APCHEM- unit 5 active recall

How do you find faherinet from celsius?

9/5C+32

What are intermolecular forces?

forces between molecules

what is the equation for pressure?

P=

F/A

-------------

P= pressure in (Pa)

F= force in newtons (N)

A= area in m²

Celsisu to faherint

(F-32) (5/9)

Equation to solve for the number of gas mols produced

n= (PV)/RT

Volume is read, R is known, T is given but P is (1atm-Ph2O)

what is the formula for root means square velocity (Urms)?

... M is molar mass

what value of R should you use?

8.314 J/molK

what is the formula for average speed/velocity

what is the equation for most probable speed?

peak of graph average

what is the equation for Joules (J)

What is Grahm's Law of Effusion equation?

faster / smaller molecules move through faster

Are intermolecular or intramolecular forces stronger?

intramolecular forces (ionic, covalant bonds) are stronger

What are some common intermolecular forces?

-Disperson forces/ London Disperson Forces,

-Dipole-dipole interactions,

-Hydrogen bonding

-Ion-dipole forces

What are Disperson/London dispersion forces?

-temporary attractions between an instantaneous dipole and an induced dipole

-transient event

What causes London dispersion forces?

-constant motion of electrons (partial positive and negative)

-induced dipole is caused by an electron being near it

-instantaneous dipole induces another

what molecules have london disperson forces?

every molecule

how do number of electrons and molecular weight impact london disperson forces?

-The more electrons, the stronger the dipole and is more likely to induce a dipole, stronger partial negatve

-The higher the molecular weight, the stronger

What is a dipole-dipole force?

-The attraction between the positive end of one polar molecule and the negative end of another

What is a dipole?

a molecule with a partial negative charge because of electronegativity differences

Dipole-dipole forces only work for what type of molecules?

Polar molecules

Is CH4 polar?

no, but it is neutral

What do polar molecules have?

permanent dipoles and are ASSYMETRIC

Are dipole-dipole interactions permanent?

yessss

How does electronegativity difference impact dipole-dipole interactions?

Increased difference means stronger force

What is hydrogen bonding?

hydrogen atom that is bonded to a highly electronegative atom (FON) is attracted to an unshared pair of electrons of an electronegative atom in a nearby molecule

-very strong force

what is required for hydrogen bonding?

F,O,N

what does hydrogen bonding cause?

-Weird properties of water like expanding when it freezes bc of the cystalline structure

-also why ice floats, low density

What are ion-dipole forces?

attractive forces between an ion and a polar molecule

-dissociation, ionic substance in polar substance

what is the strongest force?

ion-dipole

what occurs during ion-dipole forces?

the negative or postitve ion is strongly attracted to the pos or neg dipole

what is different about ion-dipole forces?

it is acutally positive or negative while otehr forces are partially, not fullly

what can intermoleular forces predict?

the state of matter

what do higher forces lead to?

higher melting and boiling points, makes it harder for phase changes because melting and boiling causes separation of molecules

-why water boils rlly high

What is viscosity? What are things with high viscosity called?

resistance to flow, viscous

The harder it is to flow...

the higher the viscocity

How does intermolecular forces affect viscocity? How does temperature affect viscocity?

-Higher interforces mean higher viscotity

-Higher the temp, the lower the viscocity

Is viscocity a coehsive or adhesive force?

Cohesive

What does cohesive forces mean?

Occurs between moleculars of the same thing

What does adhesive forces mean?

Occurs between two different things

What is surface tension? Is it an coehsive or adhesive force?

a measure of how hard it is to break the surface of a liquid

-why water puddles and beads up , hydrogen bonding

-cohesive

what molecules have high surface tension?

Hg and H2O

what is required to increase surface area of a liquid?

energy

What is capillary action? coehesive or adhesvie?

the attraction of the surface of a liquid to the surface of a solid,

tendency of polar substances to climb surfaces they are adjacent to

-adhesive force

What is a meniscus caused by?

capalliary action

Phase change: solid to liquid

melting

Phase change: liquid to solid

freezing

Phase change: liquid to gas

evaporation

Phase change: gas to liquid

condensation

Phase change: solid to gas

sublimation

Phase change: gas to solid

deposition

What is the heat/enthalpy of fusion ?

energy required to melt 1 mole of a substance

what is waters ΔHfus?

6.01 kJ/mol

what is heat/enthalpy of vaporization?

energy required to evaporate/boil 1 mole of a substance

what is waters ΔHvap?

40.7 kj/mol

what is heat/enthaply of sublimation?

energy required to sublimate 1 mole of a substance?

what is water ΔHsub?

46.7 kj/mol

heat of fusion + heat of vaporization =

heat of sublimation

here is a heating curve graph

the x axis can also be time

What do the flat parts mean?

phase change is happening

Why is the highest line/ vaporizing line so long?

It takes more energy to go from liquid to gas because it takes more energy to fully separate molecules

how to Hfus and Hvap relate to the chart?

they are the energy required to put in

What are the three heat equations?

q = mcΔT,

q=mΔHfus

q=mΔHvap

when do you use q = mcΔT

temperature changes

when do you use q=mΔHfus or q=mΔHvap?

Hfus, at the melting point and the other at the boiling point

What is the specific heat(C) of water as a liquid?

4.18 J/gk

What is the specific heat(C) of water as a solid?

2.09 J/gk

What is the specific heat(C) of water as a gas?

1.84 J/gk

What is specific heat?

amount of energy needed to raise 1 gram of a substance 1 degree Celsius

Phase diagram

a graph showing the conditions at which a substance exists as a solid, liquid, or vapor

What is the critical temperature?

The highest temperature at which a given substance can be a liquid

what is the critical pressure?

pressure at which the critical temperature substance is still a liquid

what is vapor pressure?

pressure exerted by a liquid when it reaches dynamic equllbrium

what is the supercritical fluid?

any substance at a temperature and pressure above its critical point, where distinct liquid and gas phases do not exist

What is the triple point?

the temperature and pressure at which all three phases of matter coexist in an equilibrium

how does temperature impact vapor pressure?

increase in temperature, increase in vapor pressure

what is boiling point?

when vapor pressure equals atmospheric pressure.. lower atm means lower bp... think mountains

how do IMF (intermolecular forces) impact vapor pressure?

the higher the IMF, the lower the VP

high VP means

volatile

Clausius-Clapeyron graph

an equation that displays the exponential relationship between vapor pressure and temperature

what is the slope equation?

slope= -ΔHvap/ R

What is the Clausius-Clapeyron equation?

ln[(P1/P2)]= (-ΔH/R)*[(1/T2) - (1/T1)]

R=

8.314 J/molK

the clausius-clapeyron equation has to be in what?

kelvin

ln sigfigs

ignore anything before the decimal

1 atm=

760 mmHg

760 torr

101.3 kPa

end of chapter 11

ok lets go again

What is the kinetic molecular theory?

based on the idea that particles of matter are always in motion

What are the ideal gas laws?

-Gas molecules are in constant, rapid, straight-line motion

-gas molecule collisions are elastic

-gas molecules have no volume

-gas molecules have no attraction for one another

what do elastic collisions mean?

the gas molecules bounce off each other with the same energy each time with no/negligible lost of energy

what parts of the ideal gas laws are somewhat true or false ?

-gasś do move in rapid straight line motions

-gas kind of have elastic collisions, some energy lost but small

-gas molecules do have some volume but very small amount

-no attraction for one another... just wrong

What are the 5 rules of the kinetic molecular theory?

1. Random motion

2. negliable molecular volume

3. negligible forces

4. constant average kinetic energy

-> some energy can be transferred during collisions but as long as temp is constant, average KE dont change

5. avg KE proportional to temperature

->at any given temp, the molecules of all gases have the same avg KE

what are some true facts about gases?

-no definate shape... takes shape of container

-no definate volume... equal to containers volume: means gas expands indefinitely until container reached

-gases are fluid (move around)

-low density

-form homogenous mixtures

-are compressible

-diffuse and effuse

-exert pressure

what does it mean to form homogenous mixtures?

evently distributed mixture

what are some unique things gases do that solids and liquids dont?

compressible and diffuse and effuse

What does diffusion mean?

movement of particals from high conentration to low concentration, rate gas fills the container

what does effusion mean?

rate at which gas molecules escape a small hole

What is pressure?what is it caused by?

Force per unit area. Caused by collisions

What is the formula for newtons?N=

(kg x m) / s²

s= seconds

What conditions cause more idealish gases?

High temp, low pressure

Standard pressure amounts

1 atm, 760 torr, 760 mm Hg, 101.3 kPa