8.1 THERMODYNAMICS

• What are state variables?

  Quantities that describe the state of material
• What does pressure (p) represent?

  Force exerted by material per unit area
• What does volume (V) indicate?

  Amount of space occupied by the material
• How is temperature (T) defined?

  Hotness or coldness of the material
• Why is temperature important in thermodynamics?

  It determines energy exchange as heat
• What does the number of moles (n) represent?

  Amount of substance or constituent particles
• What is the equation relating mass, moles, and molar mass?

  $m_{total} =$$nM$
• What is Boyle's Law?

  $p_1V_1 =$$p_2V_2$
• What does Gay-Lussac's Law state?

  $\frac{p_1}{T_1} =$$\frac{p_2}{T_2}$
• What is Charles's Law?

  $\frac{V_1}{T_1} =$$\frac{V_2}{T_2}$
• What does Avogadro's Law state?

  $\frac{V_1}{n_1} =$$\frac{V_2}{n_2}$
• What is the Ideal Gas Equation?

  $pV =$$nRT$
• What is the value of the gas constant R?

  $R =$$8.314 \frac{J}{mol \cdot K}$
• What is the relationship between liters and cubic meters?

  $1,000 L =$$1 m^3$
• What is the conversion of 1 atm in pascals?

  $1 atm =$$1.013 \times 10^5 Pa$
• What are the properties of an ideal gas?

  • Large number of identical molecules
  • Negligible volume of molecules
  • Obey Newton's Laws
  • Elastic collisions only
• When is the ideal gas equation valid for real gases?

  At very low pressures and high temperatures
• What is the density equation for an ideal gas?

  $\rho_{gas} =$$\frac{pM}{RT}$
• What is Avogadro's number?

  $N_A =$$6.022 \times 10^{23} \text{ molecules/mol}$
• How do you calculate the number of moles?

  $n =$$\frac{m_{total}}{M}$
• What does the kinetic theory of gases assume?

  • Large number of identical particles
  • Molecules behave as point particles
  • Constant motion obeying Newton's laws
  • Perfectly elastic collisions
• What is the average translational kinetic energy of n moles of an ideal gas?

  $K_{tr} =$$\frac{3}{2} nRT$
• What is the root-mean-square speed of gas molecules?

  It varies with temperature and mass
• What does the Maxwell-Boltzmann distribution describe?

  Distribution of molecular speeds in a gas
• What happens when heat is added to a gas?

  It increases the molecular energy of the gas
• What is the formula for heat added to a substance?

  $dQ =$$nC_V dT$
• What is the molar heat capacity at constant volume for a monatomic gas?

  $C_V =$$\frac{3}{2} R$
• How do diatomic and polyatomic gases differ in heat capacity?

  They require additional heat for rotation and vibration
• What is the molar heat capacity for diatomic gases?

  $C_V =$$\frac{5}{2} R$
• What is the molar heat capacity for polyatomic gases?

  Varies, e.g., CO₂ is 28.46 J/mol·K
• What are the types of gases and their heat capacities?

  • Monatomic:
  • He: 12.47 J/mol·K
  • Ar: 12.47 J/mol·K
  • Diatomic:
  • H2: 20.42 J/mol·K
  • N2: 20.76 J/mol·K
  • O2: 21.10 J/mol·K
  • CO: 20.85 J/mol·K
  • Polyatomic:
  • CO2: 28.46 J/mol·K
  • SO2: 31.39 J/mol·K
  • H2S: 25.95 J/mol·K