Chemistry Ch 8

what is the percent-by-mass concentration of sucrose (table sugar) in a solution made by dissolving 7.6 g of sucrose in 83.4 g of water?

(7.6 g sucrose)/(7.6 g sucrose + 83.4 g water) x 100 = 8.4%

one mole of solute particles lowers the freezing point of one kilogram of water by...

1.86 degrees Celsius

a solution is prepared by dissolving 10.0 g of glucose in enough water to give 325 mL of solution; what is the mass-volume percent concentration of glucose in the solution?

(10.0 g solute)/(325 mL solution) x 100 = 3.08% m/v

a 125-mL sample of mouthwash contains 12 mL of ethyl alcohol; what is the percent-by-volume concentration of ethyl alcohol in mouthwash?

(12 mL)/(125 mL) x 100 = 9.6% v/v

what is the osmolarity of 2 M in NaCl and 1 M in glucose?

(2 M x 2) + (1 M x 1) = 5 osmol

what is the osmolarity of 2 M in both NaCl and glucose?

(2 M x 2) + (2 M x 1) = 6 osmol

a 100-mL sample of 5.0% alcohol-in-water solution contains...

5.0 mL of alcohol dissolved in enough water to give 100 mL of solution (5 mL alcohol and 95 mL water)

solution

A homogeneous mixture of two or more substances with each substances retaining its own chemical identity

determine the molarity of 20.0 g of NaOH dissolved in enough water to give 1.50 L of solution

NaOH = 40.0 g per mole (20.0 g NaOH) x (1 mole NaOH/40.00 g NaOH) = 0.500 mole NaOH M = (0.500 mole NaOH/1.50 L solution) = 0.333 mole NaOH/L solution

when RBCs are placed in physiological saline solution (0.92% m/v) sodium chloride solution, water flow is _________

balanced; neither hemolysis nor crenation occurs

solution formation occurs more rapidly at higher temperatures bc molecules of a. solute, but no solvent, move more rapidly b. solvent, but not solute, move more rapidly c. both solute and solvent move more rapidly d. no correct response

c.

the defining equation for percent-by-volume concentration is a. (volume solute + volume solution) x 100 b. (volume solute x volume solution) x 100 c. (volume solute/volume solution) x 100 d. no correct response

c.

the osmolarity of a 0.40 molar NaCl solution is a. 0.20 b. 0.40 c. 0.80 d. no correct response

c.

the percent concentration unit most often encountered in a hospital (medical) setting is a. percent by mass b. percent by volume c. mass-volume percent d. no correct response

c.

the rule "like dissolves like" is not adequate when predicting solubility in water when the solute is a(n) a. nonpolar gas b. polar liquid c. ionic solid d. no correct response

c.

when 60.0 mL of a 1.00 M solution is diluted by adding 30.0 mL of water, the amount of solute present a. increases b. decreases c. remains the same d. no correct response

c.

when an ionic solute dissolves in water, the water molecules hydrate a. positive ions but not negative ions b. negative ions but not positive ions c. both positive ions and negative ions d. no correct response

c.

which of the following solutions is hypertonic with respect to RBCs? a. 2.0% m/v glucose b. 4.0% m/v glucose c. 6.0% m/v glucose d. no correct response

c.

which of the following solutions would have a lower freezing point than a solution containing 0.20 mole of glucose per kilogram of solvent? a. solution containing 0.10 mole of glucose per kg of solvent b. solution containing 0.10 mole of NaCl per kg of solvent c. solution containing 0.10 mole of MgCl2 per kg of solvent d. no correct response

c.

suspension

heterogeneous mixture that contains dispersed particles that are heavy enough that they settle out under the influence of gravity

only mixtures that are _________ are solutions

homogeneous

two types of mixtures

homogeneous and heterogeneous

colloidal dispersion

homogeneous mixture that contains dispersed particles that are intermediate in size between those of a true solution and those of an ordinary heterogeneous mixture -mixtures in which a material is dispersed rather than dissolved

two types of pure substances

elements and compounds

predict if AgCl (an ionic solid) is soluble in water

insoluble; silver (Ag), lead (Pb), and mercury (Hg) are the exceptions to being soluble in chloride

predict if methane (a nonpolar gas) is soluble in water

insoluble; they are of unlike polarity bc water is polar

a solution w/ high osmotic pressure will take up more water than a solution of...

lower osmotic pressure

adding a nonvolatile solute to a solvent ______ the freezing point of the resulting solution below that of the pure solvent

lowers

adding a nonvolatile solute to a solvent ________ the vapor pressure of the resulting solution below that of the pure solvent at the same temperatuer

lowers

mass of solution = ________ + _________

mass of solute + mass of solvent

example of colligative properties

vapor-pressure lowering boiling-point elevation freezing-point depression osmotic pressure

predict if AgNO3 (an ionic solid) is soluble in water

soluble; all compounds containing the nitrate ion (NO3-) are soluble

predict if Na2SO4 (an ionic solid) is soluble in water

soluble; all ionic sodium-containing compounds are soluble

predict if ethyl alcohol (a polar liquid) is soluble in chloroform (a polar liquid)

soluble; both substances are polar, so they should be relatively soluble in one another - like dissolves like

hemolysis

swelling up and rupture of red blood cells -caused by an increase in the amount of water entering the cells compared with the amount of water leaving the cells

Henry's Law

the amount of gas that will dissolve in a liquid at a given temperature is directly proportional to the partial pressure of the gas above the liquid

concentration

the amount of solute present in a specified amount of solution

solute

a component of a solution that is present in a lesser amount relative to that of the solvent

unsaturated solution

a solution that contains less than the maximum amount of solute that can be dissolved under the conditions at which the solution exists -most commonly encountered solution

saturated solution

a solution that contains the maximum amount of solute that can be dissolved under the conditions at which the solution exists

hypertonic solution

a solution with a higher osmotic pressure than that within the cell -RBCs undergo crenation (water flows out of the cells bc solute concentration is greater outside the cell)

isotonic solution

a solution with an osmotic pressure that is equal within the cells

what is the freezing point of an aqueous solution that contains 3.00 moles of the ionic solute CaCl2 (a deicing compound) per one kilogram of water?

*formula unit of CaCl2 dissociates to three ions* (3.00 moles CaCl2) x (3 moles particles/1 mole CaCl2) x (1.86 degrees Celsius/1 mole particles) = 16.7 degrees Celsius -0.0 C - 16.7 C = -16.7 degrees Celsius

what is the boiling point of a solution that contains 0.25 mole of the ionic solute NaBr per one kilogram of water?

*formula units of NaBr will dissociate to produce 2 ions* (0.25 mole NaBr) x (2 moles particles/1 mole NaBr) x (0.51 C/1 mole particles) = 0.26 degrees Celsius 100.00 C + 0.26 C = 100.26 C

normal saline solution that is used to dissolve drugs for intravenous use is 0.92% m/v NaCl in water; how many grams of NaCl are required to prepare 35.0 mL of normal saline solution?

-given: 35.0 mL solution -desired: g of NaCl -given concentration is 0.92%, which means 0.92 g of NaCl per 100 mL of solution -(35.0 mL solution) x (0.92 g NaCl/100 mL solution) = 0.32 g NaCl

how many grams of sucrose must be added to 375 g of water to prepare a 2.75% m/m solution of sucrose?

-given: 375 g of water (solvent) -desired: grams of sucrose (solute) -in a 2.75%-by-mass sucrose solution, there are 2.75 g of sucrose for every 97.25 g of water (100 g of solution - 2.75 g sucrose = 97.25 g water) (375 g water) x (2.75 g sucrose/97.25 g water) = 10.6 g sucrose

what is the mass-volume percent glucose concentration in blood plasma if the glucose concentration is known to be 92 mg/dL?

-given: 92 mg glucose/1 dL solution -desired: g glucose/100 mL of solution (92 mg glucose/1 dL solution) x (10^-3 g glucose/1 mg glucose) x (1 dL solution/100 mL solution) = 0.092 g glucose/100 mL solution (0.092 %)

effect of pressure on solubility

-has little effect on the solubility of solids and liquids in water -as the pressure of gas above a liquid increases, the solubility of the gas increases (Henry's Law)

suspension properties

-heterogeneous -very large particles, which are often visible -not transparent -particles settle rapidly -particles can be filtered out

solution properties

-homogeneous -atoms, ions, and small molecules -transparent -particles do not settle -particles cannot be filtered out

colloidal dispersion properties

-homogeneous -groups of small particles or individual larger molecules -scatters light (Tyndall effect) -particles do not settle -particles cannot be filtered out

when an ionic solid, such as sodium chloride, dissolves in water, the water molecules ________ the ions

-hydrate (the positive ions are bound to the water molecules by their attractions for fractional negative charge on the water's oxygen atom, and the negative ions are bound to the water molecules by their attraction for the fractional positive charge on the water's hydrogen atoms)

a nurse wants to prepare a 1.0% m/v silver nitrate solution from 24 mL of a 3.0% m/v stock solution of silver nitrate; how much water should be added to the 24 mL of stock solution?

-initial volume = 24 mL -final volume = ? Vd = (3.0% x 24 mL)/1.0% = 72 mL solvent added: 72 - 24 = 48 mL

effect of temperature on solubility

-most solids become more soluble in water with increasing temperature -most gases become less soluble in water with increasing temperature

1 mole of glucose produces ___ mole of particles (molecules) since molecular solutes remain in molecular form in solution

1

one mole of any molecular solute raises the boiling point of one kilogram of water by _____ degrees Celsius

0.51 degrees Celsius

particles of the dispersed phase in a colloidal dispersion are so small that they

1. are not usually discernible by the naked eye 2. do not settle out under the influence of gravity 3. cannot be filtered out using filter paper that has relatively large pores

two types of interparticle interactions that must be overcome for a solute to dissolve in a solvent

1. attractions between solute particles (solute-solute attractions) 2. attraction between solvent particles (solvent-solvent attractions)

6 general properties of solutions

1. contains two or more components: a solvent and one or more solutes 2. has a variable composition; that is, the ratio of solute to solvent may be varied 3. properties change as the ratio of solvent to solute is changed 4. dissolved solutes are present as individual particles (molecules, atoms, or ions) - intermingling of components at the particle level is a requirement for homogeneity 5. solutes remain uniformly distributed throughout the solution and will not settle out with time; every part of a solution has exactly the same properties and composition as every other part 6. solutes generally can be separated from the solvent by physical means such as evaporation

three ways percent concentration may be indicated

1. percent by mass (or mass-mass percent) 2. percent by volume (or volume-volume percent) 3. mass-volume percent

three factors that affect the rate of solution formation

1. state of subdivision of the solute: a crushed aspirin tablet will dissolve in water more rapidly than a whole aspirin tablet; the more compact whole aspirin tablet has less surface area, and thus fewer solvent molecules can interact with it at a given time 2. degree of agitation during solute preparation: stirring solution components disperses the solute particles more rapidly, increasing the possibilities for solute-solvent interactions; hence the rate of solution formation is increased 3. temperature of the solution components: solution formation occurs more rapidly as the temp is increased; at a higher temp, both solute and solvent molecules move more rapidly, so more interactions between them occur within a given time period

the net transfer of solvent across the membrane continues until...

1. the concentrations of solute particles on both sides of the membrane become equal 2. the hydrostatic pressure on the concentrated side of the membrane becomes sufficient to counterbalance the greater escaping tendency of molecules from the dilute side

a volume of one deciliter is equivalent to a volume of ____ milliters

100 -1 deciliter = 10^-1 liter = 100 milliliters -thus a solute concentration of 1 g/dL is equivalent to a 1% m/v concentration (1 g/dL = 1 g/100 mL = 1% m/v)

1 mole of NaCl produces __ moles of particles (ions) since soluble ionic solutes dissociate into ions

2

what is the osmolarity of 2 M glucose?

2 M x 1 = 2 osmol

what is the osmolarity of 2 M of NaCl?

2 M x 2 = 4 osmol

what is the osmolarity of 2 M CaCl2?

2 M x 3 = 6 osmol

a 2.3% solution of any solute contains...

2.3 g of solute in 100 mL of solution

1 moles of CaCl2 produces ___ moles of particles (ions) when dissociation occurs

3

a solution whose mass percent concentration is 5.0% would contain...

5.0 g of solute per 100.0 g of solution (5.0 g of solute and 95.0 g of solvent)

solvent

The component of a solution that is present in the greatest amount -the medium in which the other substances present is dissolved

semipermable membrane

a membrane that allows certain types of molecules to pass thru it but prohibits the passage of other types of molecules -selectivity is based on size of molecules

colligative property

a physical property of a solution that depends only on the number of solute particles (molecules or ions) present in a given quantity of solvent and not on their chemical identities

nonaqueous solution

a solution in which a substance other than water is the solvent ex: alcohol based solutions

aqueous solution

a solution in which water is the solvent

dilute solution

a solution that contains a small amount of solute relative to the amount that could dissolve

adding a nonvolatile solute to a pure solvent produces which of the following effects? a. vapor-pressure lowering b. freezing-point elevation c. boiling point depression d. no correct response

a.

chlorides, bromides, and iodides are soluble in water except for those of a. silver, lead, and mercury b. lithium, sodium, and potassium c. ammonium, magnesium, and calcium d. no correct response

a.

for which of the following types of mixtures do the particles present scatter light? a. colloidal dispersion b. true solution c. suspension d. no correct response

a.

if 200.0 mL of a 0.40 M NaCl solution is diluted with water to form 800.0 mL of solution, the molarity of the new solution is a. 0.10 M b. 0.20 M c. 0.80 M d. no correct response

a.

in the process of osmosis, solvent passes thru a semipermeable membrane a. from a dilute solution to a more concentrated solution b. from a concentrated solution to a more dilute solution c. in only one direction d. no correct response

a.

the number of grams of NaCl present in 10.0 g of a 1.00% m/m NaCl solution is a. 0.100 g b. 1.00 g c. 10.0 g d. no correct response

a.

the percent by mass concentration of a solution containing 5.0 g of NaCl in 500.0 g of solution is a. 1.0% m/m b. 5.0% m/m c. 10.0 % m/m d. no correct response

a.

the word "like" in the solubility rule "like dissolves like" refers to a. like polarity b. like physical state c. like boiling point d. no correct response

a.

when RBCs are placed in a hypotonic solution a. hemolysis occurs b. crenation occurs c. cells shrink in size d. no correct response

a.

which of the following statements concerning a saturated solution is incorrect? a. undissolved solute must be present b. undissolved solute may or may not be present c. undissolved solute, if present, is in equilibrium with dissolved solvent d. no correct response

a.

as the number of solute particles increases, the reduction in vapor pressure __________

also increases (the solute molecules take up room on the surface of the liquid)

hydrated ion

an ion in solution that is surrounded by water molecules

supersaturated solution

an unstable solution that temporarily contains more dissolved solute than that present in a saturated solution

a 0.200 M solution of NaCl which contains 0.200 mole of NaCl would have a volume of a. 0.100 L b. 1.00 L c. 10.0 L d. no correct response

b.

a 2.0% m/v NaCl solution contains 2.0 g of NaCl per a. 100.0 g solution b. 100.0 mL solution c. 1000 g solution d. no correct response

b.

for which of the following types of ionic compounds are most examples insoluble in water? a. nitrates b. phosphates c. acetates d. no correct response

b.

if 100.0 mL of 8.0 M NaCl solution is diluted with water to form a 4.0 M solution; what is the volume in mL, of the new solution? a. 400.0 mL b. 200.0 mL c. 50.0 mL d. no correct response

b.

if addition of a small crystal of NaCl to an NaCl solution causes additional crystals to form, then the original solution was a. unsaturated b. supersaturated c. satruated d. no correct response

b.

in general, the solubilities of gaseous solutes in water a. increase with increasing temperature b. increase with increasing pressure c. are independent of temperature and pressure changes d. no correct response

b.

the dL volume unit is equivalent to a. 10 mL b. 100 mL c. 10 L d. no correct response

b.

the defining equation for the molarity concentration unit is a. moles solute/mL solution b. moles solute/L solution c. grams solute/L solution d. no correct response

b.

the numerical value for a colligative property is dependent on the a. identity of the solute present b. number of solute particles present c. the boiling point of the solute present d. no correct response

b.

what is the freezing point for a solution containing 1.00 mole of glucose (a nondissociating solute) dissolved in 1.00 kg water? a. +1.86 C b. -1.86 C c. -0.51 C d. no correct response

b.

which of the following is a characteristic of a suspension? a. it is a homogeneous mixture b. filters remove most suspended particles c. appears transparent to a beam of light d. no correct response

b.

which of the following solutions is isotonic with respect to RBCs? a. 0.20 M lactose b. 0.28 M lactose c. 0.35 M lactose d. no correct response

b.

which of the following statements about solutions is incorrect? a. solutions in which both solute and solvent are in the solid state are not possible b. solutions readily separate in to solute and solvent if left undisturbed for 24 hours c. solutions can contain more than one solute d. no correct response

b.

adding a solute to a pure solvent causes the solvent's physical properties to _________

change

concentration of stock solution x volume of stock solution =

concentration of diluted solution x volume diluted solution -Cs x Vs = Cd x Vd

a colloidal dispersion differs from a true solution in that colloidal particles a. settle rapidly b. are large enough to be seen with the naked eye c. are large enough to be removed by most filters d. no correct response

d.

for which of the following solutions is the concentration 1.0 molar? a. 3.0 moles of solute in 1.5 L of solution b. 2.0 moles solute in 500.0 mL solution c. 1.0 mole solute in 100.0 mL solution d. no correct response

d.

in a solution containing 15 mL of water and 25 mL of isopropyl alcohol a. the water is the solvent b. the alcohol is the solute c. both eh water and alcohol are considered to be solvents d. no correct response

d.

which of the following does not affect the rate at which a solute dissolves in a solvent? a. state of subdivision of a solute b. temperature of the solvent c. stirring during the dissolving process d. no correct response

d.

which of the following is not a general property of solutions? a. they are homogeneous mixtures b. they have a variable composition c. solutes remain uniformly distributed throughout the solution d. no correct response

d.

determine the molarity of 4.35 moles of KMnO4 dissolved in enough water to give 750 mL of solution

given: moles of solute = 4.35 moles 750 mL solution = 0.750 L solve: M = (4.35 moles KMnO4/0.750 L solution) = 5.80

a typical does of iron (II) sulfate (FeSO4) used in the treatment of iron-deficiency anemia is 0.35 g; how many milliliters of a 0.10 M iron (II) sulfate solution would be needed to supply this dose?

given: 0.35 g of FeSO4 desired: milliliters of FeSO4 0.35 g FeSO4 x (1 mole FeSO4/151.92 g FeSO4) x (1 L solution/0.10 mole FeSO4) x (1000 mL solution/1 L solution) = 23 mL solution

how many g of sucrose (C12H22O11) are present in 185 mL of a 2.50 M sucrose solution?

given: 185 mL solution desired: g of sucrose 185 mL solution x (1 L/1000 mL) x (2.50 moles sucrose/1 L of solution) x (324.34 g sucrose/1 mole sucrose) = 158 g sucrose

all solutions whose total solute concentration is 0.28 M are _________

isotonic to RBCs

_____ pressure should be applied to prevent osmosis

more

nonvolatile

not easily vaporized

it is the total number of __________ present in a solution that determine the magnitude of the colligative property effect

particles

when a percent concentration if given without specifying which of the three types of percent concentration it is, it is assumed to be...

percent by mass -a 5% NaCl solution is assumed to be a 5% m/m NaCl solution

dilution

process in which more solvent is added to a solution in order to lower its concentration

all samples of matter are either

pure substances or mixtures

adding a nonvolatile solute to a solvent ________ the boiling point of the resulting solution above that of the pure solvent

raises

crenation

shrinking of red blood cells -occurs bc the osmotic pressure of the concentrated salt solution is greater than that of the fluid within the cells

concentrated solution

solution that contains a large amount of solute relative to the amount that could dissolve -does not have to be a saturated solution

hypotonic solution

solution with a lower osmotic pressure than that within the cells -RBCs hemolyze (water flows in bc solute concentration is greater within the cell)

Tyndall effect

the light-scattering phenomenon that causes the path of a beam to visible light through a colloidal dispersion to be observable

mass-volume percent

the mass of solute in a solution (in grams) divided by the total volume of solution (in milliliters) multiplied by 100 -used when the solute in solid and the solvent is liquid -indicated the number of g of solute dissolved in 100 mL of solution -unit: m/v (mass in grams, volume in mL or L)

percent by mass

the mass of solute in a solution divided by the total mass of solution, multiplied by 100 -the mass of solute and solution MUST be measured in the same unit (usually grams) -gives g of solute per 100 g of solution -unit: m/m

solubility

the maximum amount of a solute that can be dissolved in a given amount of solvent at given conditions -expressed as grams of solute per 100 g of solvent

molarity (M)

the moles of solute in a solution divided by the liters of the solution -volume MUST be in L

osmosis

the passage of a solvent thru a semipermeable membrane separating a dilute solution (or pure solvent) from a more concentrated solution

osmotic pressure

the pressure that must be applied to prevent the net flow of solvent thru a semipermeable membrane from a solution of lower solute concentration to a solution of higher solute concentration

oxmolarity

the product of a solution's molarity and the number of particles produced per formula unit if the solute dissociates -osmolarity = molarity x i -i = number of particles produced from the dissociation of one formula unit of solute

what happens when there is an excess of undissolved solute in a saturated solution?

the saturated solution enters equilibrium where an amount of undissolved solute is continuously dissolving while an equal amount of dissolved solute in continuously crystallizing

percent by volume

the volume of solute in a solution divided by the total volume of solution, multiplied by 100 -used where the solute and solvent are both liquids or both gases -gives mL of solute per 100 mL of solution -unit: v/v

t or f: a beam of light passing through a true solution cannot be seen bc the light is not being scattered

true

t or f: a beam of light passing thru a colloidal dispersion can be observed bc the light is scattered by the dispersed phase

true

t or f: generally, solutions are transparent

true

t or f: in a saturated solution, the dissolved solute is in dynamic equilibrium with the undissolved solute

true

t or f: more than one solute can be present in a solution

true

t or f: substances of similar polarity tend to be more soluble in each other than substances that differ in polarity

true

t or f: that greater the difference in solute-solvent polarity, the less soluble the solute

true

t or f: the solutes are the active ingredients in the solution and are the substances that undergo reaction when solutions are mixed

true

t or f: water always moves in the direction of greater osmotic pressure

true

t or f: water molecules are polar

true