chem112 exam
how much energy is absorbed when 355 g of acetone is vaporized at 56.1 C? (acetone boiling point is 56.1)
(355g)(1mol acetone/58.0791g acetone)(29.1 kJ/1mol aceteone)= 178 kJ
c to f
(C x 1.8) + 32
c-f
(C x 1.8) + 32
f-k
(F - 32) * 5/9 + 273.15
f to c
(F-32)/1.8
f-c
(F-32)/1.8
K-f
(K-273.15)*9/5+32
specific heat capacity
(c)energy required to raise the temperature of a specific amount of substance by one degree water per gram 2.087 j /g C (s), 4.184 j/g C (l) , 2.042 j/gC (g) per mole 47.6 j/m C (s), 75.37 J/mol C(l), 36.03 J/mol C (g)
R=
0.08206 L atm/mol K
log(2.2)=
0.34 10^.34=2.2 calculator 10^x (.34)=2.2
ln(2.2)=
0.79 ln=loge log (2.71)^2.2 e^(.79)=2.2 log(2.2)/log(2.71)= 0.79
torr to mmHg
1 torr = 1 mmHg
solve for x 81=13^x
1.71 log13 81 means what power do I need to take 13 to to get 81 13^1.71=81 in calculator log(81)/log(13)
liquid water enthalpy of vaporization
100 C 40.7 kj/mol 25 C 44.0 kj/mol
1atm= kpa?
101.3kpa = atm?
1 atm = mbarr?
1013.25 mbar = atm?
na2so4 how dissociate into how many ions?
3 ions 2 na, 1 so4
1 atm
760 mmHg
torr-atm
760torr=1atm
lnp2/lnp1 =
= lnp2 - lnp1
propanol has a normal boiling point of 97.00 C and a heat of vaporization of 41.2 kj/mol. What is the vapor pressure of propanol at 61.00 C, in mmHg?
=180mmHg T2=97.00 C --> 370.15K P2= 760 mmHg T1= 61.00 C --> 334.15 K ln p2/p1= ΔH vap/R (1/t1 - 1/t2) ---> lnP2-lnP1 ΔH vap in j/mol instead of kj/mol to consistent with R 41.2kj/mol --> 41200j/mol R=8.3145 J/k mol ln(760mmHg)-lnP1= (41,200 j/mol)/(8.3145 J/K mol) ((1/334.15K)-(1/370.15K)) ln(760mmHg)=6.633 6.633-lnP1=1.422 lnP1=6.633-1.442=5.191 P2=e^5.191=180mmHg
e
=2.71
Solvent
A liquid substance capable of dissolving other substances water (solvent) salt (solute)
polar molecule
A molecule that has electrically charged areas.
solute
A substance that is dissolved in a solution.
solute
A substance that is dissolved in a solution. salt (solute) and water (solvent)
Ion
An atom or group of atoms that has a positive or negative charge. unequal amount of protons and electrons
Adhesion
An attraction between molecules of different substances concave meniscus in container if more attracted to container
electrolytes
Aqueous ionic compuounds, and strong acids acids (metal or ammonium ions) (nh4+) 100% ionization al2(so4)3 = 5 ions (2 al3+, and 3 (so4)2-) more particles = higher boiling point
Cohesion
Attraction between molecules of the same substance convex meniscus in container if more attracted to itself
c-k
C + 273.15
henrys law
C=kP
Allotropes
Different forms of the same element
exceptions to the octet rule
Hydrogen (2), Boron (3-6), Aluminum(sometimes 6, but 3), Phosphorus(10), Sulfur(up to 12).
k-c
K-273.15
Buckyball
Molecule composed of 60 carbon atoms arranged in a sphere. c60
ln P2/P1= ΔH vap/R (1/t1 - 1/t2)
Pvap(torr) 450 720 T(K) 270 370 lnPvap 6.11 6.58 1/T (K^-1) 0.0037 0.0027 ln P2/P1= ΔH vap/R (1/t1 - 1/t2) ln 720torr/450torr=ΔH vap/ 8.3145 J/k mol (1/270 - 1/370) 0.470=ΔH vap/8.3145 j/K mol (0.0010 K^-1) ΔH vap=8.3145 J/K mol (0.470) / 0.0010 K =3907.815 j/mol ==3.9k kj/mol
lnPvap=-ΔH vap/R (1/T) +lnB
Pvap(torr) 450 720 T(K) 270 370 lnPvap 6.11 6.58 1/T (K^-1) 0.0037 0.0027 lnPvap=-ΔH vap/R (1/T) +lnB y=mx+b m=-ΔH vap/R m(slope)= is y2-y1/x2-x1 (6.58-6.11)/(0.0027-0.0037)=-470 K slope=-ΔH vap/R ---> ΔH vap=-slopexR -(-470K) R --> - (-470K) (8.3145 J/k mol) 3907.815 j/mol -- 3.9 kj/mol
Dipole attractions
The attraction of the δ- end of one polar molecule to the δ + end of another polar molecule. medium intermolecular force CO - CO aka polar interactions
van der Waals forces
a slight attraction that develops between the oppositely charged regions of nearby molecules aka london dispersion forces weakest intermolecular force only intermolecular force that exists between nonpolar molecules or atoms
molecular solid
a solid that consists of atoms or molecules held together by intermolecular forces
capillary action
adhesion + cohesion of liquid
bond polarity
arrow is pointing toward more electronegative atom 2.5 C <----+ H 2.1 (np)
hydrogen bonds
attractive forces in which a hydrogen covalently bonded to a very electronegative atom is also weakly bonded to an unshared electron pair of another electronegative atom H-- N, O, F strongest intermolecular force a type of dipole attraction h cov bond to n,o,f --- n,o,f lone pair hf hbond is stronger than h2o hbond
cis/trans isomer
cis has 2 groups on same side trans has 2 groups on different side c2h2cl2
coal, diamond, pencils
coal (amorphous carbon) diamond (crystalline form carbon) pencils (graphite, type of carbon) allotropes of carbon
lattice energy
decreases as size of ion increases
Electronegativity
desire to gain an electron nonmetals have high electronegativity (F-) metals have low (Na+) increases toward fluorine
electrolytes
dissociate into ions salts, strong acids
non electrolyte
do not dissociate into ions
Covalent Bond
electrons are shared H2O polar and non polar polar covalent bonds, electrons shared unevenly electronegativity difference less than .5 is considered nonpolar greater polar (there is no true agreement) greater than 1.8 is ionic rather than covalent
ionic bond
electrons are transferred metal and non metal NaCl
Enthalpy (ΔH)
energy it takes to phase change ΔHfus=334 j/g ΔHvap= 2260 j/g
ΔHsub
energy required for sublimation of 1 mol of a solid ΔHsub= ΔHfus+ΔHvap ΔHsub= 6.01 kj/mol + 40.7kj/mol = 46.7 kj/mol
surface tension
energy required to increase the surface area of a liquid/force required to increase the length of a liquid surface by a given amount caused by unbalanced net inward attraction of the molecules along the surface of a liquid mercury has a very high surface tension tendecy of a liquid to reduce its surface area
ΔHfus
energy required to melt 1 mol of a solid ΔHfus of water is 6.01 kj/mol
ΔHvap
energy required to vaporize 1 mol of liquid ΔHvap of water is 40.7kJ/mol in kj/mol or j/mol
i-factor
equal to number of particles in solution when 1 mole of substance dissolves in water NaCl= Na+, Cl- = i=2 HNO3 = H+, NO3- = i =2
intermolecular forces
forces of attraction between molecules liquid and solid state weak and temporary melting and boiling point increase as intermolecular forces increase ion-dipole>hydrogen bonding>dipole-dipole>dispersion
R
gas law constant 8.3145 J/mol K
deposition
gas---->solid
enthalpy of vaporization
j/mol energy required for the vaporization of 1 mol of a liquid
methanol has a normal boiling point of 64.60 c and a heat of vaporization of 32.5 kj/mol. What is the vp of methanol at 25.00C in mmHg
ln p2 - ln p1= Hvap/R (1/T1 - 1/T2) ln(760 mmHg) - ln p1= 35200 J/mol / 8.3145 j/k mol (1/298.15k - 1/337.75k) reciprocals before subtracting 6.633 -lnp1= 1.66 lnp1= 6.633- 1.66 = 4.97 P2=e^4.97=144mmHg
ln(x/y)=
lnx-lny=
ln x
log e x
electron pair repulsion
lone pair- lone pair >lone pair - bonding pair> bonding pair-bonding pair lone pair> triple bond > double bond> single bond
vapor pressure, hvap
low vp, high hvap hvap is energy required to vaporize 1mol of substance
molar mass
molar mass =g/mole moles=g/molar mass g=molar mass x moles
molality
moles of solute/kg of solvent 0.05 mole NaCl/1kg H2O
molarity
moles of solute/liters of solution
surface area effects
more contanct between molecules=stronger dispersion forces (isomers)
crystalline solids
nacl crystal lattice (repeating pattern)-unit cell defined by position of atoms in unit cell simple, body centered, face centered uniform = one specific melting point
amorphous solids
no orderly internal structure no specific melting point (gradually soften) (butter), rubber, glass imfs not evenly distributed
nonvolatile
not easily vaporized
bond type electronegativity
pure covalent <0.4 polar covalent 04.-1.8 ionic >1.8
ΔH fus, vap, sub in j/g
q=m(ΔH) m=mass q=j
ΔH fus, vap, sub in kj/mol
q=n(ΔH) q=kj n=moles
Clausius-Clapeyron equation
relationship between vapor pressure, temperature, and enthalpy of vaporization lnPvap= -ΔHvap/R (1/T) +ln b pvap= vapor prsssure in atmospheres R= 8.3145 J/mol K T temperature in kelvins b is a constant specific for each liquid ln p2/p1= ΔH vap/R (1/t1 - 1/t2) in order for hvap to be positive in this equation 2 has to be divided by 1 in p and minus 1 in t, if they are both first hvap is negative in this equation lnp2/p1=-hvap/r(1/t2-1/t1)
Viscosity
resistance of a liquid to flow depends on intermolecular forces, size of molecules, and temperature of the liquid intermolecular forces up viscocity up size/surface area up viscocity up temperature up viscosicty down
crystalline solid
solid made of repeating pattern
phase changes
solid to liquid = melting liquid to gas = vaporization gas to liquid= condensation liquid to solid = freezing solid to gas= sublimation gas to solid= deposition
amorphous solid
solid with random arranged does not have definite melting point
Sublimation
solid--->gas
covalent network solids
solids in which the units that make up the three-dimensional network are joined by covalent bonds
metallic solids
solids that are composed of metal atoms
ionic solids
solids whose composite units are ions; they generally have high melting points
capilary action
tendency of water to rise in a thin tube
ion-dipole
the charge of an ion is attracted to the partial charge on a polar molecule Na+ and H2O
solvent
the substance in which the solute dissolves
volatile
vaporize easily
formal charge
ve-(b+d)
boiling point
vp=1atm