CHEM 1008
saturated solution requirements
1. Solvent holds as much solute as is possible at that temperature. 2. Dissolved solute is in dynamic equilibrium with solid solute particles. 3. Rate of dissolution = Rate of crystallization 4. [solute] = solubility (s)
What is the molality of a solution produced by dissolving 14.40 g of LiCl (42.39 g/mol) in water to make 0.104 L of solution with a density of 1.102 g/mL?
3.39 m
A solution is prepared by dissolving 28.7 g of CaCl2 in 375 g of water. The density of the resulting solution is 1.05 g/mL. The concentration of CaCl2 is ________% by mass.
7.11 %
How many moles of solute are there in a 0.155 m glucose solution prepared with 50.0 kg of water?
7.75 mol
Ethanol (C2H5OH, MM = 46.00 g/mol) and methanol (CH3OH, MM = 32.00 g/mol) form an ideal solution when mixed. What is the vapor pressure of a solution prepared by mixing equal masses of ethanol and methanol? The vapor pressures of ethanol and methanol are 44.5 torr and 88.7 torr, respectively.
70.6 torr
example of gas in gas
air
solute
all other components (may be less than 1)
Automotive antifreeze consists of ethylene glycol (C2H6O2), a nonvolatile nonelectrolyte. Calculate the boiling point and freezing point of a 25.0 mass % solution of ethylene glycol in water.
bp=102.7 degrees C fp=-10.0 degrees C
solid in solid
bronze, pewter, 14K gold
When the barrier between the two liquids is removed, the randomness (entropy) of the molecules of both liquids ______. (increases or decreases)
increases
solvation
interaction between the solvent and solute
Quantitative expressions of concentration
require specific info regarding quantities like masses, moles, or liters of solute, solvent, or solution
2.A 30.0 g sample of potassium nitrate is dissolved in 100 g of water at 60 °C. The solution is cooled to 20.0 °C and a small amount of precipitate is observed. This solution is ________.
saturated
At constant T, if crystallization and dissolution are in equilibrium with undissolved solute, the solution is _____. (unsaturated, saturated, or supersaturated)
saturated
what are the three steps involving energy in the formation of a solution?
separation of solute molecules + separation of solvent molecules + formation of solute-solvent interactions -
if the solvent-solute interaction is greater or equal then _______.
solution forms
hypertonic
more concentrated solution; net solvent flow out
If you cannot reverse a change, the substance did not dissolve, it ______.
reacted
Nonvolatile solutes
reduce the ability of the surface solvent molecules to escape the liquid
finding m using M and d
(M x 1000)/ ((1000 x d)-(M x MM solute))
Indicate whether each of the following processes produces an increase or decrease in the entropy of the system:
(a) increase, (b) decrease, (c) decrease, (d) decrease
Predict the sign of ΔS, assuming each occurs at constant temperature:
(a) ΔS is positive (b) ΔS is negative (c) ΔS is negative (d) The sign of ΔS is impossible to predict but close to zero.
strong electrolytes
-100% ionized in water -i=total number of ions
Calculate the f.p. of an aqueous 30.0% ethylene glycol mixture. For water Kf = 1.86°C kg mol-1.
-12.8 deg C
Calculate the freezing point of a solution containing 0.600 kg of CHCl3 and 42.0 g of eucalyptol (C10H18O), a fragrant substance found in the leaves of eucalyptus trees. (See Table 13.3.)
-65.6 deg C
Colligative Properties (4)
-VP lowering (Raoult's Law) -BP elevation -FP depression -Osmotic Pressure (pi)
nonelectrolytes
-do not dissociate into ions at all -i=1
weak electrolytes
-partially ionized in water -1<i<total number of ions
what are the four most commonly used expressions for concentrations?
1. Mass % 2. Mole fraction (X) 3. Molarity 4. Molality
Indicate which aqueous solution has the slowest evaporation rate.
B
Maple syrup has a density of 1.325 g/mL, and 100.00 g of maple syrup contains 67 mg of calcium in the form of Ca2+ ions. What is the molarity (M) of calcium in maple syrup?
0.022 M
What is the osmotic pressure at 20 ºC of a 0.0020 M sucrose (C12H22O11) solution?
0.048 atm, or 37 torr
List the following aqueous solutions in order of their expected freezing point: 0.050 m CaCl2, 0.15 m NaCl, 0.10 m HCl, 0.050 m HC2H3O2, 0.10 m C12H22O11.
0.10 m HCl, 0.050 m CaCl2, 0.10 m C12H22O11, and 0.050 m HC2H3O2
Calculate the concentration of CO2 in a soft drink that is bottled with a partial pressure of CO2 of 4.0 atm over the liquid at 25 ℃. The Henry's law constant for CO2 in water at this temperature is 3.1 ^ 10-2 mol/L-atm.
0.12 M
The solubility of oxygen gas in water at 25 °C and 1.0 atm pressure of oxygen is 0.041 g/L The solubility of oxygen in water at 3.0 atm and 25 °C is __________ g/L.
0.12 g/L
The vapor pressure of benzene, C6H6, is 100.0 torr at 26.1 ºC. Assuming Raoult's law is obeyed, how many moles of a nonvolatile solute must be added to 100.0 mL of benzene to decrease its vapor pressure by 10.0% at 26.1 ºC? The density of benzene is 0.8765 g/cm3.
0.1248
Soft drinks "fizz" when opened. Calculate [CO2] when a drink is bottled (P = 4.5 atm), and after it's opened. For CO2 in water kH = 3.4 x 10-2 M/atm. The partial P of CO2 in the atmosphere = 3.1 x 10-4 atm.
0.15 M; 1.1 x 10-5 M
A solution contains 5.0 g of toluene (C7H8) and 225 g of benzene and has a density of 0.876 g/mL. Calculate the molarity of the solution.
0.21 M
A solution of SO2 in water contains 0.00023 g of SO2 per liter of solution. What is the concentration of SO2 in ppm?
0.23 ppm
The vapor pressure of pure water at 110 ºC is 1070 torr. A solution of ethylene glycol and water has a vapor pressure of 1.00 atm at 110 ºC. Assuming that Raoult's law is obeyed, what is the mole fraction of ethylene glycol in the solution?
0.290
How can solubility be expressed? (3)
1. Molarity (mol solute/L solution) 2. g solute/L solution 3. g solute/100 g H2O
The average osmotic pressure of blood is 7.7 atm at 25 ºC. What concentration of glucose (C6H12O6) will be isotonic with blood?
0.31 M (M=pi/RT) where R=0.0821
What is the molality of a solution made by dissolving 36.5 g of naphthalene (C10H8) in 425 g of toluene (C7H8)?
0.670 m
The concentration of lead nitrate in a 0.726 M solution is _______molal. The density of the solution is 1.202 g/mL.
0.755 molal
A solution is made by dissolving 4.35 g glucose (C6H12O6) in 25.0 mL of water at 25 ℃. Calculate the molality of glucose in the solution. (d of H2O = 1.00 g/mL)
0.964 m
ppm
1 mg solute/L of solution # of grams/10 ^6 g solution mg solute/kg solution
unsaturated solution requirements
1. Less than the maximum amount of solute for that temperature is dissolved in the solvent. 2. [solute] is less than the solubility (s)
equations for Molarity (2)
1. M=moles of solute/L of solution 2. M=mass of solute/ (MM solute x V solution in L)
supersaturated solution requirements
1. Solvent holds more solute than is normally possible at that temperature. 2. These solutions are unstable; crystallization can usually be stimulated by adding a "seed crystal" or scratching the side of the flask. 3. [solute] is more than the solubility (s)
True or False: 1.The b.p. of 0.001 M NaCl(aq) is the same as the b.p. of 0.001 M CsF(aq). 2.The f.p. of 0.100 m CaCl2(aq) is the same as the f.p. of 0.150 m KBr. 3.The b.p. of 0.100 m CaCl2(aq) is higher than the b.p. of 0.200 m KBr. 4.The v.p. of 0.100 m CaCl2(aq) is greater than that of 0.100 m LiF 5.The f.p. of 15% KCl(aq) is greater than that of 5% KCl(aq). 6.The f.p. of 5% NaBr(aq) is lower than that of pure water. 7.The rate of evaporation of 0.100 m CaCl2(aq) is the same as that of 0.100 m K2SO4. 8.The osmotic pressure (p) of pure water is 1.00 atm. 9.p of 0.10 M Al2(SO4)3 is higher than that of 0.10 M K3PO4
1. T 2. T 3. F 4. F 5. F 6. T 7. T 8. F 9. T
What two things does the ability of substances to form solutions depend on?
1. natural tendency toward mixing. 2. intermolecular forces (IMF).
•The tendency of a substance to dissolve in another substance depends on what? (4)
1. nature of solute 2. nature of solvent 3. T 4. P
On a clear day at sea level, with a temperature of 25 °C, the partial pressure of N2 in air is 0.78 atm and the concentration of nitrogen in water is 5.3 × 10-4 M. When the partial pressure of N2 is __________ atm, the concentration in water is 1.1 × 10-3 M.
1.6 atm
Summary of Colligative Properties
1.Vapor Pressure Lowering (a) P1 = X1 P°1 (b) Ptotal = X1 P°1 + X2 P°2 2.Boiling Point Elevation (a) DTb = Kb m I 3.Freezing Point Depression (a) DTf = Kf m I 4.Osmotic Pressure (p) (a) p = M R T i
1 ppm = ____ ppb
1000
a)Assuming complete dissociation of the solute, how many grams of KNO3 must be added to 275 mL of water to produce a solution that freezes at -14.5 ºC ? The freezing point for pure water is 0.0 ºC and kf for it is equal to 1.86 ºC/m. b)If the 3.90 m solution from Part A boils at 103.45 ºC, what is the actual value of the van't Hoff factor, i ? The boiling point of pure water is 100.00 ºC and Kb is equal to 0.512 ºC/m .
108 g 1.73
A solution is made by dissolving 13.5 g of glucose (C6H12O6) in 0.100 kg of water. What is the mass percentage of solute in this solution? (b) A 2.5-g sample of groundwater was found to contain 5.4 mg of Zn2+ What is the concentration of Zn2+ in parts per million (ppm)?
11.9 %; 2.2 ppm
Camphor (C10H16O) melts at 179.8 ºC, and it has a particularly large freezing-point-depression constant, Kf = 40.0 ºC/m. When 0.186 g of an organic substance of unknown molar mass is dissolved in 22.01 g of liquid camphor, the freezing point of the mixture is found to be 176.7 ºC. What is the molar mass of the solute?
110 g/mol
Which of the following solutes will produce the largest increase in boiling point upon addition to 1 kg of water: 1 mol of Co(NO3)2, 2 mol of KCl, 3 mol of ethylene glycol (C2H6O2)?
2 mol of KCl because it contains the highest concentration of particles, 2 m K+ and 2 m Cl-, giving 4 m in all
4.A solution is prepared by dissolving calcium chloride in water and diluting to 500.0 mL. If this solution contains 44 ppm chloride ions, the concentration of calcium ions is ________ ppm.
22 ppm
What is the vapor pressure at 25 °C of a 20% aqueous solution of a non-electrolyte with a molar mass of 121.3? The vapor pressure of water at 25 °C is 23.8 torr.
22.9 torr
Glycerin (C3H8O3) is a nonvolatile nonelectrolyte with a density of 1.26 g/mL at 25 ºC. Calculate the vapor pressure at 25 °C of a solution made by adding 50.0 mL of glycerin to 500.0 mL of water. The vapor pressure of pure water at 25 ºC is 23.8 torr (Appendix B).
23.2 torr
At 25 °C, the vapor pressure of pure water is 25.756 mm Hg. What is the vapor pressure of water in a 0.500 m solution of sodium chloride?
25.52
The solubility of Ar in water at 25 °C is 1.6 × 10-3 M when the pressure of the Ar above the solution is 1.0 atm. The solubility of Ar at a pressure of 2.5 atm is __________ M.
4.0 x 10 -3 M
A sample of 2.05 g of polystyrene of uniform polymer chain length was dissolved in enough toluene to form 0.100 L of solution. The osmotic pressure of this solution was found to be 1.21 kPa at 25 ºC. Calculate the molar mass of the polystyrene. (1 atm = 101.325 kPa)
4.20 x 10 ^4 g/mol
The solubility of nitrogen gas in water at 25 °C and a nitrogen pressure of 1.0 atm is 6.9 x 10-4 M. The solubility of nitrogen in water at a nitrogen pressure of 0.80 atm is __________ M.
5.5 x 10 -4 M
A solution is made by mixing 20.0 g of a nonvolatile compound with 125 mL of water at 25 °C has a vapor pressure of 22.67 torr. What is the molar mass of the compound?
57.8 g/mol
The osmotic pressure of an aqueous solution of a certain protein was measured in order to determine the protein's molar mass. The solution contained 3.50 mg of protein dissolved in sufficient water to form 5.00 mL of solution. The osmotic pressure of the solution at 25 ºC was found to be 1.54 torr. Calculate the molar mass of the protein.
8.45 x 10^3
A solution of an unknown nonvolatile nonelectrolyte was prepared by dissolving 0.250 g of the substance in 40.0 g of CCl4. The boiling point of the resultant solution was 0.357 ºC higher than that of the pure solvent. Calculate the molar mass of the solute.
88.0 g/mol
Calculate the concentration of CO2 in a soft drink after the bottle is opened and equilibrates at 25 ℃ under a CO2 partial pressure of 3.0 ´ 10-4 atm. The Henry's law constant for CO2 in water at this temperature is 3.1 ^ 10-2 mol/L-atm.
9.3 x 10-6 M
Commercial 30.0% hydrogen peroxide has density = 1.11 g/mL at 25 °C. What is its molarity?
9.79 M
All of the following are measures of solution concentration except: A) Moles (mol) B) molality (m) C) molarity (M) D) mole fraction (X) E) mass percentage (%)
A
Calculate the freezing point of a solution containing 5.0 grams of KCl and 550.0 g of water. The molal-freezing point depression constant for water is 0.86 °C/m.
A
Indicate which aqueous solution has the fastest evaporation rate.
A
Indicate which aqueous solution has the highest vapor pressure.
A
Which one of the following is most soluble in water? A) CH3OH B) CH3CH2CH2OH C) CH3CH2OH D) CH3CH2CH2CH2OH E) CH3CH2CH2CH2CH2OH
A
Which solution will have the lowest osmotic Pressure (p)? A.0.10 M sodium chloride B.0.10 M sodium phosphate C.0.10 M sodium sulfate D.0.10 M sodium carbonate E.0.10 M sodium sulfide
A
What is Vitamin A soluble in? Vitamin C?
A- nonpolar compounds like fats C- soluble in water
5.A 2.650×10−2 M solution of NaCl in water is at 20.0°C. The sample was created by dissolving a sample of NaCl in water and then bringing the volume up to 1.000 L. It was determined that the volume of water needed to do this was 999.3 mL . The density of water at 20.0°C is 0.9982 g/mL. A) Calculate the molality of the salt solution. 2.657×10−2 B) Calculate the mole fraction of salt in this solution. 4.782×10−4 C) Calculate the concentration of the salt solution in percent by mass. 0.1550 D) Calculate the concentration of the salt solution in parts per million. 1550 ppm
A. 2.657×10−2 B. 4.782×10−4 C. 0.1550 D. 1550 ppm
A 1.35 m aqueous solution of compound X had a boiling point of 100.702 °C. Which one of the following could be compound X? The boiling point elevation constant for water is 0.52 °C/m. A) Al2(SO4)3 (MM = 342.15 g/mol) B) C6H12O6 (MM = 180.156 g/mol) C) Na3PO4 (MM = 163.94 g/mol) D) KCl (MM = 74.55 g/mol) E) CaCl2 (MM = 110.98 g/mol)
B
Isopropyl alcohol has a boiling point of 82.3 °C. Solutions of isopropyl alcohol in water have normal boiling points less than 100 °C. Is this observation consistent with the following equation? Explain. a. No bp elevation only pertains to ionic solutes. b. No, bp elevation only pertains to nonvolatile solutes. c. Yes, bp depression occurs for all solutions. d. Yes, bp depression constant for isopropyl alcohol is large. e. No isopropyl alcohol can H Bond with water.
B
Which aqueous solution will have the lowest freezing point? (a) 0.050 m CaCl2, (b) 0.15 m NaCl, (c) 0.10 m HCl, (d) 0.050 m CH3COOH, (e) 0.20 m C12H22O11.
B
Mole fractions are typically used to calculate which properties for a solution containing nonvolatile solutes? (I)Freezing point depression (II)Osmotic pressure (III)Vapor pressure A)I only B)III only C)I and II only D)II and III only E)I, II, and III
B.
A solution contains 11% by mass of sodium chloride. This means that ________. A) there are 11 g of sodium chloride in in 1.0 mL of this solution B) 100 g of the solution contains 11 g of sodium chloride C) 100 mL of the solution contains 11 g of sodium chloride D) the density of the solution is 11 g/mL E) the molality of the solution is 11
C
A solution contains 15 ppm of benzene. The density of the solution is 1.00 g/mL. This means that ___________________________. A) there are 15 mg of benzene in 1.0 g of this solution B) 100 g of the solution contains 15 g of benzene C) 1.0 g of the solution contains 15 × 10-6 g of benzene D) 1.0 L of the solution contains 15 g of benzene E) the solution is 15% by mass of benzene
C
Rank the above solutions A, B, and C from the most endothermic to the most exothermic. A) A, B, C B) B, C, A C) C, B, A D) A, C, B E) C, A, B
C
Which is a colligative property? i.Osmotic pressure ii.Density iii.Freezing point iv.Vapor pressure v.Boiling point elevation A)(i) and (iii) B)(iii) and (iv) C)(i) and (v) D)(i), (iii), and (v) E)(i), (iii), (iv), and (v)
C
Which is true regarding the solvation of a solute in a solvent? A. Separation of solute molecules from one another is an endothermic process, and separation of solvent molecules from one another is an exothermic process. B. Separation of solute molecules from one another is an exothermic process, and separation of solvent molecules from one another is an endothermic process. C. Separation of solute molecules from one another, and separation of solvent molecules from one another, are both endothermic processes. D. Separation of solute molecules from one another, and separation of solvent molecules from one another, are both exothermic processes. E. Separation of solute molecules from one another, and separation of solvent molecules from one another, both result in a decrease in entropy.
C
Arrange the following substances in order of increasing solubility in water:
C5H12 < C5H11 Cl < C5H11 OH < C5H10(OH)2
BP elevation equation
Change Tb = Kb m i
Change of Tb
Change of Tb = bp in presence of solute - bp of pure solvent
How do you determine if H solution is positive or negative? What causes it to be positive or negative?
Consider the strengths of all solute solute, solvent solvent, and solute solvent interactions; IMF forces
A mysterious white powder could be powdered sugar (C12H22O11), cocaine (C17H21NO4), codeine (C18H21NO3), norfenefrine (C8H11NO2), or fructose (C6H12O6). When 80 mg of the powder is dissolved in 1.50 mL of ethanol (d = 0.789 g/cm3, normal freezing point -114.6 ºC, Kf = 1.99 ºC/m), the freezing point is lowered to -115.5 ºC. What is the identity of the white powder? (a)Powdered sugar (MM = 342.29648 g/mol) (b)Cocaine (MM = 303.353 g/mol) (c)Codeine (MM = 299.364 g/mol) (d)Norfenefrine (MM = 137.179 g/mol) (e)Fructose (MM = 180.156 g/mol)
D
Red-blood cells comprise an outer semi-permeable membrane, and are subject to osmosis. If local solute concentration outside the cells is higher than that inside: A) no net solvent migration will occur B) solvent will migrate from inside the cell to the outside but not from outside in C) solvent will migrate faster into the cell than out of it causing the cell to burst D) solvent will migrate faster out of the cell than into it causing the cell to crumple
D
The most likely van't Hoff factor (i.e., experimental value) for an 0.01 m CaI2 solution is ________. A) 1.00 B) 3.00 C) 1.27 D) 2.69 E) 3.29
D
When argon is placed in a container of neon, the argon spontaneously disperses throughout the neon because ________. A) of the large attractive forces between argon and neon atoms B) of hydrogen bonding C) a decrease in energy occurs when the two mix D) the dispersion of argon atoms produces an increase in disorder E) of solvent-solute interactions
D
Which of the following actions will raise the osmotic pressure of a solution? (a)Decreasing the solute concentration (b)Decreasing the temperature (c)Adding more solvent (d)Increasing the temperature (e)None of the above
D
You double the partial pressure of a gas over a liquid at constant temperature. Which of these statements is then true? (a) The Henry's law constant is doubled. (b) The Henry's law constant is decreased by half. (c) There are half as many gas molecules in the liquid. (d) There are twice as many gas molecules in the liquid. (e) There is no change in the number of gas molecules in the liquid
D
enthalpy change in the solution process formula
DHsoln = DH1 + DH2 + DH3 where D is delta
FP depression equation
DTf = Kf.m.i
A solution is prepared by dissolving 7.00 g of glycerin in 201 g of ethanol. The freezing point of the solution is __________ °C. The freezing point of pure ethanol is -114.6 °C at 1 atm. The molal-freezing-point-depression constant for ethanol is 1.99 °C/m. The molar masses of glycerin and of ethanol are 92.1 g/mol and 46.1 g/mol, respectively. A) -121.3 B) 0.752 C) -107.9 D) -113.8 E) -115.4
E
Considering that ideal behavior is not always found in nature, which of the following aqueous solutions would you expect to have the largest experimental van 't Hoff factor? A)0.100 m C12H22O11 (sucrose) B)0.100 m NH4Cl C)0.100 m (NH4)2SO4 D)0.001 m NH4Cl E)0.001 m (NH4)2SO4
E
Of the following, a 0.100 m aqueous solution of ________ will have the highest freezing point. A) NaCl B) Al(NO3)3 C) K2CrO4 D) Na2SO4 E) C12H22O11
E
Proteins frequently form complexes in which 2, 3, 4, or even more individual proteins ("monomers") interact specifically with each other via hydrogen bonds or electrostatic interactions. The entire assembly of proteins can act as one unit in solution, and this assembly is called the "quaternary structure" of the protein. Suppose you discover a new protein whose monomer molar mass is 25,000 g/mol. You measure an osmotic pressure of 0.0916 atm at 37 ºC for 7.20 g of the protein in 10.00 mL of an aqueous solution. How many protein monomers form the quaternary protein structure in solution? Treat the protein as a nonelectrolyte. (a) 1, (b) 2, (c) 3, (d) 4 , (e) 8.
E
What is the freezing point of a solution prepared from 50.0 g ethylene glycol (C2H6O2) and 85.0 g H2O? [For water, Kf = 1.86 °C/m]
E
Which one of the following is most soluble in hexane (C6H14)? A) CH3OH B) CH3CH2CH2OH C) CH3CH2OH D) CH3CH2CH2CH2OH E) CH3CH2CH2CH2CH2OH
E
Which statement below regarding vapor pressure is not correct?
E
reverse osmosis
Flow is reversed if P > pi is applied.
Which liquid is more viscous: 1-propanol or glycerol?
Glycerol because stronger IMF
gas in solid
H in Pd metal
Molarity equation relating to ppm
M=#ppm x 10-3 / MM M=ppb x 10-6 /MM
mass using M
Mass (g)= M x MM x V in L
In general, solutions form if the DHsoln is _____.
Negative
Does solubility of liquids and solids change appreciably with P?
No
Is molality dependent on T? Why or why not?
No because moles and mass dont change w T.
Does NaCl dissolve in gasoline? Why or why not?
No because only weak interactions between NaCl and gas are possible because polar and nonpolar.
Osmotic pressure (pi)
P that must be applied to stop osmosis; increases as M x i increases
Raoult's Law equation
Pa = XaP°a where Pa=P of A in presence of solute, Xa is mole fraction of solvent A, and P°a is VP of solvent A
Raoult's Law for an Ideal Solution
Ptotal = (XA.P°A) + [(1-XA).P°B]
Henry's Law
Sg= kPg where Sg is Solubility, k is Constant, and Pg is partial pressure in atm S1/S2=P1/P2 k=M/atm where k is solubility and P=1 atm
Does the entropy of the system increase or decrease when the stopcock is opened to allow mixing of the two gases in this apparatus? Why or why not?
The entropy increases because each gas eventually becomes dispersed in twice the volume it originally occupied.
The vapor P of an aqueous solution of urea is 291.2 mmHg. The vapor P of pure water is 355.1 mmHg. Calculate the mole fraction of each component.
Xwater = 0.820 Xurea = 0.180
Is glucose soluble in water? Why or why not?
Yes because they both have H bonds and are polar
Does Molarity vary with T? Is density of the solution needed to calculate M?
Yes; yes
An aqueous solution of hydrochloric acid contains 36% HCl by mass. (a) Calculate the mole fraction of HCl in the solution. (b) Calculate the molality of HCl in the solution.
a. 0.22 b. 15 m
A commercial bleach solution contains 3.62 mass % NaOCl in water. Calculate (a) the molality and (b) the mole fraction of NaOCl in the solution.
a. 0.505m b. 9.00 x 10 ^-3
Sea water is 10,600 ppm Na+. Calculate (a) the mass percent and (b) molarity of sodium ions in sea water. The density of sea water is 1.03 g/mL
a. 1.06 % b. 0.475 M
A solution containing equal masses of glycerol (C3H8O3) and water has a density of 1.10 g/mL. Calculate (a) the molality of glycerol, (b) the mole fraction of glycerol, (c) the molarity of glycerol in the solution.
a. 10.9 m b. 0.163 c. 5.97 M
(a) Calculate the mass percentage of NaCl in a solution containing 1.50 g of NaCl in 50.0 g of water. (b) A commercial bleaching solution contains 3.62 mass % sodium hypochlorite, NaOCl. What is the mass of NaOCl in a bottle containing 2500 g of bleaching solution?
a. 2.91% b. 90.5 g of NaOCl
Consider a solution that contains 14.6 g of CH3OH (MM = 32.04 g/mol) in 184 g of H2O (MM = 18.02 g/mol). Calculate (a)mass % of CH3OH (b)mole faction of CH3OH (c)molality of CH3OH
a. 7.35 % b. 0.0427 c. 2.48 m
As temperature increases, solubility of solids generally _____.
increases
What does Raoult's Law predict?
as X solute increases, Pa gets lower
In general, the solubility of gases in water _____with increasing molar mass (MM).
increases
Suppose you take a solution and add more solvent, so that the original mass of solvent is doubled. You take this new solution and add more solute, so that the original mass of the solute is doubled. What happens to the molality of the final solution, compared to the original molality? (a) It is doubled. (b) It is decreased by half. (c) It is unchanged. (d) It will increase or decrease depending on the molar mass of the solute. (e) There is no way to tell without knowing the molar mass of the solute.
c
Increasing the number of -OH groups within a molecule _____ its solubility in water. (decreases or increases)
increases
ex of gas in liquid
carbonated drinks
Change of Tf
change of Tf= fp of pure solvent - fp in presence of solute
The more dilute the solution, the _____ the value of iexp to ilim
closer
solvent
component in the greatest amount
When a solution freezes, what happens first?
crystals of pure solvent are formed
Even though enthalpy may increase, the overall energy of the system can still _______ if the system becomes more disordered.
decrease
Solubility in water ______ as alcohols grow larger.
decreases because solute solute attraction grows and solute solvent stays constant.
The decrease in freezing point (DTf) is _____ proportional to molality.
directly
The increase in boiling point (DTb) is ______ proportional to molality. (directly or indirectly)
directly
The solubility of a gas in a liquid is ______ proportional to its pressure. (directly, indirectly)
directly
miscible liquids
dissolve in all proportions
Breaking is always _____; Forming is always _____.
endothermic, exothermic
An endothermic process will take place if it leads to an increase in _____.
entropy
immiscible liquids
form distinct separate phases
Because of solute-solvent intermolecular attraction, higher concentrations of nonvolatile solutes make it _____ for solvent to escape to the vapor phase. (easier or harder)
harder
MgSO4 is used in _____ and NH4NO3 is used in _____.
heat packs, cold packs
Which of the following solvents will best dissolve wax, which is a complex mixture of compounds that mostly are CH3-CH2-CH2-CH2-CH2—? a) hexane b) benzene c) acetone d) carbon tetra chloride e) water
hexane because it is most similar to structure of wax
Nonvolatile solute-solvent interactions also cause solutions to have _____ boiling points than the pure solvent.
higher
Solution
homogeneous mixture of solute and solvent
Change of T does not depend on what the solute is, but only on what?
how many particles are dissolved
How can the solubility of any gas in a liquid always be increased?
increase the P
Gases are ______ soluble at higher temperatures. (more or less)
less
Nonvolatile solute-solvent interactions also cause solutions to have____ freezing points than the pure solvent. (higher or lower)
lower
The solution freezes at a _____ temperature than the pure solvent.
lower
The vapor pressure of a solution is _____ than that of the pure solvent. (higher or lower)
lower
hypotonic
lower osmotic pressure; net solvent flow in
The reason at heat is absorbed, not released is because increasing the disorder or randomness (known as entropy, S) of a system tends to ________________.
lower the energy of the system
Things do not tend to occur spontaneously unless the energy of the system is _____.
lowered
Commercial concentrated aqueous ammonia is 28% NH3 by mass and has a density of 0.90 g/mL. What is the molality (m), mole faction (X), and molarity (M) of this solution?
m = 22.875 X = 0.2917; 0.7083 M= 14.8
finding m using M
m= (M x 1000)/mass of solvent (g)
mass percent of A (%)
mass of A in solution/total mass of solution x 100
parts by mass
mass solute/mass solution x mult factor
ppb
micrograms solute/kg solution grams of A/10^9 g solution 1 mg solute/L solution
Molarity
mol solute/L solution
Molality
mol solute/kg solvent
mole percent
mol solute/total mol solution x 100
mole fraction
mol solute/total moles solution
liquid in liquid
motor oil, vinegar
osmosis
movement of solvent through a semipermeable membrane from dilute to more concentrated solution
percent by mass
multiplication factor -100
ppm by mass
multiplication factor =10^6
ppb by mass
multiplication factor=10^9
triple point
occurs at lower temp because of lower VP for solution
solid in liquid
ocean water, sugar water
crystallization
opposite of a solution Solution-->solute + solvent
isotonic
osmotic pressure is same on both sides of a membrane; no osmosis will occur
dissolution
physical change you can reverse
equation for osmotic pressure
pi = MRTI
colligative properties
properties of the solvent that change when a nonvolatile solute is added to a solvent
Raoult's Law
quantifies the extent to which a nonvolatile solute lowers the VP of the solvent
What do changes in colligative properties depend on?
quantity/number of solute particles present (not identity of solute particles)
entropy (S)
randomness/disorder
Processes occurring at a constant temp in which the entropy of the system increases tend to occur _______.
spontaneously
A sample of potassium nitrate (49.0 g) is dissolved in 101 g of water at 100 °C, with precautions taken to avoid evaporation of any water. The solution is cooled to 30.0 °C and no precipitate is observed. This solution is ________.
supersaturated
solubility
the maximum amount of solute required to form a saturated solution at certain temp for a given quantity of the solvent.
environmental application example of gasses being less soluble at high temps
thermal pollution (causes fish to suffocate)
What happens to Pressure and Solubility when a carbonated beverage is opened?
they both decrease
semipermeable membrane
thin material that allows passage of small particles
How is the solute dispersed in the solvent of a solution?
uniformly
1.The solubility of MnSO4 monohydrate in water at 20 °C is 70.0 g per 100.0 mL of water. A solution at 20 °C that is 0.401 M in MnSO4 monohydrate is best described as a(n) ________ solution. The formula weight of MnSO4 monohydrate is 168.97 g/mol.
unsaturated
Why can molarity change with Temp?
volume is T dependent
Parts by volume (%, ppm, ppb)
volume solute/volume solution x multiplication factor
hydration
water is the solvent
BP elevation
•A nonvolatile solute lowers the vapor pressure of a solution. •At the normal boiling point of the pure liquid, the solution has a vapor pressure less than 1 atm. •Therefore, a higher temperature is required to reach a vapor pressure of 1 atm for the solution
Predict whether each of the following substances is more likely to dissolve in carbon tetrachloride (CCl4) or in water: C7H16, Na2SO4, HCl, and I2.
•C7H16 and I2 are soluble in CCl4 • Na2SO4 and HCl are soluble in water
