C
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Part D
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± Hydrates
Hydrates are solid compounds that contain water molecules. When hydrates are heated, the water molecules evaporate, producing the anhydrous form of the
compound.
The formula of a hydrate may be written in two different ways. For example, aluminum chloride hexahydrate can be written as [Al(H2 O)6 ]Cl3 or as AlCl3 ⋅ 6H 2 O. The first formula more accurately shows the bonding arrangement, whereas the second formula makes it easier to see that the anhydrous
form of the compound is aluminum chloride.
Part A
Name the hydrate MgSO4
.
⋅ 7H 2 O
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ANSWER:
Part B
If 37.0 g of MgSO4
is thoroughly heated, what mass of anhydrous magnesium sulfate will remain?
⋅ 7H 2 O
Express your answer to three significant figures and include the appropriate units.
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ANSWER:
± Ionic Compound Analysis
Chemical formulas indicate the ratios of the different types of atoms in a compound. Percentage composition indicates the relative masses of each element in
a compound. Mass ratios are important for lab work, and atomic ratios are important for understanding chemical reactions.
A certain ionic compound is made entirely of aluminum and oxygen.
Part A
What is the formula for this compound?
Express your answer as a chemical formula.
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ANSWER:
Part B
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± Percent Composition
Percent composition refers to the mass percent of each element in a compound:
mass percent =
mass of element
mass of compound
× 100%
For example, the percent composition of water, H2 O, is 11.2% hydrogen and 88.8% oxygen. Therefore, a 100­g sample of water contains 11.2 g of hydrogen
atoms and 88.8 g of oxygen atoms.
The periodic table will be useful when doing this problem. You can access a periodic table by clicking the "Tools" link in the upper right corner of this page.
Part A
A hydrocarbon is a compound that contains mostly carbon and hydrogen. Calculate the percent composition (by mass) of the following hydrocarbon: C 2 H
6 .
Enter the percentages of carbon and hydrogen numerically to four significant figures, separated by commas.
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ANSWER:
carbon, hydrogen = % Part B
A certain metal hydroxide, M(OH)2 , contains 32.8% oxygen by mass. What is the identity of the metal M?
Enter the full name of the element.
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ANSWER:
± The Mass of One Sugar Molecule
Matter is made up of atoms, but in a real chemistry lab, we measure substances in grams. Therefore, you need to be able to convert from atoms to grams,
and vice versa.
Sucrose, the sugar extracted from sugarcane and sugar beets, is an organic compound that contains 12 carbon atoms, 22 hydrogen atoms, and 11 oxygen
atoms per molecule.
Part A
What is the chemical formula for sucrose?
Express your answer as a chemical formula.
ANSWER:
Part B
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Simple Organic Compounds
Organic molecules generally consist of a chain of carbon atoms surrounded by hydrogen atoms or functional groups. The number of carbon atoms in the main
chain is specified by using a prefix, the most common of which are listed in the table.
Prefix Meaning
meth
1
eth
2
prop
3
but
4
pent
5
hex
6
hept
7
oct
8
non
9
A carbon atom will form four bonds to complete its octet, while oxygen will form two bonds and hydrogen will form one bond to complete its duplet.
For this problem, draw all hydrogen atoms explicitly.
Part A
Draw a heptane molecule.
Draw the molecule on the canvas by choosing buttons from the Tools (for bonds), Atoms, and Advanced Template toolbars. The single bond is
active by default. Include all hydrogen atoms.
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ANSWER:
Part B
Draw a molecule of 2­pentanol.
Draw the molecule on the canvas by choosing buttons from the Tools (for bonds), Atoms, and Advanced Template toolbars. The single bond is
active by default. Include all hydrogen atoms.
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ANSWER:
Part C
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Bonding in Electrically Neutral Compounds
Covalent bonding involves the sharing of electrons between atoms. The number of covalent bonds an atom can form relates to the number of electrons it can
share and still result in a neutral molecule. It is important to know how many bonds certain elements are most likely to form in order to draw structural
formulas for molecules.
Part A
How many covalent bonds does carbon form if each of its unpaired electrons participate in one bond?
Express your answer numerically as an integer.
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ANSWER:
Part B
How many covalent bonds does oxygen form if each of its unpaired electrons participate in one bond?
Express your answer numerically as an integer.
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ANSWER:
Part C
How many covalent bonds does nitrogen form if each of its unpaired electrons participate in one bond?
Express the answer numerically as an integer.
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ANSWER:
Part D
How many covalent bonds does hydrogen form if each of its unpaired electrons participate in one bond?
Express your answer numerically as an integer.
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ANSWER:
Exercise 3.2
Give the molecular formulas for the molecules whose ball­and­stick models are given here. Refer to the color scheme in Figure below. Part A
Express your answer as a chemical formula.
ANSWER:
Part B
Express your answer as a chemical formula.
ANSWER:
Part C
Express your answer as a chemical formula.
ANSWER:
Part D
Express your answer as a chemical formula.
ANSWER:
Part E
Express your answer as a chemical formula.
ANSWER:
Exercise 3.4
Give the structural formulas of the molecules shown in figure.
Part A
a
Draw the molecule by placing atoms on the grid and connecting them with bonds. Include all hydrogen atoms.
ANSWER:
Part B
b
Draw the molecule by placing atoms on the grid and connecting them with bonds. Include all hydrogen atoms.
ANSWER:
Part C
c
Draw the molecule by placing atoms on the grid and connecting them with bonds. Include all hydrogen atoms.
ANSWER:
Exercise 3.6
Determine the mass, in grams, of
Part A
7.34 mol N2 O4
ANSWER:
m
= g Part B
3.16×1024 O2 molecules
ANSWER:
m
= g Part C
18.8 mol CuSO4
⋅ 5 H2 O
ANSWER:
m
= g Part D
4.18×1024 molecules of C2 H4 (OH)2
ANSWER:
m
= g Exercise 3.5
Calculate the total number of
Part A
atoms in one molecule of trinitrotoluene (TNT), CH3 C6 H2 (NO2 )3
ANSWER:
N
= atoms Part B
atoms in 1.06×10−3 mol CH3 (CH2 )4 CH2 OH
ANSWER:
N
= atoms Part C
F
mol C HBrClF
atoms in 12.35 mol C2 HBrClF 3
F
Express your answer using four significant figures.
ANSWER:
N
= atoms Exercise 3.8
Determine the number of moles of Br2 in a sample consisting of
Part A
8.12×1022 Br2 molecules
ANSWER:
mol Part B
2.31×1024 Br atoms
ANSWER:
mol Part C
11.6 kg bromine
ANSWER:
mol Part D
2.60 L liquid bromine (d
= 3.10 g/mL
)
ANSWER:
mol Exercise 3.10
Without doing detailed calculations, determine which of the following has the greatest number of S atoms
Part A
1. 0.12 mol of solid sulfur, S8 ;
2. 0.50 mol of gaseous S2 O;
3. 65 g of gaseous SO2 ;
4. 75 mL of liquid thiophene, C4 H4 S(d
ANSWER:
= 1.064 g/mL)
.
a
b
c
d
Exercise 3.12
Determine the mass, in grams, of
Part A
6.50×10−2 mol P4
ANSWER:
m
= g Part B
4.01×1024 molecules of stearic acid, C18 H36 O2
ANSWER:
m
= g Part C
a quantity of the amino acid lysine, C6 H14 N2 O2 , containing 3.01 mol N atoms
ANSWER:
m
= g Exercise 3.16
Explain which of the following statement(s) is (are) correct for sorbic acid, C6 H8 O2 (an inhibitor of mold and yeast).
Part A
1. It has a C : H : O mass ratio of 3:4:1.
2. It has the same mass percent composition as the aquatic herbicide, acrolein, C3 H4 O .
3. It has the same empirical formula as aspidinol, C12 H16 O4 (a drug used to kill parasitic worms).
4. It has four times as many H atoms as O atoms, but four times as much O as H by mass.
Drag the appropriate items to their respective bins.
ANSWER:
Reset
a
True
For the compound Ge[S(CH2 )4 CH3 ]4 , determine:
Part A
the total number of atoms in one formula unit
ANSWER:
= atoms Part B
the ratio, by number, of C atoms to H atoms
ANSWER:
C atoms
H atoms
= Part C
the ratio, by mass, of Ge to S
ANSWER:
mass Ge
mass S
= Part D
the number of g S in 1 mol of the compound
Express your answer using five significant figures.
ANSWER:
c
d
False
Exercise 3.18
N
b
Help
Part E
the number of C atoms in 33.30 g of the compound
Express your answer using four significant figures.
ANSWER:
N
= atoms Exercise 3.20 ­ Enhanced ­ with Feedback
You may want to reference (
page ) Section 3.1 while completing this problem.
Part A
Determine the mass percent O in the mineral azurite, Cu3 (OH)2 (CO3 )2 .
ANSWER:
= %O
% Exercise 3.24
Determine the mass percent of each of the elements in the fungicide copper(II) oleate, Cu(C18 H33 O2 )2 .
Part A
Express your answer using five significant figures.
ANSWER:
= %C
% Part B
Express your answer using five significant figures.
ANSWER:
%H
= % Part C
Express your answer using five significant figures.
ANSWER:
%Cu
= % Part D
Express your answer using five significant figures.
ANSWER:
= %O
% Exercise 3.28
Part A
Without doing detailed calculations, choose which of the following has the greatest mass percent of sulfur: SO2 , S2 Cl 2 , Na2 S, Na2 S2 O3 , or CH3 CH2 SH .
ANSWER:
SO2
Na2 S 2 O3
CH3 CH2 SH
S 2 Cl 2
Na2 S
Exercise 3.34
Determine the empirical formula of
Part A
benzo[a]pyrene, a suspected carcinogen found in cigarette smoke, consisting of 95.21% C and 4.79% H, by mass;
Express your answer as a chemical formula.
ANSWER:
Part B
hexachlorophene, used in germicidal soaps, which consists of 38.37% C, 1.49% H, 52.28% Cl , and 7.86% O by mass.
Express your answer as a chemical formula.
ANSWER:
Exercise 3.38
Adenine, a component of nucleic acids, has the mass percent composition: 44.45% C, 3.73% H, 51.82% N. Its molecular mass is 135.14 u.
Part A
What is its molecular formula?
Express your answer as a chemical formula.
ANSWER:
Exercise 3.44
Para­cresol (p­cresol) is used as a disinfectant and in the manufacture of herbicides. A 0.4039 g sample of this carbon­hydrogen­oxygen compound yields
1.152 g CO2 and 0.2694 g H2 O in combustion analysis. Its molecular mass is 108.1 u . For p­cresol, determine its
Part A
mass percent composition
ANSWER:
= % %C
Part B
ANSWER:
%H
= % Part C
empirical formula
Express your answer as a chemical formula.
ANSWER:
Part D
molecular formula.
Express your answer as a chemical formula.
ANSWER:
Exercise 3.50
Assuming that the complete combustion of ethyl mercaptan, C2 H6 S, (d = 0.84 g/mL ) produces CO2 , H2 O, and SO2 , what masses of each of these
three products would be produced in the complete combustion of 3.05 mL of ethyl mercaptan?
Part A
Express your answer using two significant figures.
ANSWER:
= m(CO2 )
g Part B
Express your answer using two significant figures.
ANSWER:
= m(H 2 O)
g Part C
Express your answer using two significant figures.
ANSWER:
= m(SO2 )
g Exercise 3.52
Indicate the oxidation state of S in
Part A
2−
SO3
Express your answer as a signed oxidation number.
ANSWER:
Part B
2−
S2 O
3
Express your answer as a signed oxidation number.
ANSWER:
Part C
2−
S2 O
8
Express your answer as a signed oxidation number.
ANSWER:
Part D
−
HSO
4
Express your answer as a signed oxidation number.
ANSWER:
Part E
2−
S4 O
6
Express your answer as a signed oxidation number.
ANSWER:
Exercise 3.56
+1
−2
Hydrogen and oxygen usually have oxidation states of +1 and−2,respectively, in their compounds. The following cases serve to remind us that there are
exceptions. What are the oxidation states of the atoms in each of the following compounds?
Part A
MgH
2
Express your answers as a signed integer separated by a comma.
ANSWER:
Mg; H =
Part B
CsO 3
Express your answers as a signed integer separated by a comma.
ANSWER:
Cs; O =
Part C
HOF
Express your answers as a signed integer separated by a comma.
ANSWER:
H; O; F =
Part D
NaAlH4
Express your answers as a signed integer separated by a comma.
ANSWER:
Na; Al; H =
Exercise 3.58
Name these compounds.
Part A
Ba(NO3 )
2
ANSWER:
barium nitrite
barium cyanide
barium nitride
barium nitrate
Part B
HNO 2
ANSWER:
nitrogen acid
hydrogen azide
nitric acid
nitrous acid
Part C
CrO2
ANSWER:
chromium(II) oxide
chromium(IV) oxide
chromium(I) oxide
chromium(II) oxide
Part D
KlO 3
ANSWER:
potassium iodate
potassium iodide
potassium periodate
potassium iodite
Part E
LiCN
ANSWER:
lithium cyanide
lithium cyanate
lithium carbide
lithium nitride
Part F
KIO
ANSWER:
potassium hypoiodite
potassium iodate
potassium iodite
potassium periodate
Part G
Fe(OH)
2
ANSWER:
iron(II) oxide
iron(II) hydroxide
iron(III) hydroxide
iron(III) oxide
Part H
Ca(H 2 PO 4 )
2
ANSWER:
calcium phosphate
calcium hydrogen diphosphate
calcium dihydrogen phosphate
calcium hydrogen phosphate
Part I
H 3 PO 4
ANSWER:
phosphoric base
phosphorous acid
phosphoric acid
methaphosphoric acid
Part J
NaHSO4
ANSWER:
sodium hydrogen sulfate
sodium nitrate
sodium thiosulfate
sodium sulfate
Part K
Na2 Cr2 O7
ANSWER:
sodium dichromate
sodium trichromate
sodium chromate
sodium perchromate
Part L
NH4 C2 H 3 O2
ANSWER:
ammonium formiate
ammonium ozonide
ammonium acrylate
ammonium acetate
Part M
MgC O4
2
ANSWER:
magnesium formiate
magnesium acetate
magnesium oxalate
magnesium oxide
Part N
Na2 C2 O4
ANSWER:
sodium acetate
sodium peroxide
sodium oxalate
sodium hydroxide
Exercise 3.60
Assign suitable names to the compounds
Part A
ICl
ANSWER:
chlorine iodide
iodine chloride
iodine monochloride
chlorine monoiodide
Part B
ClF 3
ANSWER:
fluorine trichloride
chlorine fluoride
fluorine chloride
chlorine trifluoride
Part C
SF4
ANSWER:
sulfur tetrafluoride
sulfur fluoride
fluorine sulfide
fluorine trisulfide
Part D
BrF5
ANSWER:
bromine fluoride
fluorine bromide
fluorine tribromide
bromine pentafluoride
Part E
N 2 O4
ANSWER:
nitrogen oxide
dinitrogen dioxide
dinitrogen oxide
dinitrogen tetroxide
Part F
S4 N4
ANSWER:
tetranitrogen tetrasulfide
sulfur nitride
tetrasulfur tetranitride
tetrasulfur nitride
Exercise 3.62
Write formulas for the compounds:
Part A
magnesium perchlorate
Express your answer as a chemical formula.
ANSWER:
Part B
lead(II) acetate
Express your answer as a chemical formula.
ANSWER:
Part C
tin(IV) oxide
Express your answer as a chemical formula.
ANSWER:
Part D
hydroiodic acid
Express your answer as a chemical formula.
ANSWER:
Part E
chlorous acid
Express your answer as a chemical formula.
ANSWER:
Part F
sodium hydrogen sulfite
Express your answer as a chemical formula.
ANSWER:
Part G
calcium dihydrogen phosphate
Express your answer as a chemical formula.
ANSWER:
Part H
aluminum phosphate
Express your answer as a chemical formula.
ANSWER:
Part I
dinitrogen tetroxide
Express your answer as a chemical formula.
ANSWER:
Part J
disulfur dichloride
Express your answer as a chemical formula.
ANSWER:
Exercise 3.64
Supply the formula for the acids:
Part A
hydrofluoric acid
Express your answer as a chemical formula.
ANSWER:
Part B
nitric acid
Express your answer as a chemical formula.
ANSWER:
Part C
phosphorous acid
Express your answer as a chemical formula.
ANSWER:
Part D
sulfuric acid
Express your answer as a chemical formula.
ANSWER:
Exercise 3.66
Supply the formula for the acids.
Part A
hydrochloric acid
Express your answer as a chemical formula.
ANSWER:
Part B
nitrous acid
Express your answer as a chemical formula.
ANSWER:
Part C
phosphorous acid
Express your answer as a chemical formula.
ANSWER:
Part D
sulfuric acid
Express your answer as a chemical formula.
ANSWER:
Exercise 3.68
Name the following compounds
Part A
KNO2
ANSWER:
potassium nitrate
potassium carbide
potassium nitride
potassium nitrite
Part B
BrF3
ANSWER:
fluorine bromide
bromine difluoride
bromine fluoride
bromine trifluoride
Part C
S 2 Cl 2
ANSWER:
dichlorine disulfide
sulfur chloride
disulfur dichloride
chlorine sulfide
Part D
Mg(ClO)
2
ANSWER:
magnesium hypochlorite
magnesium perchlorate
magnesium chlorate
magnesium chlorite
Part E
Cl 2 O
ANSWER:
chlorine oxide
oxygen dichloride
dichlorine monoxide
dichlorine oxide
Part F
Specify which ones are best described as ionic.
ANSWER:
Cl 2 O
Mg(ClO)
2
S 2 Cl 2
BrF3
KNO2
Exercise 3.74
An 8.442 g sample of Na2 SO4
⋅ xH 2 O
is heated until all the water of hydration is driven off. The resulting anhydrous compound, Na2 SO4 weighs 3.723 g .
Part A
What is the formula of the hydrate?
Express your answer as a chemical formula.
ANSWER:
Exercise 3.76
Part A
Which of the following names is most appropriate for the molecule CH3 (CH2 )2 COOH?
ANSWER:
dimethyleneacetic acid
propanoic acid
butanoic acid
oxobutylalcohol
Exercise 3.75
Part A
Which of the following names is most appropriate for the molecule with the structure shown below? H−
H
H
O
|
|
|
C
−
C
−
C
H
H
−
C
|
|
|
|
|
H
H
H
H
−H
ANSWER:
isopentyl alcohol
2­butanol
butyl alchohol
1­butanol
Exercise 3.78
Part A
Which of the following structures are isomers? Check all that apply.
ANSWER:
a
b
c
d
Exercise 3.80
Write the condensed structural formulas for the organic compounds.
Part A
octane
Express your answer as a chemical formula.
ANSWER:
Part B
heptanoic acid
Express your answer as a chemical formula.
ANSWER:
Part C
3­hexanol
Express your answer as a chemical formula.
ANSWER:
Part D
2­chlorobutane
Express your answer as a chemical formula.
ANSWER:
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