Department of Chemistry
012 • 4 MAXE
CH College of Natural Sciences & Mathematics
VERITAS ET SCIENTIA
EST. 1869
CHEM 210 — Exam 4
C H A PT E R S 8 & 9 : G A S E S , G A S L A W S & T H E R M O C H E M I ST R Y
INSTITUTION Department of Chemistry EXAM CODE CHEM-210-EX4-2026
PROGRAM CHEM 210 — General Chemistry ACADEMIC YEAR
EXAM TITLE Exam 4 — Gas Laws, Kinetic Molecular TOTAL QUESTIONS 40 Questions
Theory & Thermodynamics
COURSE TITLE General Chemistry / Introductory Organic FORMAT Multiple Choice — Select the Single Best
Chemistry Answer
EXAMINATION INSTRUCTIONS
▸ Select the single best answer for each question.
▸ Questions cover the Ideal Gas Law (PV=nRT), Combined Gas Law, Dalton's Law of Partial Pressures, Graham's Law of Effusion,
gas density, calorimetry, specific heat, enthalpy, Hess's Law, bond energies, and thermodynamic terminology.
▸ Distinguish carefully between exothermic vs. endothermic, effusion vs. diffusion, heat vs. temperature, and initial vs. final
conditions.
▸ Correct answers and detailed rationales appear below each question for comprehensive review.
▸ All content is derived from CHEM 210 Chapters 8–9 curriculum.
SECTION I — GAS LAWS, KINETIC THEORY & THERMOCHEMISTRY Questions 1 – 40
1. What is the Ideal Gas Law?
A. P₁V₁ = P₂V₂
B. PV = nRT
C. V₁/T₁ = V₂/T₂
D. Ptotal = P₁ + P₂ + P₃
CORRECT ANSWER B — PV = nRT
RATIONALE The Ideal Gas Law (PV = nRT) relates pressure (P), volume (V), number of moles (n), the gas constant (R =
0.0821 L·atm/mol·K), and absolute temperature (T in Kelvin). It combines Boyle's, Charles's, and Avogadro's
laws into a single equation. Option A is Boyle's Law (constant T, n). Option C is Charles's Law (constant P, n).
Option D is Dalton's Law of Partial Pressures.
, 2. What unit must temperature ALWAYS be in for gas law calculations?
A. Celsius (°C)
B. Fahrenheit (°F)
C. Kelvin (K)
D. Any temperature unit works as long as it's consistent
CORRECT ANSWER C — Kelvin (K)
RATIONALE All gas law calculations require absolute temperature in Kelvin because gas volume is directly proportional to
absolute temperature (Charles's Law). Using Celsius or Fahrenheit would produce incorrect results — at 0°C,
the volume is not zero; only at 0 K (absolute zero) would volume theoretically be zero. K = °C + 273.15
(commonly rounded to +273).
3. What is the value of the gas constant R (in L·atm/mol·K)?
A. 8.314
B. 0.0821
C. 62.36
D. 1.987
CORRECT ANSWER B — 0.0821 L·atm/mol·K
RATIONALE R = 0.0821 L·atm/mol·K when pressure is in atmospheres and volume is in liters. The value of R depends on
the units used: 8.314 J/mol·K (Option A, SI units), 62.36 L·torr/mol·K (Option C), 1.987 cal/mol·K (Option D).
Always match the R value to the units in the problem. The most common value in general chemistry is 0.0821
L·atm/mol·K.
4. How do you convert degrees Celsius to Kelvin?
A. Subtract 273
B. Add 273
C. Multiply by 9/5 and add 32
D. Divide by 273
CORRECT ANSWER B — Add 273
RATIONALE Kelvin = Celsius + 273.15 (commonly rounded to +273). The Kelvin scale is an absolute temperature scale
where 0 K = –273.15°C (absolute zero). For most general chemistry calculations, adding 273 provides sufficient
accuracy. Example: 25°C + 273 = 298 K. Option A converts K → °C. Option C converts °C → °F.
5. What is the formula for gas density?
A. d = m/V
B. d = PM/RT
C. d = n/V
D. d = RT/PM
CORRECT ANSWER B — d = PM/RT
RATIONALE Gas density is derived from the Ideal Gas Law: PV = nRT → PV = (m/M)RT → d = m/V = PM/RT, where P =
pressure, M = molar mass, R = gas constant, T = temperature (K). This formula shows that gas density
increases with pressure and molar mass, and decreases with temperature. Option A is the general density
formula (not specific to gases).
012 • 4 MAXE
CH College of Natural Sciences & Mathematics
VERITAS ET SCIENTIA
EST. 1869
CHEM 210 — Exam 4
C H A PT E R S 8 & 9 : G A S E S , G A S L A W S & T H E R M O C H E M I ST R Y
INSTITUTION Department of Chemistry EXAM CODE CHEM-210-EX4-2026
PROGRAM CHEM 210 — General Chemistry ACADEMIC YEAR
EXAM TITLE Exam 4 — Gas Laws, Kinetic Molecular TOTAL QUESTIONS 40 Questions
Theory & Thermodynamics
COURSE TITLE General Chemistry / Introductory Organic FORMAT Multiple Choice — Select the Single Best
Chemistry Answer
EXAMINATION INSTRUCTIONS
▸ Select the single best answer for each question.
▸ Questions cover the Ideal Gas Law (PV=nRT), Combined Gas Law, Dalton's Law of Partial Pressures, Graham's Law of Effusion,
gas density, calorimetry, specific heat, enthalpy, Hess's Law, bond energies, and thermodynamic terminology.
▸ Distinguish carefully between exothermic vs. endothermic, effusion vs. diffusion, heat vs. temperature, and initial vs. final
conditions.
▸ Correct answers and detailed rationales appear below each question for comprehensive review.
▸ All content is derived from CHEM 210 Chapters 8–9 curriculum.
SECTION I — GAS LAWS, KINETIC THEORY & THERMOCHEMISTRY Questions 1 – 40
1. What is the Ideal Gas Law?
A. P₁V₁ = P₂V₂
B. PV = nRT
C. V₁/T₁ = V₂/T₂
D. Ptotal = P₁ + P₂ + P₃
CORRECT ANSWER B — PV = nRT
RATIONALE The Ideal Gas Law (PV = nRT) relates pressure (P), volume (V), number of moles (n), the gas constant (R =
0.0821 L·atm/mol·K), and absolute temperature (T in Kelvin). It combines Boyle's, Charles's, and Avogadro's
laws into a single equation. Option A is Boyle's Law (constant T, n). Option C is Charles's Law (constant P, n).
Option D is Dalton's Law of Partial Pressures.
, 2. What unit must temperature ALWAYS be in for gas law calculations?
A. Celsius (°C)
B. Fahrenheit (°F)
C. Kelvin (K)
D. Any temperature unit works as long as it's consistent
CORRECT ANSWER C — Kelvin (K)
RATIONALE All gas law calculations require absolute temperature in Kelvin because gas volume is directly proportional to
absolute temperature (Charles's Law). Using Celsius or Fahrenheit would produce incorrect results — at 0°C,
the volume is not zero; only at 0 K (absolute zero) would volume theoretically be zero. K = °C + 273.15
(commonly rounded to +273).
3. What is the value of the gas constant R (in L·atm/mol·K)?
A. 8.314
B. 0.0821
C. 62.36
D. 1.987
CORRECT ANSWER B — 0.0821 L·atm/mol·K
RATIONALE R = 0.0821 L·atm/mol·K when pressure is in atmospheres and volume is in liters. The value of R depends on
the units used: 8.314 J/mol·K (Option A, SI units), 62.36 L·torr/mol·K (Option C), 1.987 cal/mol·K (Option D).
Always match the R value to the units in the problem. The most common value in general chemistry is 0.0821
L·atm/mol·K.
4. How do you convert degrees Celsius to Kelvin?
A. Subtract 273
B. Add 273
C. Multiply by 9/5 and add 32
D. Divide by 273
CORRECT ANSWER B — Add 273
RATIONALE Kelvin = Celsius + 273.15 (commonly rounded to +273). The Kelvin scale is an absolute temperature scale
where 0 K = –273.15°C (absolute zero). For most general chemistry calculations, adding 273 provides sufficient
accuracy. Example: 25°C + 273 = 298 K. Option A converts K → °C. Option C converts °C → °F.
5. What is the formula for gas density?
A. d = m/V
B. d = PM/RT
C. d = n/V
D. d = RT/PM
CORRECT ANSWER B — d = PM/RT
RATIONALE Gas density is derived from the Ideal Gas Law: PV = nRT → PV = (m/M)RT → d = m/V = PM/RT, where P =
pressure, M = molar mass, R = gas constant, T = temperature (K). This formula shows that gas density
increases with pressure and molar mass, and decreases with temperature. Option A is the general density
formula (not specific to gases).
