University:
Carleton University
Course:
CHEM 1001 | General Chemistry I
Academic year:

2024
Views:

92

Pages:

2
Author:

ali

Ideal Gas Law Pressure is directly proportional to the number of molecules or moles, as well as temp. Pressure is inversely proportional to volume. PV=nRT P = Pressure V = Volume n = Number of moles R = Gas Constant - 0.0821 L atm/mol K T = Temp. Units: Standard Conditions Standard temp. - 0°C = 273 K Standard molar volume - 1 mole occupies a volume of 22.4 L only at STP Must be in the units you are using Example: If 0.438 moles of Cl gas has a pressure of 5.01 atm and is at 315 K, what is the volume of the gas? PV = nRT V = nRT/P V = (0.438)(0.0821)(315) / 5.01 V = 2.26 L If 11.5 L of O2 is at STP, how much O2 is there? (in moles) PV = nRT n = PV/RT n = (1)(11.5) / (0.0821)(273) n = 0.513 moles O2 Dalton's Law of Partial Pressure Total pressure of a mixture is the sum of the individual pressures of each individual gas. Each individual gas pressure is called partial pressure. Total pressure (Ptotal) is standard pressure (1 atm) if not stated. Must be all the same units - atm/mmHg/torr Example: If oxygen and nitrogen are trapped in a container, O2 = 597 mmHg, N2 = 121 mmHg. What is the pressure of water vapor? Ptotal = P1 + P2 760 mmHg = 597 mmHg + 121 mmHg + PH2O PH2O = 42 mmHg Ideal Gas Equation The state variables (n, P, V, T) are interdependent: If any 3 are known, they can be calculated using the equation of state. For ideal gases (molecules behave independently of each other), the equation of state is the ideal gas equation: PV = nRT State Function When a system changes state, the change in a state function depends only on the difference between the final and initial states. A change of state is defined only by the initial and final states. Process: The series of states along a particular path from A to B Types of Processes Isobaric (constant pressure): Can be used to determine the energy received from adding fuel into a fire. Adiabatic process (no heat transfer): An adiabatic system is divided into two non-interacting parts. Heat: Randomly distributed energy stored in a system. Temperature is the average energy per degree of motion. Heat transfers occur spontaneously from a hot body to a cold one. In molecular terms, heat transfer is the transfer of energy to the surroundings that changes the motions of its atoms or molecules in a chaotic manner. Work: A process whereby a system does work is one that could be used to lift a weight in its surroundings, directly or indirectly. Work is the transfer of energy to the surroundings that changes the motions of atoms/molecules in a uniform (ordered) manner. (may be mechanical, electrical, gravitational, etc.)