GENERAL CHEMISTRY THE ESSENTIAL
CONCEPTS RAYMOND CHANG CONCEPT
REVIEW GUIDE 2026 CHEMICAL BONDING
AND MOLECULAR STRUCTURE
◉ What are the rules for significant figures? Answer: 1. Zeros
between nonzero digits are significant. 2. Leading zeros are not
significant. 3. Trailing zeros are significant only if there is a decimal.
◉ What is the mole in chemistry? Answer: A unit that represents
6.022 x 10^23 particles of a substance.
◉ How do you calculate the number of moles from grams? Answer:
Divide the mass of the substance by its molar mass.
◉ What is the formula for percent error? Answer: Percent Error =
|(Experimental Value - Theoretical Value)| / Theoretical Value x 100.
◉ What is the density formula? Answer: Density = Mass / Volume.
◉ How do you convert between units using dimensional analysis?
Answer: Multiply by conversion factors that cancel out the unwanted
units.
,◉ What is the empirical formula of a compound with 17.3% H and
82.7% C? Answer: CH2.
◉ What is the molecular formula of a compound with an empirical
formula of CH2 and a molar mass of 84 g/mol? Answer: C6H12.
◉ What is the empirical formula for a compound with 12 carbon
atoms, 14 hydrogen atoms, and 6 oxygen atoms? Answer: C2H3O.
◉ What is the balanced equation for the combustion of methane
(CH4)? Answer: CH4 + 2O2 → CO2 + 2H2O.
◉ What is the empirical formula of a compound that contains 12.1%
C, 16.2% O, and 71.7% Cl? Answer: COCl2.
◉ How do you balance a chemical equation? Answer: Adjust the
coefficients to ensure the same number of each type of atom on both
sides.
◉ What is the significance of the molecular weight? Answer: It helps
in calculating the number of moles and understanding the
composition of compounds.
, ◉ What is the formula for calculating the number of oxygen atoms in
a compound? Answer: Multiply the number of moles of the
compound by the number of oxygen atoms in its formula.
◉ What is the molar mass of copper (Cu)? Answer: 63.5 g/mol
◉ Which ore contains the highest percentage of copper by mass?
Answer: Chalcocite, Cu2S (159 g/mol)
◉ How do you calculate the percentage of gold (Au) in an ore sample
that produced AuCl3? Answer: Use the formula: (mass of Au in AuCl3
/ mass of ore sample) × 100%
◉ What is the molar mass of AuCl3? Answer: 303 g/mol
◉ How many moles of C2H6 are needed to produce 22 moles of
CO2? Answer: The balanced equation shows that 2 moles of C2H6
produce 4 moles of CO2, so 11 moles of C2H6 are needed.
◉ How many grams of CO2 are produced from the complete
combustion of 0.25 mol of butane (C4H10)? Answer: 22 g (using the
molar mass of CO2, 44.01 g/mol)
CONCEPTS RAYMOND CHANG CONCEPT
REVIEW GUIDE 2026 CHEMICAL BONDING
AND MOLECULAR STRUCTURE
◉ What are the rules for significant figures? Answer: 1. Zeros
between nonzero digits are significant. 2. Leading zeros are not
significant. 3. Trailing zeros are significant only if there is a decimal.
◉ What is the mole in chemistry? Answer: A unit that represents
6.022 x 10^23 particles of a substance.
◉ How do you calculate the number of moles from grams? Answer:
Divide the mass of the substance by its molar mass.
◉ What is the formula for percent error? Answer: Percent Error =
|(Experimental Value - Theoretical Value)| / Theoretical Value x 100.
◉ What is the density formula? Answer: Density = Mass / Volume.
◉ How do you convert between units using dimensional analysis?
Answer: Multiply by conversion factors that cancel out the unwanted
units.
,◉ What is the empirical formula of a compound with 17.3% H and
82.7% C? Answer: CH2.
◉ What is the molecular formula of a compound with an empirical
formula of CH2 and a molar mass of 84 g/mol? Answer: C6H12.
◉ What is the empirical formula for a compound with 12 carbon
atoms, 14 hydrogen atoms, and 6 oxygen atoms? Answer: C2H3O.
◉ What is the balanced equation for the combustion of methane
(CH4)? Answer: CH4 + 2O2 → CO2 + 2H2O.
◉ What is the empirical formula of a compound that contains 12.1%
C, 16.2% O, and 71.7% Cl? Answer: COCl2.
◉ How do you balance a chemical equation? Answer: Adjust the
coefficients to ensure the same number of each type of atom on both
sides.
◉ What is the significance of the molecular weight? Answer: It helps
in calculating the number of moles and understanding the
composition of compounds.
, ◉ What is the formula for calculating the number of oxygen atoms in
a compound? Answer: Multiply the number of moles of the
compound by the number of oxygen atoms in its formula.
◉ What is the molar mass of copper (Cu)? Answer: 63.5 g/mol
◉ Which ore contains the highest percentage of copper by mass?
Answer: Chalcocite, Cu2S (159 g/mol)
◉ How do you calculate the percentage of gold (Au) in an ore sample
that produced AuCl3? Answer: Use the formula: (mass of Au in AuCl3
/ mass of ore sample) × 100%
◉ What is the molar mass of AuCl3? Answer: 303 g/mol
◉ How many moles of C2H6 are needed to produce 22 moles of
CO2? Answer: The balanced equation shows that 2 moles of C2H6
produce 4 moles of CO2, so 11 moles of C2H6 are needed.
◉ How many grams of CO2 are produced from the complete
combustion of 0.25 mol of butane (C4H10)? Answer: 22 g (using the
molar mass of CO2, 44.01 g/mol)
