Is it Miscible or Immiscible?
When a saline solution is formed between Table Salt (NaCl) and Water (H2O). What are the predominant IMF of H2O & NaCl, and what IMF is predominant between H2O and NaCl?
H2O -> Hydrogen Bonding
NaCl -> Ionic Bonding
H2O + NaCl -> Ion Dipole Forces
If you heat a solvent such as water to high temperatures, and then add a solute such as Potassium Chloride, then cool the solution down, and then you observe a precipitate, what can you infer regarding the saturation of the Potassium Chloride solution?
it is saturated
Say you find a sample of 13.0 mL of crude oil in an area that contains 50.0 mg of Octane. What is the concentration of Octane in this sample in g/100 mL?
(0.050 g)/(13.0 mL) = (x g)/(100 mL)
conc. = 0.385/100 g/mL
In the winters of many colder places such as the Midwest, roads are salted in the winter to avoid large accumulation of snow and ice on the roads by allowing for the snow and ice to readily melt. Referring to material we have learned about in Chapter 13 & Chapter 11, why does road salting cause the snow to melt?
Because of the IDF forces that arise between the snow particles and the salt particles cause disruptions in the crystal lattice of the snow, allowing for it to readily melt.
The Henry's law constant for CO2 is 3.4*10-2 M/atm at 25oC. Under a constant pressure of 2.7 atmospheres, what will its solubility be in solution under these conditions?
S = (3.4*10-2 M/atm)*(2.7 atm)
= 0.0918 M
For a mixture between Water and Vitamin K, Can the IMF between them allow for a solution between these two compounds to spontaneously form? Why or Why not.
It cannot, because even though Vitamin D has some polar groups, it is still dominated by LDF, and therefore will not spontaneously form a solution with Water, which is predominated by Hydrogen bonding.
Suppose you dissolve 167.4 g of KNO3 in 270 mL of water at 50oC. When you cool the solution down to 20oC, no precipitate is observed. Knowing that water has a density of 1 g/mL, is the solution unsaturated, saturated, or super saturated?
Solution cannot be saturated, no ppt observed
(167.4 g)/(270 g) = x/(100 g)
x = 62 g
62 g/100 g H2O is super saturated at room temperature for KNO3
Consider the following reaction:
Hg(CNO)2(aq) -> Hg2+(aq) + 2CNO-(aq)
If we start with 17 ppm of the Hg(CNO)2, what is the concentration of the Hg2+ and CNO- in the solution?
Ratio = 1:1:2
Hg2+ = 17 ppm
CNO- = 34 ppm
Which Ionic compound has a larger Vant Hoff factor, Calcium Benzoate (Ca(C7H5O2)2), or Potassium Permanganate (KMnO4)?
Calcium Benzoate (produces 3 particles instead of the 2 particles of Potassium Permanganate)
Suppose you have 118 grams of Tert-Butanol (MM = 74.12 g/mol) dissolved in 485 mL of Ethyl Acetate (d = 0.902 g/mL, MM = 88.11g/mol). If pure Ethyl Acetate has a Vapor Pressure at 25oC of 96 torr, what is the vapor pressure of this solution?
(118/74.12) mol Tert-Butanol
((485*0.902)/88.11) = mol Ethyl Acetate
X = (437.47/88.11)/((437.47/88.11)+(118/74.12))
=~ 0.757
P = 0.757*96 torr
= 72.7 torr
When determining if a solution forms, ΔH is the primary indicator for bond strength both Intramolecular bonds like we learned about in Gen Chem 1 & Intermolecular Bonds (IMF). For the overall ΔH for the dissolution, what value must it have for a solution to spontaneously form? (Hint: -ΔH is exothermic, +ΔH is endothermic)
The overall ΔH must be negative for a soltion to form spontaneously
Consider a 0.241 M solution of K2Cr2O7 at room temperature (20oC). Is this solution unsaturated, saturated, or super saturated?
unsaturated
294.18 g/mol K2Cr2O7
7.1 g/100 g H2O
d = 1.0 g/mL
(7.1/100)*2.5 = 17.75/250
17.75/294.18 = (6.034*10-2 mol)/ 0.250 L = 0.241 M
Say you have a jug of glacial acetic acid (CH3COOH(aq)), which is at a concentration of 17 M. If you wish to use 123 mL of your glacial acetic acid, how many grams of Acetic acid are in the solution?
MM Acetic Acid = 60.06 g/mol
(12.01(2) + 16.00(2) + 1.01(4)) g/mol = 60.06 g/mol
(17 mol/L)*(0.123 L) = (2.091 mol)*(60.06 g/mol) = 126 g
Consider you are working with a solution of 2M NaOH at 27oC. What will this solution's osmotic pressure be? (R = 0.08206 L*atm/(mol*K)
π = MRTi
i = 2
T = 27 + 273 = 300 K
π = (2 mol/L)*(0.08206 L*atm/(mol*K))*(300 K)*(2)
= 99 atm
Soap is a common detergent used for its unique ability to dissolve a broad range of debris when used for cleaning. It has this property because it is amphipathic, or in other words, it has a strongly polar head and a non polar hydrocarbon tail. If the Soap happens to have an ionic polar head, what IMF is the head dominated by? What IMF is the tail dominated by?
Head -> Ionic Bonding or IDF in solution
Tail -> LDF
(x g)/327 g = 25 g/ 100 g
x = 81.75 g
Consider we create a 0.9% saline solution with Sodium Chloride & Water. What will the freezing point depression for this solution be? (Water's freezing point depression constant is 1.86 oC*kg/mol)
NaCl i = 2
0.9% by mass means 9.0 g NaCl in 1000-9 = 991 g H2O
MM NaCl 55.44 g/mol, ((9 g)/ (55.44 g/mol)) = 0.162337662 mol
(0.162337662 mol)/(0.991 kg) = (x mol)/(1 kg)
x = 0.164 m
ΔT = (2)*(1.86 oC*kg/mol)*(0.164 mol/kg) = 0.610 oC
Or in other words, Water's freezing point will fall by 0.610 oC
Consider we want to make a solution of Dichloromethane with Pyridine. You wish to use 273 mL of Dichloromethane and 57.0 g of Pyridine. What will the molality of this solution be when it is mixed together? The molar mass of Pyridine is 79.10 g/mol, and the density of Dichloromethane is 1.33 g/mL at room temperature, which is the ambient temperature.
(273 mL)*(1.33 g/mL) = 363.09 g
(57.0 g)/(79.10 g/mol) = 0.7206 mol
m = (0.7206 mol)/(0.36309 kg) = 1.98 m