Gases P2

Significant Figures (SF)

  • All Digits (1-9) are significant

    • Example: 34.2, 4321, 123

  • Zeroes:

    • Between Digits: Significant

    • Leading Zeroes: Not Significant

      • Example: 0.342 (0 not counted)

    • Trailing Zeroes:

      • Without Decimal Point: Not Significant (e.g., 4300)

      • With Decimal Point: Significant (e.g., 4300.00)

Rounding Rules

  • When multiplying/dividing: Round to the least number of significant figures in any measurement.

  • When adding/subtracting: Round to the least accurate decimal place of any measurement.

Pressure Conversions

  • Conversion: Convert between kPa and other units using:

    • Example: Pressure (P) given in kPa.

    • e.g., 580 kPa to 101.3 kPa calculations

Ideal Gas Law

  • Equation: PV = nRT

  • Variables:

    • P = Pressure

    • V = Volume

    • n = Number of moles of gas

    • R = Universal gas constant

    • T = Temperature (Kelvin)

Kinetic Molecular Theory (KMT)

  • Assumptions of KMT:

    • Gas particles are small compared to the container.

    • Particles are in constant random motion.

    • Particles bounce off each other and the walls without loss of energy (elastic collisions).

    • No attractive forces between gas particles.

Real Gas Behavior

  • If KMT holds:

    • Describes ideal gas behavior.

  • Deviations occur under:

    • High Pressure: Particles closer, interactions matter.

    • Low Temperature: Reduced kinetic energy, interactions matter.

Avogadro's Hypothesis

  • Definition: Equal volumes of gases at the same temperature and pressure contain the same number of molecules, regardless of the gas identity.

  • Mole Concept:

    • 1 mole = 6.02 x 10^23 particles (Avogadro's number).

    • Used in stoichiometry calculations.

Vapor Pressure

  • Defined as the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases at a given temperature.

  • Standard Atmospheric Pressure: 101.3 kPa.

  • Relationship:

    • Vapor Pressure increases with temperature until it reaches boiling point.

  • Graph Interpretation:

    • The graph represents the vapor pressure of various liquids against temperature.

Experimental Observations and Procedures

  • Importance of detailed observations during laboratory experiments.

  • Example: Measuring the mass of a mixture, observations during experiments, and interpreting results.