Unit 3: Phases And Phase Changes Flashcards
If you put a sample of 100.0g of Water at 25.0 Degrees Celsius and a sample of 100.0g Water at 90 degrees Celsius, which will freeze first?
The 100g sample of water at 90 degrees Celsius.
What conditions need to be met for a molecule to be polar?
There must be a difference in Electronegativity and arrows leading to a net direction.
Molecules with a net dipole would have _____ IMFs.
Stronger
Define London Dispersion Forces
IMFs w/ molecules that have no net molecular dipole. Instantaneous temporary dipoles are created; the larger the molecules, the stronger the LDFs (easier for the temporary dipoles to form).
What is the difference between Intramolecular and Intermolecular Forces?
Intramolecular is WITHIN
Intermolecular is BETWEEN
Define characteristic of a Gas
Molecules far apart and disordered; negligible interactions occur between the molecules.
Define characteristics of Liquids
Intermediate Situation
Define characteristics of Solids
Molecules are close together and ordered; strong interactions occur between the molecules.
Increase in temperature implies that there is an increase in _____.
Heat Energy
What happens in Melting/Freezing?
Melting is Solid to Liquid and Freezing is Liquid to Solid.
What happens in Boiling/ Condensation?
Liquid to Gas is Boiling and Gas to Liquid is Condensation.
What is the difference between Evaporation and Boiling?
Evaporation typically occurs at the boiling point; molecules escape the gas phase at lower temperatures.
Define Boiling Point
Boiling point is when the vapor pressure is EQUAL TO OR GREATER THAN the atmospheric pressure.
What happens in Sublimation/Deposition?
In sublimation, solid goes to gas; in deposition, gas goes to solid.
What is freeze drying?
Lowering the pressure (vacuum) with water.
Can you always predict the degree of the boiling point based off the present IMFs?
No; the important thing is to be able to recognize trends.
Can hydrogen bonds be considered a chemical bond? What can they be considered?
No, it’s not a chemical bond; it’s an IMF.
A hydrogen bond is an intermolecular force _____ 2 water molecules.
Between
What happens when the hydrogen bond in water is broken?
A physical change occurs.
Why does warmer water freeze faster than colder water?
In the liquid state, there are more disordered molecules; however, considering the disorder, the water molecules are CLOSER to one another than in solid ice. (the unique structure of solid water requires a larger distance in between molecules).
Warmer water will have more disorder, and more distance between molecules; will be easier to form lattice structure which has more distance between molecules.
What are some factors that affect boiling points?
IMFs, Polarity, difference in electronegativity.
Why does the phase change from liquid to gas require so much more heat than the phase change from solid to liquid?
Converting liquid to gas requires the complete breaking of IMFs, whereas converting solid to liquid requires only partial disruption of IMFs.
Heat of fusion entails the _____ of IMFs whereas the heat of vaporization entails the _____ of IMFs.
Partial Disruption- Complete Disruption
Phase Diagrams are a plot of what?
Pressure vs. Temperature (T on the x-Axis and P on the Y-Axis)
