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26 Cards in this Set
- Front
- Back
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Pressure
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pressure = force per unit area
- result of the constant movement of the gas molecules and their collisions with the surfaces around them |
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Properties of a Gas
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p= pressure
v= volume n= moles (same as mass in grams) t= temperature |
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Pressure Laws
1) if P increases then V: 2) if T increases then P: 3) if n increases then P: 4) (all others constant) |
1) decreases (inversely proportional)
2) increases (directly proportional) 3) increases |
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Boyle's Law
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pressure vs volume
P1V1=P2V2 |
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Charles' Law
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volume vs temperature
V1/T1=V2/T2 |
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Avogadro's Law
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volume vs moles
V1/n1=V2/n2 |
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Standard Temp, Pressure & Molar Volume (STP)
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273K
1 atm= 760 torr = 760 mmHg 22.4 L/mol |
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Kinetic Molecular Theory
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1) smaller molecules move faster
2) elasticity: no energy gained or lost 3) particles are much smaller than the distance between them |
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Diffusion
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process of gas molecules spreading out from high concentration to low concentration
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Effusion
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process by which gas molecules escape through a small hole into a vacuum
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Free Path
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the distance a molecule travels between collisions
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Viscosity
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- resistance of fluids to flow
- expressed in units of Poise (1P = 1 g/cm∙s) - usually use cP (centipoise, 100 cP/P) - decreases with increasing T |
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Capillary Action
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- due to IMF between the capillary (polar) and water (also polar) - ADHESION – being greater than IMF between water molecules themselves- COHESION
- result of surface tension |
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Molecular Attraction Forces
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1) Cohesive - intermolecular forces that bind similar molecules to each other (e.g. in surface tension)
2) Adhesive – intermolecular forces that bind a substance to a surface (e.g. in capillary action |
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Meniscuses
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- if liquid in a tube has a strong attraction to the molecules in the confined liquid, concave
- if intermolecular forces are vastly different, convex |
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Intramolecular vs Intramolecular Forces
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intramolecular: holds compounds together (stronger)
intermolecular: holds molecules together - controls physical properties, such as boiling and melting points, vapor pressures, and viscosities |
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Dispersion (μ*-μ*) Intermolecular Force (London)
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- weakest
- make up by strength in numbers - present in all molecules - attractions between an instantaneous dipole and an induced dipole - as number of electrons increases, dispersion forces and boiling point increase |
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Dipole-dipole (μ-μ) Intermolecular Force
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- second to weakest
- occurs in molecules that have permanent dipoles that are attracted to each other (polar) - only important when the molecules are close to each other - the more polar, the higher the boiling point - ex: ethane, formaldehyde |
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Hydrogen bonding (H-X) Intermolecular Force
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- second to strongest
- X= F, O, N atoms - dipoles to an extreme - ex: water, ethanol |
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Ion-dipole (q-μ) Intermolecular Force
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- strongest
- occurs when an ionic compound is mixed with a polar compound - ex: NaCl dissolving in water |
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Surface Tension (𝛾 in mJ/m2)
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- results from the net inward force experienced by the molecules on the surface of a liquid
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Dynamic Equilibrium
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- for a liquid in a closed container eventually an equilibrium is reached
- results in vapor pressure |
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Heat of Vaporizaton
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- amount of heat needed to vaporize a liquid to gas
- endothermic |
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Heat of Condensation
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- amount of heat needed to condense a gas to liquid
- exothermic |
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Boiling Point
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- temperature at which its vapor pressure equals atmospheric pressure (external pressure).
- normal boiling point: boiling point at 760 torr (1 atm) |
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Heat of Fusion
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- heat absorbed upon melting or the heat given off upon freezing
- melting is endothermic - freezing is exothermic |
