Phase Changes
What is it called when a liquid is converted to a solid?
Freezing or crystallization
Will CH3OH or CCl4 dissolve better in water?
CH3OH
Is the viscosity high or low when IMFs are weak?
Viscosity is low
List the IMFs from weakest to greatest.
Dispersion<D-D<H-Bonding<I-D
What is the Clausius-Clapeyron equation?
ln P2/P1= -ΔHvap/ R (1/t2-1/t1)
What happens to the entropy as a liquid evaporates into a gas? (Is entropy positive or negative?)
S= +
What is the formula for Molarity? Molality?
M= mol/L solution
m= mol/ kg solvent
Calculate the mass percent of chlorine in CuCl.
35.8%
What is the IMF for H2S?
D-D
Will CH3CH2CH2CH2Br or CH3Br have a higher Boiling point?
CH3CH2CH2CH2Br
What is it called when a gas turns into a solid?
Deposition
Calculate the molality of 25.0 grams of KBr dissolved in 750.0 mL of pure water.
25.0 g/119.0 g/mol = 0.210 mol
0.210 mol/0.750 kg = 0.280 m
What time is your exam?
6:00pm
Which elements can form a H-bond?
H-N,O,F
Will straight chained or branched molecules have a higher boiling point?
Is delta H positive or negative during sublimation?
Negative
What is meant by “like dissolves like?”
Polar dissolves in polar
nonpolar dissolves in nonpolar
The edge length of the unit cell of Ta, is 330.6 pm; the unit cell is body-centered cubic. Tantalum has a density of 16.69 g/cm3. calculate the mass of a tantalum atom.
3.015 x 10¯22 g
IMF _____ as vapor pressure ______.
Increases, decreases
vice versa
how Do you solve for x in ln(103/x)=5
e^ln(103/x)=e^5
103/x=#
103=x#
x=103/#
Is condensation endothermic or exothermic?
Exothermic
0.100 mole of NaCl is dissolved into 100.0 grams of pure H2O. What is the mole fraction of NaCl?
100.0 g / 18.0 g mol¯1 = 5.56 mol of H2O
Add that to the 0.100 mol of NaCl = 5.56 + 0.100 = 5.66 mol total
Mole fraction of NaCl = 0.100 mol / 5.66 mol = 0.018
How much energy in joules will it take to melt 348g of ice? Hfus=6.01 kJ/mol
116,193
with sig figs 1.16x10 5
What is the IMF for I2?
Dispersion
Carbon tetrachloride has a vapor pressure of 213 torr at 40.0 °C and 836 torr at 80.0 °C. What s the enthalpy of vaporization in kJ/mol?
ΔHvap = [(-8.314 J/mole K) x ln (213 torr / 836 torr)] / (1/313.15 K - 1/353.15 K)
ΔHvap = 31.4 kJ/mole