intermolecular forces and phase change

what happens at the molecular level during evaporation

in the beginning molecules are moving from liquid to empty space soon the molecules above establish a vapor phase as the concentration of the molecules increase some molecules condense (return to liquid phase) because molecules strike the liquid and are trap due to intermolecular forces. the rate of concentration is given at any given temperature and the rate of condensation increase with increasing connection of molecules in the vapor phase. at a state of dynamic equilibrium (balance forward going same sped as backwards) is reaches a place where the rate of condensation and evaporation are equal

liquid with high intermolecular forces have high or low surface tension and why

high which i think which means more surface tension in addition water has great amount of surface tension due to hydrogen bonding

what is an example of ion-dipole interaction and what is it

hydration

when bonding the hydrogen bonding that is what does it look like

hydrogen in one compound with dotted line to N,O,F bonded or not bonded to hydrogen note it can be like F lone ofr it in a hydrogen compound not FI₃ i think and it in a different compound.

how is ethanol C₂H₃OH or isopropanol C₃H₇OH an example of molar heat of vaporization

if you rub them on your hands the heat in your hands is enough to increase the kinetic energy of the alcohol molecules and evaporate then as a lost of heat your hand feels cold. ethanol C₂H₃OH or isopropanol C₃H₇OH have a lower heat of evaporation then water.

dispersion forces usually increase with what and why

molar mass because molecules with higher molar mass tend to have more electrons ,and dispersion forces increase in strength with the number of electrons further more more electrons means bigger atom which mean the electrons can be easily disturbed because valence or outer electrons are farther away from nucleus

when the temperature higher it mean more kinetic energy thus ................

more molecules can leave the liquid

normal boiling point

normal boiling point of a liquid is the temperature at which it boils when the external pressure is 1 atm

super critical fluid

not a gas not a liquid in between the two

melting point increases as what increase ?

number of electrons increases

clausius clapeyron equation

p=- ΔH,vap/RT + C where R is gas constant and C is a constant it can also take on the linear equation as y=mx + b by measuring the vapor pressure of a liquid at a different temperature and plotting in p versus 1/T we determine the slope which is equal to -ΔHvap/R this method is use to determine heat of evaporation if we know the ΔHvap and P (pressure) of a liquid at one temperature we can use the clausius clapeyron equation we can calculate the vapor pressure of a liquid at different temperatures T₁ and T₂ with P₁/P₂=HΔvap/R(T₁-T₂/T₁T₂)

dipole-induced dipole interaction

polar molecule and an induced dipole

the critical temperature and a substance .................

reflect the strength intermolecular forces high intermolecular forces high critical temperature

for cation what attract or make a stronger ion--dipole interaction

smaller cation, larger charge ex Mg ²⁺ Mg compare to Na⁺ which is larger and has one charge has a grater heat of hydration (the Mg des heat of h greater then Na) mg reacts more strongly with water molecules

why do cation attract dipole more the anions (or have a stong attraction)

the strength of the attraction depends on the charge and size of molecule cation interact more strongly cause in a cation charges are more concentrated cause they are usually smaller then anions.

water boils at what temperature

100c °

Hydrogen bonding

(1) ( strongest) the force of attraction between the hydrogen atom of one molecule and an unshared electron pair on F, O, or N of a neighboring molecule (a special case of dipole-dipole). This is the strongest IMF. Never confuse hydrogen bonding with a bonded hydrogen. The unique physical properties of water are due to the fact that it exhibits hydrogen bonding. As a result of these attractions, water has a high boiling point, high specific heat, and many other unusual properties.

Freezing point and melting point are at what

0c°

whats capillary action

Capillary action can be defined as the ascension of liquids through slim tube, cylinder or permeable substance due to adhesive and cohesive forces interactin

Capillary action

Capillary action describes the spontaneous flow of a liquid into a narrow tube or porous material. Capillary action is caused by the combination cohesive forces of the liquid and the adhesive forces between the liquid and tube material. These forces pull the liquid into the tube. if adhesive forces are stronger than the Cohesion . forces the content or water in tube will be pulled forward.

Evaporation

Definition & Examples. Evaporation is the process of a substance in a liquid state changing to a gaseous state due to an increase in temperature and/or pressure. Evaporation is a fundamental part of the water cycle and is constantly occurring throughout nature.Oct 16, 2014

critical temperature (Tc) (easier definition )

Gases become more difficult to liquefy as the temperature increases because the kinetic energies of the particles that make up the gas also increase. The critical temperature of a substance is the temperature at and above which vapor of the substance cannot be liquefied, no matter how much pressure is applied.putting it in a different way above the critical temperature no dentition between gas and liquid just have fluid

most strong intermolecular force

Hydrogen bonding

Dry ice

Image result for whats dry ice Dry ice, sometimes referred to as "cardice" (chiefly by British chemists), is the solid form of carbon dioxide. It is used primarily as a cooling agent. Its advantages include lower temperature than that of water ice and not leaving any residue (other than incidental frost from moisture in the atmosphere).

ion-dipole forces

Ion-dipole forces are generated between polar water molecules and a sodium ion. The oxygen atom in the water molecule has a slight negative charge and is attracted to the positive sodium ion. These intermolecular ion-dipole forces are much weaker than covalent or ionic bonds. the strength of the attraction depends on the charge and size of molecule cation interact more strongly cause in a cation charges are more concentrated cause they are usually smaller then anions. basically an ion to a dipole

dispersion forces are also called what ?

London forces

Why doesn't CH3F have hydrogen bonding?

Look at the definition of a hydrogen bond: A hydrogen bond is the electromagnetic attractive interaction between polar molecules in which hydrogen (H) is bound to a highly electronegative atom, such as nitrogen (N), oxygen (O) or fluorine (F). The name hydrogen bond is something of a misnomer, as it is not a true bond but a particularly strong dipole-dipole attraction, and should not be confused with a covalent bond. These hydrogen-bond attractions can occur between molecules (intermolecular) or within different parts of a single molecule (intramolecular) In CH3F there is no bond between the H and the F. That is why there is

intermolecular forces vs Intramolecular forces

So now we can define the two forces: Intramolecular forces are the forces that hold atoms together within a molecule. Intermolecular forces are forces that exist between molecules.

dispersion forces

The London dispersion force is the weakest intermolecular force. The London dispersion force is a temporary attractive force that results when the electrons in two adjacent atoms occupy positions that make the atoms form temporary dipoles. This force is sometimes called an induced dipole-induced dipole attraction.

critical pressure Pc

The critical pressure of a substance is the pressure required to liquefy a gas at its critical temperature. Some examples are shown below

Coulomb's law states that:

The magnitude of the electrostatic force of interaction between two point charges is directly proportional to the scalar multiplication of the magnitudes of charges and inversely proportional to the square of the distance between them. eiser definition But you're here to learn about the law. When you have two charged particles, an electric force is created. If you have larger charges, the forces will be larger. If you use those two ideas, and add the fact that charges can attract and repel each other you will understand Coulomb's Law.

can you have negative Kelvin or Celsius

The only scale that doesn't have a negative zone is Kelvin. 0°K represents -273°C. And that's the coldest temperature ever achieved by man. The 0°C represents the point where distilled water freezes. The 100°C represents the point where distilled water boils.

both boiling point and heat of vaporization are determined by what ???

by the strength of intermolecular forces for example Argon and methane which have weak dispersion forces have low boiling points and small molar heat of vaporization . Diethyl ether C₂H₅OC₂H₅ has a dipole moment and the dipole-dipole forces account for it moderetly high boiling and the ΔHvap. both ethanol C₂H₅OH and water have strong hydrogen bonding thus it accounts for there high boiling points and large ΔHvap even benzene a non- polar substances in comparable to that of ethanol due to benzene high polarizability due to the distribution of its electrons in the delocalized pi molecular orbital and the dispersion forces among benzene can be as strong as (or stronger) than dipole-dipole forces and/or hydrogen bond.

what viscosity

a liquid physical property viscosity is the measure of fluid resistance to flow.the greater the viscosity the slower the liquid . the viscosity of liquid usually decrease as temperature increase which mean the hotter the liquid the faster it will move

molar heat of evaporation and boiling point

a measure of force of intermolecular forces ,define as energy which is the the energy required to vaporize one mole of a liquid. molar heat of evaporation is directly related to the intermolecular forces that exist in the liquid if the intermolecular attraction is strong it takes of energy to free the molecules and mar heat evaporation will be high the liquid will also have a low vapor pressure

hydration

basically the breaking of ionic compounds in water

liquid vapor equilibrium

because liquid are denser than gas the collision rate is much higher in the liquid phase than in the gas phase.

gas-liquid

condensation

TEMPERATURE STAY WHAT DURING PHASE CHANGE

constant

the strength of hydrogen bonds depends on ...................

coulombic interaction between lone pairs of electrons of the electronegative atom and the hydrogen nucleus. for example Fluorine is more electronegative than oxygen so then B-P of HF is lower then that of H₂O because each H2O molecule each part of four intermolecular hydrogen bonds thus forces in H₂O stronger then forces HF

a gas can be liquify when the gas is below the critical temperature if you above it your going to the super

critical fluid

gast to solid

deposition

weak hydrogen bonds are a type of

dipole-dipole forces

no-polar molecules what is the only intermolecular forces ?

dispension

The phases that have the most potential energy are

energy are gas liquid solid Same with entropy.

phase change happen when .......

energy is ether lost or gain

boiling point

every liquid has a temperature where they begin to boil.

critical temperature (Tc)

every substances has a critical temperature above which its gas phase cannot be made to liquify, no matter how great the applied pressure is this is also the highest temperature a substances can exist as liquid.

polarizability ables non-polar substances that are gases to condense , how is that possible

ex He the electrons moving around at any moment and uneven placement of charges could create a dipole meant the dipole moment is called an instantaneous dipole because it lasted for a fraction of a second however the atoms does not actually have a dipole because instantaneous dipoles cancel out in He case a instantaneous dipole can create an induce dipole in a neighboring atom at any moment a different instances dipole can create temporary dipoles in the surrounding HE atom this interaction produces dispersion forces , attraction forces that arise as a result of temporary dipoles induced atoms or molecules at very low temperature dispersion forces are strong enough to hold He atoms together causing the gas to condense

liquid to a solid

freezing

what are the IMF in NH₃ and C₆H₆

frist look to see if molecules are polar,non-polar,ion since NH₃ is polar and C₆H₆ is non-polar it is a dipole -induced dipole forces dipole in the name belong to NH₃ and the C₆H₆ is the induced dipole

can CH₃F form a hydrogen bond

from the internet ( not sure how reliable ) it can not , i think they mean in means of the same compound with other molecules because the H is already bonded to the C.

melting is also called

fusion !!!!!

intermolecular forces vs Intramolecular forces which is weaker

generally intermolecular forces take more energy to break bonds in liquid the to turn it into vapor it they are higher boiling point strong intermolecular forces

the density of water is blank then ice

greater

dipole - dipole forces

interaction from polar molecules (molecules that have a dipole moment ) Dipole-Dipole Forces. Dipole-dipole forces are attractive forces between the positive end of one polar molecule and the negative end of another polar molecule. Dipole-dipole forces have strengths that range from 5 kJ to 20 kJ per mole.

surface tension

intermolecular forces pulled liquid down side way but not upwards

what is NOT a van der Waals force

ion-dipole

adhesive

is an attraction between unlike molecules like the glass tube and the water (from Capillary action)

books ( Chang ) definition surface tension

is the amount of energy required to stretch or increase the of a liquid by a unit of area

Cohesion .

is the attractive force between like molecules.

critical pressure Pc books definition

is the minimum pressure that must be applied to bring about a liquefaction at the critical temperature

boiling point

is the temperature at which the vapor pressure of a liquid is equal to to the external pressure. the normal boiling point of a liquid is the temperature at which it boils when the external pressure is 1 atm at the boiling point from within the liquid .when a bubble froms the liquid originally occupying that space is pushes aside and the level of the liquid in the liquid is force to rise . the pressure exserted on the bubbles are largely atmospheric pressure plus some hydrostatic pressure (that is pressure due to the presence of the liquid). the pressure inside the bubbles is due solely o the vapor pressure of the liquid when vapor pressure becomes equal to the internal pressure the bubbles rise to the surface of the liquid and burst. if the vapor pressure were lower than the external pressure the bubbles would collapse before it could rise. we then can concluded that the boiling point of a liquid depends on the external pressure.

water on a waxy substance will do

like an apple a waxy surface will produce little round water beads because a sphere minimize the surface area of a liquid

if your a smaller atom and your electrons are more closer near the nucleus will you have a low or high polarizability

low and has a very low boiling point

solid to liquid

melting

hey for a dipole-dipole interaction the hydrogen bond is pretty ........

strong ... for dipole -dipole interaction

solid directly to a gas

sublimation CO₂ is an example , when you played with it in the spring in hills class the dry ice went straight from a solid to a gas.

Capillary action is an example of what ?

surface tension

vapor pressure increases with .................

temperature

ion-induced dipole interaction

the active interaction between a ion a an induced dipole

what attraction occurs in non-polar substances ?

the charge is distorted by force by the dipole of a polar molecule or ion resulting in a kind a dipole the non-polar molecule is said to be induced because the separation in the non-polar molecule or atom of the positive and negative charges is due to the proximity of a ion or a polar molecule the likely hood of atom non-polar molecule to be induced depends on the ion charge and strength of dipole and the polarizability of the atom or non-polar molecule generally the more electron in a molecule and the more diffuse the electron cloud* is the greater it's polarizability *diffuse cloud means electron cloud that is spread out over a appreciable volume so electrons are Not held tightly by nucleus

the higher the Hvap (molar heat of vaporization )

the higher the boiling point

solid and liquid equilibrium

the melting point of a solid and freezing point of a liquid is the temperature at which both solid and liquid phases coexist in equilibrium

critical temperature and pressure (condensation)

the opposite of evaporation is condensation in principle, a gas can be liquify by either one of the two ways.One way,by cooling a sample of gas we decrease the average kinetic energy of its molecules so that eventually molecules aggregate to form small drops of liquid . or apply pressure to the gas. compression reduces the average distance between so they are held together by mutual attraction.

why does water have a high specific heat

to rise the temperature of water (average kinetic energy) you must first break the many intermolecular hydrogen bonds thus water can absorb a great amount of heat while it temperature only rise a little the converse is also true water can relate a lot of heat and the tempter will not decrease as much.

Liquid boil when the

vapor pressure is equal or more to atmospheric pressure. There cloud up top of mountain because there Less pressure so very cold pressure and temperature are directly related to each other.

equilibrium vapor presssure

vapor pressure measure at dynamic equilibrium between condensation you can just use vapor pressure (same thing)

liquid - gas

vaporization

what one of the most common liquid- solid equilibrium

water at 0°c

more properties of water

water in solid form is less dense unlike other molecules where others solid form is more dense and heavy though many other substances can form intermolecular hydrogen bonds the difference between NH3 and HF is that oxygen atoms can form two hydrogen bonds thus h20 is joined tightly in a 3 dimensional shape in which each oxygen atom is approximately tetrahedrally bonded to four hydrogen two of which are covalent bonds and two in a hydrogen bond

triple point

when all three (sold liquid and gas ) coexist

vapor pressure

when liquid evaporates its gaseous molecules exert pressure

does water have a higher viscosity ?

yes it does because of it ability to form hydrogen bonds