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Intermolecular forc*
part 2
Question | Answer |
---|---|
viscosity | resistance of a liquid to flow |
the greater the viscosity the (blank) it flows | the slowly it flows |
how do you measure viscosity | how long a liquid takes to flow out of a pipette under the forces of gravity. How fast an object sings through the liquid. |
what does viscosity measure? | the ease that molecules move past one another |
how are viscosity and T related? | inversely proportional. Viscosity decreases with increasing T. The increasing kinetic energy overcomes the attractive forces and molecules can move easily past each other |
What happen to the molecules in the interior of the liquid? | they experience an attractive force from neighboring molecules which surround on all sides |
what happens to the molecules at the surface of a liquid? | molecules on the surface have neighboring molecules only on one side (the side facing the interior) and thus experience an attractive force whic pull them into the interior |
surface tension | the energy required to increase the surface area of a liquid |
water surface tension at 20 C | 7.29 * 10^ -2 J/m^2 |
cohesive forces | bind molecules of the same type together |
adhesive forces | bind a substance to a surface |
"capillary" action | water move up a thin capillary against the force of gravity |
phase changes | matter in one state changes to another state |
sublimation | solid changes to gas |
melting (fusion) | solid changes to liquid |
freezing | liquid changes to solid |
vaporization | liquid changes to gas |
condensation | gas changes to liquid |
deposition | gas changes to solid |
fusion | the melting process for a solid |
heat of fusion (triangle H sub fus) | the enthalpy change associated with melting a solid |
ice heat of fusion = ? | 6.01 kJ/mol |
heat of vaporization (triangle H sub vap) | heat needed for the vaporization of a liquid |
water heat of vaporization = ? | 40.67 kJ/mol |
true or false: less energy is needed to allow molecules to move past each other than to separate them totally | true |
True or false: great energy is needed to vaporize water than to melt it | true |
specific heat/molar heat capacity | the amount of heat needed to change the T of a substance |
specific heat of ice | 2.09 J/gK |
specific heat of water | 4.18 J/gK |
specific heat of water vapor | 1.84 J/gK |
how can gases be liquified? | by decreasing the T or increasing the P |
Is it easier or harder to use P to liquify gas as T increase? | harder (due to increasing kinetic energy) |
critical temperature | the highest T at which a substance can exist as a liquid |
critical pressure | the pressure required to bring about condensation at the critical T |
is melting, sublimation, and vaporization exothermic or endothermic processes? | endothermic processes |