Chapter 11 Solutions and Colloids
Solute-Solvent interactions
"like dissolves like" the stronger the solute-solvent interaction, the greater the solubility of a solute in that solvent -polar solvents will dissolve polar and ionic solutes. -nonpolar solvents will dissolve nonpolar solutes.
polar molecules are soluble in
- polar solvents Ex. C2H5OH in H2O
Convert the concentration of 0.700 M Na₂SO₄ to g/mL
0.0994 g Na₂SO₄ / mL.
A solution is made using 100.5 g of water (MM = 18.02 g/mol) and 120.0 g of ethanol (MM = 46.07 g/mol). What is the mole fraction of the water in the solution?
0.68 m
What is the molarity of ions in a 0.738 M solution of KNO₃ assuming the compound dissociates completely?
1.48 M
What is the molality of ions in a 0.487 m solution of (NH₄)₃PO₄ assuming the compound dissociates completely?
1.95 m
A solution is made using 180.3 g of hexane (MM = 86.18 g/mol) and 200.0 g of octane (MM = 114.2 g/mol). What is the molality of the hexane in the solution?
10.46 m
A solution is made using 450.0 mL of isopropanol (density 0.7860 g/mL) and 617.5 mL of water (density 1.000 g/mL). What is the mass percent of the isopropanol?
36.42 %
A solution is made using 250.0 mL of phenol (density 1.070 g/mL) and 400.0 mL of water (density 1.000 g/mL). What is the molality phenol in water?
7.105 m (NOTE: since water is 1.000 g/mL, 400.0 mL = 400.0 g)
What is the molality of a 5.86 M ethanol (C2H5OH) solution whose density is 0.927 g/mL?
8.92 m
Solubility
A measure of how much solute can dissolve in a given solvent at a given temperature and pressure.
Micelle
A small particle is formed by aggregates of molecules with both polar and nonpolar segments (e.g., soap); the polar ends of these molecules point outward toward a polar solvent (e.g., water) while the non-polar ends will point inward toward a nonpolar solute (dirt/oil/grease). This allows the nonpolar substance to be washed away by the polar substance.
sol colloid
A sol is another name for a colloid that contains large solid particles that are evenly distributed through a fluid mixture. Paint has solid pigment that is mixed in with a fluid. Solid dispersed in liquid- paints and mud
The solubility of a salt in H₂O is 10 g/L at 25 °C. If you put 11 g of this salt in 1 L H₂O at 25 °C, the solution is: A) Saturated B) Unsaturated C) Supersaturated D) All of the above
A) Saturated When you put 11 g of salt in 1 L of 1H₂O, only 10 g can dissolve. When no additional salt can dissolve, the solution is said to be saturated.
Which of the following liquid pairs would be miscible? I. toluene (C₇H₈) and xylene (C₈H₁₀) II. water and ethanol (C₂H₅OH) III. water and xylene (C₈H₁₀) A) I only B) II only C) III only D) I and II E) II and III + Question 15 of 44
D) I and II It is helpful to recall 'like dissolves like." Toluene and xylene are both nonpolar and will be miscible. Water and ethanol are both polar, with hydrogen bonding, and will be miscible.
Density equation
D=m/V Density=mass/volume
Dilution
Decrease the concentration. Dilution is the process of decreasing the concentration of a solute in a solution, usually simply by mixing with more solvents like adding more water to the solution. To dilute a solution means to add more solvent without the addition of more solute
The _________ of the solution serves as a conversion factor between molality and molarity
Density
Relationship between density and concentration
Density measures the amount of mass per unit of volume in a substance. Concentration describes the amount of a substance dissolved in another substance. Changing the concentration of a solution changes the density of the solution. The higher the concentration, the denser the liquid.
Agitating solution
The movement of one or more components of a mixture to improve contact. it can make a substance dissolve faster in a solvent, by increases the contact between solvent and solute Ex. stirring.
like dissolves like
Two substances with similar intermolecular forces are likely to be soluble in each other.
Examples of solvents
Water ethanol, methanol, and acetone are the most common. rubbing alcohol, nail polish remover, oil, water, tetrachloroethylene, trichloroethane, trichloroethylene (TCE), Toluene, Acetone, Benzene
Hydrophobic
Water fearing
non-polar molecules are soluble in
non polar solvents Ex. CCl4 in C6H6
Osmotic Pressure (π)
opposing pressure required to prevent bulk transfer of solvent molecules through a semipermeable membrane. the pressure required to stop osmosis
ionic compounds are more soluble
polar solvents Ex. NaCl in H2O or NH3 (l)
The freezing point of a liquid will change when a solute is added. b. When an electrolyte solution (such as NaCl) is added to ice, the ions have ______ with water molecules and thus ______the ability of the water molecules to form a solid ice structure. A) strong intermolecular interactions; increase B) strong intermolecular interactions; decrease C) no intermolecular interactions; do not impact D) weak intermolecular interactions; increase E) weak intermolecular interactions; decrease + Question 42.b of 44
B) strong intermolecular interactions; decrease - When an electrolyte solution (such as NaClNaCl) is added to ice, the ions have strong intermolecular interactions with water molecules and, thus, decrease the ability of the water molecules to form a solid ice structure. A strong intermolecular attraction between the ions and water can prevent water molecules from packing tightly with each other.
Osmotic Pressure equation
π = iMRT
Colloid versus Solution
•colloidal particles are much larger than solute molecules •colloidal suspension is not as homogeneous as a solution •colloids exhibit the Tyndall effect
c. CaCl₂ is often used to melt ice on sidewalks. Calcium chloride is more effective at melting ice than NaCl. Choose the best explanation for this observation. A) CaCl₂ is a weak electrolyte and will not dissociate like NaCl. B) CaCl₂ dissociates into three ions increasing the concentration of solute species in solution. C) CaCl₂ is a strong acid and will donate a H⁺ to form hydronium ion in the water. D) CaCl₂ is a strong base and will deprotonate the water forming a basic solution. + Question 42.c of 44
B) CaCl₂ dissociates into three ions increasing the concentration of solute species in solution. CaCl2CaClX2 dissociates into three ions increasing the concentration of solute species in solution. The ions have strong intermolecular interactions with water molecules and, thus, decrease the ability of the water molecules to pack tightly with each other. The more ions present, the harder it is to crystallize water into ice.
Which one of the following is the correct dissociation equation for Li₂CO₃? A) Li⁺(aq) + CO₃²⁻ (aq) → Li₂CO₃ (s) B) Li₂CO₃ (s) → 2 Li⁺(aq) + CO₃²⁻ (aq) C) Li₂CO₃ (s) → Li⁺(aq) + CO₃²⁻ (aq) D) Li₂CO₃ (s) → Li⁺(aq) + C⁴⁻ (aq) + 3 O²⁻ (aq) + Question 8 of 44
B) Li₂CO₃ (s) → 2 Li⁺(aq) + CO₃²⁻ (aq) Lithium forms ions with a +1 charge. There are two lithium ions for every one carbonate ion. Carbonate has a -2 charge.
The ions formed when MgI₂ dissociates in water are A) Mg²⁺ and I²⁻ B) Mg²⁺ and I⁻ C) Mg⁺ and I⁻ D) Mg⁺ and I²⁻ E) Mg⁺ and I₂⁻ + Question 9 of 44
B) Mg²⁺ and I⁻. MgI₂ dissociates into Mg2++ and I− . The charges on the atoms can be determined by the number of electrons in their valence shells. Magnesium, Mg, is in Group 2 and loses 2 valence electrons to have a +2 charge. Iodine, I, is in Group 17 and has 7 valence electrons. Iodine will gain an electron to have take on a -1 charge.
Unsaturated solution
Contains less solute than the solvent has the capacity to dissolve at a specific temperature. An unsaturated solution is a solution that contains less than the maximum amount of solute that is capable of being dissolved. for example, water with just a pinch of salt or coffee with only one packet of sugar.
Based only on intermolecular forces, which of the following would be the least soluble in CH₃CH₂OH? A) CH₃OCH₃ B) H₂O C) CH₃CH₃ D) CH₃OH + Question 2 of 44
C) CH₃CH₃ Molecules with a C-O or O-H bond can experience both dipole-dipole and hydrogen bonding interaction with CH₃CH₂OH while CH₃CH₃ can only experience dispersion forces, so CH₃CH₃ will be the least soluble in CH₃CH₂OH.
The ions formed when Sr(C₂H₃O₂)₂ dissociates in water are A) Sr²⁺, C⁴⁻, H⁺, and O²⁻ B) Sr+ and C₂HO₂²⁻ C) Sr²⁺ and C₂H₃O₂⁻ D) Sr²⁺ and C₂HO₂²⁻ E) No ions form as Sr(C₂H₃O₂)₂ does not dissociate. + Question 10 of 44
C) Sr²⁺ and C₂H₃O₂⁻ The chemical formula shows that there are two C₂H₃O₂ ions for every Sr ion. Sr is found in Group 2 and will have a +2 charge in its ion form. This indicates that the C₂H₃O₂ has a charge of -1.
The freezing point of a liquid will change when a solute is added. Explain how the addition of salt impacts the boiling point of water. a. What is the strongest intermolecular force between two molecules of water in ice? A) ion-ion B) ion-dipole C) hydrogen bonding D) dipole-induced dipole E) London Dispersion forces + Question 42.a of 44
C) hydrogen bonding- The strongest intermolecular force between two water molecules is hydrogen bonding. The oxygen is a hydrogen bond acceptor and the hydrogen bonded to the oxygen is a hydrogen bond donor.
Concentration
Concentration is the removal of solvent, which increases the concentration of the solute in the solution. Concentration is the process of increasing the concentration of solutes in a solution. In other words, it is either decreasing the amount of solvent or increasing the amount of solutes.
Solvent
Is the substance present in the larger amount
Solute
Is(are) the substance(s) present in the smaller amount(s). A substance that is dissolved in a solution.
Concentration Units
Molality (m), Molarity (M), Mole Fraction (X), and Percent by Mass.
What is the molality of lithium ions in a 0.302 m solution of Li₃PO₄ assuming the compound dissociates.completely?
The correct answer is 0.906 mol Li / kg solvent.
Examples of solutions
Salt and Water, Sugar and Water, Tea and Water-seawater (solid and liquid), soda (gas and liquid) alcoholic beverages (liquid and liquid), air (gas and gas) blood (solid, gas, and liquid)
How many moles of Na₂SO₄ are in a 0.140 m aqueous solution that was prepared with 2.30 kg of water?
The correct answer is 0.322 mol Na₂SO₄.
Saturated Solution
a mixture that contains as much (the max) dissolved solute as is possible at a given temperature. For example chocolate milk - chocolate powder added to milk can create saturation at the point that no more powder can be added
Percent by Mass
a percentage determined by the ratio of the mass of each element to the total mass of the compound
Semipermeable membrane
allows the passage of solvent molecules but blocks the passage of solute molecules.
amphiphilic
molecule possessing a polar or charged area and a nonpolar or uncharged area capable of interacting with both hydrophilic and hydrophobic environments. is a chemical compound possessing both hydrophilic and lipophilic properties.
Molality (m)
moles of solute/kg of solvent
Molarity (M)
moles of solute/liters of solution
Mole Fraction (X)
concentration unit is defined as the ratio of the molar amount of a mixture component to the total number of moles of all mixture components
Soap molecules
contain nonpolar end that dissolves in nonpolar fats and oils and a polar end that dissolves in water. also encapsulates grease with their nonpolar ends, and faces the outside water environment with their polar ends. this structure is called MICELLE and is how soap dissolves grease ion water.
Supersaturated
contains more solute than is present in a saturated solution at a specific temperature. dissolved solute is more than the saturation point (for example, water with a cup of salt added or coffee with ten packets of sugar)
Miscible
describes liquids that dissolve in one another in all proportions
Immiscible
describes two or more liquids that do not mix with each other
A colloid formed between two liquids is known as a(n) A) sol B) emulsion C) foam D) aerosol
emulsion- a colloidal mixture of two or more liquids that normally do not mix.
Colloid
is a dispersion of particles of one substance throughout a dispersing medium of another substance. It is a heterogeneous mixture containing small, undissolved particles that do not settle out.
Solution
is a homogenous mixture of 2 or more substances
Density
is a word we use to describe how much space an object or substance takes up (its volume) in relation to the amount of matter in that object or substance (its mass). Another way to put it is that density is the amount of mass per unit of volume. If an object is heavy and compact, it has a high density
Osmosis
is the selective passage of solvent molecules through a porous membrane from a dilute solution to a more concentrated one. During osmosis, the solvent moves from the solution that is lower in solute concentration to the solution that is higher in solute concentration.
3 types of solutions
saturated unsaturated and supersaturated. A bottle of soda is a good way to visualize unsaturated, saturated and supersaturation solutions. Before the bottle of soda is opened, it's supersaturated with carbon dioxide. When you open the bottle, the excess carbon dioxide escapes with bubbles and gas, making the solution saturated. Once the soda has gone flat and uncarbonated, it's unsaturated with carbon dioxide.
Three types of interactions in the solution process
solvent-solvent interaction, solute-solute interaction, solvent-solute interaction.
Examples of solutes
sugar, salt, sand, dye, baking soda, flour
When NaCl dissolves in water
the Na+ ions are attracted to the partially negative oxygen atoms of the water molecules NaCl dissolves in water to form an Na+ and a Cl−. The Na+ is attracted to the negatively charged oxygen atom in water.
The mole To find moles To find mass to Find molar mass
the SI base unit used to measure the amount of a substance To find Moles= mass (g) / molar mass (g/mol) To Find mass= mol x molar mass (g/mol) To find Molar mass= look at the periodic table.
Solute-solute interactions
the intermolecular attractions between a solute particle and another solute particle
solvent-solvent interaction
the intermolecular attractions between a solvent particle and another solvent particle
Hydrophilic
water loving
