CHEM 120 Final Exam Review (Version 2), CHEM 120: Introduction to General, Organic & Biological Chemistry with Lab, Verified and Correct Answers, Chamberlain College of Nursing.

CHEM 120 Week 8 Final Exam Review
Course Number:CHEM120
Course Title:Introduction to General,Organic & Biological Chemistry with Lab

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CHAPTER 4: GASES
 Pressure is force exerted per unit area. Units: Pascal (Pa) = N/m 2
 Atmospheric pressure: force exerted by atmosphere = m × g, also known as Barometric pressure
 A manometer measures the pressure of a gas with respect to that of the atmosphere, P = d × h × g
 If Pgas > Patm, Pgas = Patm + ΔP. If Pgas < Patm, Pgas = Patm – ΔP
 Boyle’s Law – at constant temperature, the volume decreases as pressure increases V α 1/P
 Charles’s Law – the volume of a fixed amount of an ideal gas at constant pressure is proportional to its
absolute temperature (units in K) V α T, all gases reach zero volume at –273.15°C
 Avogadro’s Principle – the volume occupied by an ideal gas (at given T and P) depends only on the # of
molecules present (not the type), equal # of molecules occupy equal volumes
 The ideal gas equation: PV = nRT
 STP: 273.15K (0°C) and 1 bar, the volume occupied by 1 mol of an ideal gas is 22.7 L
 When a gas is compressed: the molecules are confined in a smaller volume so density increases
 When a gas is heated: increased pressure increases volume occupied by gas so density decreases

Application of Gas Laws
 P1V1 = P2V2
 P1 / T1 = P2 / T2
 V1 / T1 = V2 / T2
 P1V1 / n1T1 = P2V2 / n2T2
 Molar mass: PV = mRT / M M = mRT / PV m = MPV / RT
 Density: d = m / V = nM / V = MP / RT

Gases in Chemical Reactions
 Gases react in volumes proportional to small whole numbers
 Assuming the reactants and products are at the same T & P: volumes are proportional to stoichiometric
coefficients in a chemical equation
 Mole fraction: fraction of molecules that are gas A in a mixture χ A = nA / ntotal, χA + χB = 1
 Partial pressure: nA = PAV/RT nA / ntot = PA / Ptot = χA
 The total pressure of a mixture of gases is the sum of the partial pressures

Kinetic Molecular Theory
 Large particles all following Newtonian motion, separated by a large distance
 The collision between each particle is elastic; total kinetic energy is constant
 Root mean square velocity (urms): close to the average speed of the particles
 Most probable speed (um): highest # of molecules have this speed
 Average speed (uav): average speed of the molecules, little higher than u m

Non-Ideal Gases
 van der Waals equation takes into account intermolecular attraction and excluded volume
 P = (nRT / V-nb) – (n2/v2 a)