Chem 2A Final Exam and Already
Solved Solutions 2026 Edition.
law of constant composition - Answer The element mass percent composition of a particular
compound is always the same
law of multiple proportions - Answer if two or more different compounds are composed of
the same two elements, then the ratio of the masses of the second element combined with a
certain mass of the first element is always a ratio of small whole numbers
Atomic number Z - Answer The number of protons in the nucleus of an atom of that element.
Mass number A - Answer A = number of protons + number of neutrons
atomic mass unit - Answer 1 amu = 1/12 the mass of carbon-12 atom
Atomic mass - Answer The atomic mass of an element is the weighted average mass of its
isotopes
molecular mass - Answer By definition the mass of a substance in AMU that corresponds to
the chemical formula of the substance is its molecular mass.
the mole - Answer The number of atoms in exactly 12 grams of carbon-12 is equal to the
mole
avogadro's number - Answer One mole = 6.022 * 10^23 entities, also called avogadro's
number
# of moles = - Answer sample mass / molecular mass
molecular componds - Answer A molecular compound is made up of discrete units called
molecules. Each molecule consists of a certain number of atoms held together with strong
covalent bonds.
ionic network compounds - Answer An ionic network compound is made up of ions forming
strong ionic bonds, forming a crystal. There are no discrete units (molecules)
,atomic network componds - Answer An atomic network compound is made of atoms
covalently bonded to their neighbors throughout the extent of the solid. There are no discrete
units (molecules)
empirical formula - Answer The empirical formula gives the simplest whole number ratio of
atoms of each element in a compound
molecular formula - Answer The molecular formula represents an actual molecule of an
element or compound
ionic unit formula - Answer The ionic unit formula represents the smallest electrically neutral
collection of ions of an ionic network compound
structural formula - Answer The structural formula gives the same information as the
molecular formula, as well as the connectivity of atoms, meaning which atoms are bonded to
which.
condensed structural formula - Answer Line structure. Each meeting point of lines and each
endpoint of the line stands for a carbon atom
Each carbon atom must be surrounded by 4 lines. The number of hydrogen atoms bonded on
each carbon is equal to the number of missing lines around each carbon atom.
oxidation number - Answer The oxidation number of an atom within a molecule or
polyatomic ion is an algebraic number equal to the magnitude of the charge the atom would
have if its shared electrons were held completely by atoms that attract more strongly
rules for calculating oxidation numbers - Answer 1) the ON of a free atom in the gas state is
zero
2) the ON of an atom within a molecule of an element is zero
3) the ON of a monatomic ion surrounded by other ions is equal to the charge of the ion
4) the ON of hydrogen is usually +1
Naming binary ionic compounds - Answer Metal goes first, nonmetal goes second. The name
of metal remains the same, nonmetal takes ending "ide"
Naming binary ionic compounds with a transition metal - Answer Metal goes first, nonmetal
goes second. The name of metal remains the same with charge of metal identified with roman
numeral, nonmetal takes ending "ide"
, Ionic compounds that contain just polyatomic ions - Answer Cation goes first, anion goes
second. Names stay the same
Naming covalent compounds - Answer Name of the first element is the same. The name of
the second takes the ending "IDE" as if it were an anion. Assign prefixes (mono is never used for
the first element).
prefixes - Answer 1 - mono, 2 - di, 3 - tri, 4 - tetra, 5 - penta, 6 - hexa, 7 - hepta, 8 - octa, 9 -
nona, 10 - deca
Naming acids (that do not contain oxygen) - Answer The acid is named with the prefix
"hydro" and the suffix "IC" + acid
Naming acids (that contain oxygen) - Answer 1) if the name of the anion ends in "ate" the
suffix "IC" is added + acid
2) if the name of the anion ends in "ite" the suffix "OUS" is added + acid
hypo-ous , - ous, - ic, per - ic
balancing equations - Answer 1) first balance the element that only occurs in one compound
on each side
2) leave elements that are in two or more formulas unbalanced until just before balancing
hydrogen and oxygen
3) balance in the following order: metals, nonmetals, hydrogen, oxygen
4) balance free elements last
5) balance polyatomic ions or functional groups, unchanged, as a unit
6) use fractional numbers if needed but convert to whole numbers
molarity - Answer M = (moles of a solute) / volume of a solution {mol/L}
V = n/M
M*V=n
Dilution of a solution - Answer since moles of solute initial = moles of solute final:
Mi * Vi = Mf * Vf
Determining the limiting reactant - Answer 1) change grams into moles
2) We need to first find out if they are in stoich ratio (based on moles). If they are not in stoich
ratio then we need to determine which is the limiting reactant
Solved Solutions 2026 Edition.
law of constant composition - Answer The element mass percent composition of a particular
compound is always the same
law of multiple proportions - Answer if two or more different compounds are composed of
the same two elements, then the ratio of the masses of the second element combined with a
certain mass of the first element is always a ratio of small whole numbers
Atomic number Z - Answer The number of protons in the nucleus of an atom of that element.
Mass number A - Answer A = number of protons + number of neutrons
atomic mass unit - Answer 1 amu = 1/12 the mass of carbon-12 atom
Atomic mass - Answer The atomic mass of an element is the weighted average mass of its
isotopes
molecular mass - Answer By definition the mass of a substance in AMU that corresponds to
the chemical formula of the substance is its molecular mass.
the mole - Answer The number of atoms in exactly 12 grams of carbon-12 is equal to the
mole
avogadro's number - Answer One mole = 6.022 * 10^23 entities, also called avogadro's
number
# of moles = - Answer sample mass / molecular mass
molecular componds - Answer A molecular compound is made up of discrete units called
molecules. Each molecule consists of a certain number of atoms held together with strong
covalent bonds.
ionic network compounds - Answer An ionic network compound is made up of ions forming
strong ionic bonds, forming a crystal. There are no discrete units (molecules)
,atomic network componds - Answer An atomic network compound is made of atoms
covalently bonded to their neighbors throughout the extent of the solid. There are no discrete
units (molecules)
empirical formula - Answer The empirical formula gives the simplest whole number ratio of
atoms of each element in a compound
molecular formula - Answer The molecular formula represents an actual molecule of an
element or compound
ionic unit formula - Answer The ionic unit formula represents the smallest electrically neutral
collection of ions of an ionic network compound
structural formula - Answer The structural formula gives the same information as the
molecular formula, as well as the connectivity of atoms, meaning which atoms are bonded to
which.
condensed structural formula - Answer Line structure. Each meeting point of lines and each
endpoint of the line stands for a carbon atom
Each carbon atom must be surrounded by 4 lines. The number of hydrogen atoms bonded on
each carbon is equal to the number of missing lines around each carbon atom.
oxidation number - Answer The oxidation number of an atom within a molecule or
polyatomic ion is an algebraic number equal to the magnitude of the charge the atom would
have if its shared electrons were held completely by atoms that attract more strongly
rules for calculating oxidation numbers - Answer 1) the ON of a free atom in the gas state is
zero
2) the ON of an atom within a molecule of an element is zero
3) the ON of a monatomic ion surrounded by other ions is equal to the charge of the ion
4) the ON of hydrogen is usually +1
Naming binary ionic compounds - Answer Metal goes first, nonmetal goes second. The name
of metal remains the same, nonmetal takes ending "ide"
Naming binary ionic compounds with a transition metal - Answer Metal goes first, nonmetal
goes second. The name of metal remains the same with charge of metal identified with roman
numeral, nonmetal takes ending "ide"
, Ionic compounds that contain just polyatomic ions - Answer Cation goes first, anion goes
second. Names stay the same
Naming covalent compounds - Answer Name of the first element is the same. The name of
the second takes the ending "IDE" as if it were an anion. Assign prefixes (mono is never used for
the first element).
prefixes - Answer 1 - mono, 2 - di, 3 - tri, 4 - tetra, 5 - penta, 6 - hexa, 7 - hepta, 8 - octa, 9 -
nona, 10 - deca
Naming acids (that do not contain oxygen) - Answer The acid is named with the prefix
"hydro" and the suffix "IC" + acid
Naming acids (that contain oxygen) - Answer 1) if the name of the anion ends in "ate" the
suffix "IC" is added + acid
2) if the name of the anion ends in "ite" the suffix "OUS" is added + acid
hypo-ous , - ous, - ic, per - ic
balancing equations - Answer 1) first balance the element that only occurs in one compound
on each side
2) leave elements that are in two or more formulas unbalanced until just before balancing
hydrogen and oxygen
3) balance in the following order: metals, nonmetals, hydrogen, oxygen
4) balance free elements last
5) balance polyatomic ions or functional groups, unchanged, as a unit
6) use fractional numbers if needed but convert to whole numbers
molarity - Answer M = (moles of a solute) / volume of a solution {mol/L}
V = n/M
M*V=n
Dilution of a solution - Answer since moles of solute initial = moles of solute final:
Mi * Vi = Mf * Vf
Determining the limiting reactant - Answer 1) change grams into moles
2) We need to first find out if they are in stoich ratio (based on moles). If they are not in stoich
ratio then we need to determine which is the limiting reactant
