Chem 1030 - Exam 3 (AUBURN Test
Questions with Complete Answers.
Combustion - Answer specific reaction for the combination of carbon containing species with
O2 to produce CO2 and H2O - release energy
Intermolecular forces
are: - Answer attractive and repulsive forces which occur between two or more molecules;
greater force = molecules stick together more
Rank the following intermolecular forces in order of their strength (least to greatest):
▪Dipole-ion forces
▪Dipole-induced dipole forces
▪London dispersion forces
▪Dipole-dipole forces - Answer London dispersion forces; Dipole-induced dipole forces;
Dipole-dipole forces; Dipole-ion forces
Hydrogen bonding - Answer a specific kind of dipole-dipole interaction where hydrogen
forms a bond with X, where X is an atom with high electronegativity.
London Dispersion Forces (LDF) - Answer intermolecular forces between atoms or non-polar
molecules due to induced dipoles; Strength of induced dipole depends on the polarizability of
the atom/molecule.
Polarizability - Answer ease with which electron cloud can be displaced
Rules for Balancing Equations - Answer 1. Balance the atom which is present in the least
number of molecules (e.g. sulfur)
2. Balance the next atom based on the lowest number of molecules
3. Check to make sure the first atom is still balanced, if not, then rebalance this atom
4. Continue this process until all atoms are balanced
Stoichiometry - Answer Mathematical concept which relates the amount of products to
amount of reactants
Stoichiometry ratio is: - Answer the ratio of molar coefficients for any two molecules in a
chemical reaction
, percent composition - Answer Ratio of the total mass of one element to the total mass of
the substance
Rules to Determine Chemical Formula From Percent Composition - Answer 1. Assume we
have a 100 g sample of element X
2. Determine the mass of each element based on the percentage
3. Determine the moles of each element based on molar mass.
4. Determine the stoichiometric ratio of both elements. This will directly give the empirical
chemical formula of magnetite
Empirical formulas - Answer represent the smallest stoichiometric ratios between elements
in a substance
Molecular formulas - Answer give the exact number of atoms of each element in a
compound
Rules to determine empirical and molecular formulas - Answer 1. Determine empirical
formula based on method for ionic compounds
1a. Convert % to mass based on 100 g sample
1b. Convert mass to moles based on molar mass
1c. Use mole ratio to determine empirical formula
2. Determine how many formula units are needed to equal measured mass
3. Multiple this number by the empirical formula to achieve the molecular formula
Combustion analysis - Answer an experimental procedure which determines that empirical
formula of an unknown molecule based on how much CO2 and H2O are produced
Limiting Reactant - Answer A reactant that is totally consumed during a chemical reaction,
limits the extent of the reaction, and determines the amount of product.
Limiting reactant is determined by: - Answer Moles of reactant
Theoretical yield - Answer the amount of product expected to be produced based on
complete consumption of the limiting reactant
Percent yield - Answer the ratio of the actual yield (based on experiment) with the
theoretical yield
Questions with Complete Answers.
Combustion - Answer specific reaction for the combination of carbon containing species with
O2 to produce CO2 and H2O - release energy
Intermolecular forces
are: - Answer attractive and repulsive forces which occur between two or more molecules;
greater force = molecules stick together more
Rank the following intermolecular forces in order of their strength (least to greatest):
▪Dipole-ion forces
▪Dipole-induced dipole forces
▪London dispersion forces
▪Dipole-dipole forces - Answer London dispersion forces; Dipole-induced dipole forces;
Dipole-dipole forces; Dipole-ion forces
Hydrogen bonding - Answer a specific kind of dipole-dipole interaction where hydrogen
forms a bond with X, where X is an atom with high electronegativity.
London Dispersion Forces (LDF) - Answer intermolecular forces between atoms or non-polar
molecules due to induced dipoles; Strength of induced dipole depends on the polarizability of
the atom/molecule.
Polarizability - Answer ease with which electron cloud can be displaced
Rules for Balancing Equations - Answer 1. Balance the atom which is present in the least
number of molecules (e.g. sulfur)
2. Balance the next atom based on the lowest number of molecules
3. Check to make sure the first atom is still balanced, if not, then rebalance this atom
4. Continue this process until all atoms are balanced
Stoichiometry - Answer Mathematical concept which relates the amount of products to
amount of reactants
Stoichiometry ratio is: - Answer the ratio of molar coefficients for any two molecules in a
chemical reaction
, percent composition - Answer Ratio of the total mass of one element to the total mass of
the substance
Rules to Determine Chemical Formula From Percent Composition - Answer 1. Assume we
have a 100 g sample of element X
2. Determine the mass of each element based on the percentage
3. Determine the moles of each element based on molar mass.
4. Determine the stoichiometric ratio of both elements. This will directly give the empirical
chemical formula of magnetite
Empirical formulas - Answer represent the smallest stoichiometric ratios between elements
in a substance
Molecular formulas - Answer give the exact number of atoms of each element in a
compound
Rules to determine empirical and molecular formulas - Answer 1. Determine empirical
formula based on method for ionic compounds
1a. Convert % to mass based on 100 g sample
1b. Convert mass to moles based on molar mass
1c. Use mole ratio to determine empirical formula
2. Determine how many formula units are needed to equal measured mass
3. Multiple this number by the empirical formula to achieve the molecular formula
Combustion analysis - Answer an experimental procedure which determines that empirical
formula of an unknown molecule based on how much CO2 and H2O are produced
Limiting Reactant - Answer A reactant that is totally consumed during a chemical reaction,
limits the extent of the reaction, and determines the amount of product.
Limiting reactant is determined by: - Answer Moles of reactant
Theoretical yield - Answer the amount of product expected to be produced based on
complete consumption of the limiting reactant
Percent yield - Answer the ratio of the actual yield (based on experiment) with the
theoretical yield
