Multiple Choice Questions

When do you use the percent by volume to find the concentration?
  • agitating the solution
  • agitation, temperature, particle size of teh solute
  • when both the solute and the solvent are liquids
  • temperature and the nature of solute and solvent
How can concentration by expressed quantitatively?
  • in molarity
  • supersaturation
  • the solubility decreases
  • pH = - log [H +]
What are two ways of expressing the ratio of solute to solvent in a solution?
  • The magnitudes of the freezing point depression and the boiling point elevation of a solution are directly proportional to the molal concentration (m), assuming the solute is molecular, not ionic.
  • Chemists use two ways to express the ratio of solute particles to solvent particles: in molality and in mole fractions
  • molarity, percent by volume, percent by mass
  • the increase of kinetic energy causes the particles of the solvent to collide with the particles of the solute, this causes the solute to break apart and dissolve faster
solubility
  • the amount of solute that dissolves in a given quantity of a solvent at a specified temperature and pressure to produce a saturated solution
  • a solution that contains the maximum amount of solute for a given quantity of solvent at a constant temperature and pressure
  • the ratio of the concentration of the dissociated form of an acid to the concentration of the undissociated form
  • the ratio of the concentration fo the conjugate acid times the concentration of the hydroxide ion to the concentration of the base
Examine the factors that determine the mass of a solute that will dissolve in a given mass of solvent.
  • M = (0.90g NaCl)/(100 mL) (1 mol NaCl)/(58.5g NaCl) (100 mL)/(1 L)M = (0.90)/(100) (1 mol NaCl)/(58.5) (100)/(1 L)M = 0.15 mol/L=0.15M
  • The magnitudes of the freezing point depression and the boiling point elevation of a solution are directly proportional to the molal concentration (m), assuming the solute is molecular, not ionic.
  • temperature affects the solubility of a solid solutes in a solvent; both temperature and pressure affect the solubility of gaseous solutes in a solvent. This means that temperature and pressure affect how much of a solute will dissolve in a solvent.
  • the increase of kinetic energy causes the particles of the solvent to collide with the particles of the solute, this causes the solute to break apart and dissolve faster
How many milliliters of alcohol are in 167 mL of an 85.0% (v/v) alcohol solution?
  • 5.0 mL
  • in molarity
  • 142 mL
  • 0.18M
What is the pH of a solution with a hydrogen-ion concentration of 4.2 * 10 ^-10 ?
  • pH = - log [H +]6.35 = - log [H +]log[H +] = -6.35[H +] = antilog(-6.35)[H +] = 4.5 * 10 ^-7 M
  • pH = - log [H +]pH = - log [4.2 * 10 ^-10]pH = -(-9.38)pH = 9.38
  • when both the solute and the solvent are liquids
  • ∆T(sub)b = K(sub)b m = 0.512˚C/m 3.00m = 1.54˚CT(sub)b = 100˚C + 1.54˚C
base dissociation constant (K(sub)b)
  • the ratio of the concentration of the dissociated form of an acid to the concentration of the undissociated form
  • the increase of kinetic energy causes the particles of the solvent to collide with the particles of the solute, this causes the solute to break apart and dissolve faster
  • the ratio of the concentration fo the conjugate acid times the concentration of the hydroxide ion to the concentration of the base
  • to calculate the molarity of a solution, divide the number of moles of the solute by the volume of the solution in litersMolarity (M) = moles of solute / liters of solution
unsaturated solution
  • a solution that contains the maximum amount of solute for a given quantity of solvent at a constant temperature and pressure
  • a solution that contains less solute that a saturated solution at a given temperature and pressure
  • a solution in which [H +] is one less than [OH -][H +] is less than 1*10 ^-7 M
  • a solution that contains a relatively small amount of solute
What does NOT change when a solution is diluted by the addition of solvent?
  • 10 mol of solute / 1 L of solution
  • number of moles of solute
  • grams of solute per 100 grams of solvent
  • the solubility decreases
molal freezing-point depression constant (K(sub)f)
  • temperature affects the solubility of solid, liquid, and gaseous solutes in a solvent; both temperature and pressure affect the solubility of gaseous solutes
  • a solution that contains a solute that is nonvolatile (not easily vapourised) always has a lower vapour pressure than the pure solvent; in an aqueous solution, within the liquid and at the surface, ions are surrounded by layers of associated water molecules, or shells of water of solvation, the formation of these shells decreases number of solvent molecules that have enough kinetic energy to escape as vapour. Ionic solutes that dissociate have greater effects on vapour pressure, because the vapour pressure is affected by the number of particles and the ions in ionic compounds split up when dissolved
  • dissolving occurs at the surface of solute, agitation (stirring or shaking) continuously brings fresh solvent into contact with the solute; this speeds of dissolving
  • a constant that is equal to the change in freezing point for a 1-molal solution of a nonvolatile molecular soluteT(sub)f = K(sub)f * m (molality)
molarity (M)
  • the amount of solute that dissolves in a given quantity of a solvent at a specified temperature and pressure to produce a saturated solution
  • a property of solutions that depends only upon the number of solute particles, not upon their identity
  • the number of moles of solute dissolved in one liter of solution; molar concentration
  • the product of the concentrations of the hydrogen ions and hydroxide ionsK(sub)w = [H +] [OH -] = 1.0 10 ^-14
Henry's law
  • the amount of solute that dissolves in a given quantity of a solvent at a specified temperature and pressure to produce a saturated solution
  • dissolving occurs at the surface of solute, agitation (stirring or shaking) continuously brings fresh solvent into contact with the solute; this speeds of dissolving
  • a solution that contains less solute that a saturated solution at a given temperature and pressure
  • at a given temperature, the solubility (S) of a gas in a liquid is directly proportional to the pressure (P) of the gas above the liquidS1/P1 = S2/P2
Identify the units usually used to express the solubility of a solute.
  • grams of solute per 100g of solvent (g/100g); grams per liter of solution (g/L)
  • vapour-pressure lowering, freezing-point depression, and boiling point elevation
  • Percent by volume (%(m/m)) = (mass of solute)/(mass of solution) * 100%
  • pH = - log [H +]pH = - log [4.2 * 10 ^-10]pH = -(-9.38)pH = 9.38
saturated solution
  • A solution with a pH less than 7.0 is acidic. A solution with a pH of 7.0 neutral. A solution with a pH greater than 7.0 is basic.
  • a solution that contains a relatively small amount of solute
  • a solution in which [H +] is one less than [OH -][H +] is less than 1*10 ^-7 M
  • a solution that contains the maximum amount of solute for a given quantity of solvent at a constant temperature and pressure
immiscible
  • H3O +, is the ion that forms when a water molecule gains a hydrogen ion
  • temperature and the nature of solute and solvent
  • grams of solute per 100 grams of solvent
  • liquids that are insoluble in one another
How are acids and bases classified as either strong or weak?
  • Acids and bases are classified as strong or weak based on the degree to which they ionise in water.
  • A solution with a pH less than 7.0 is acidic. A solution with a pH of 7.0 neutral. A solution with a pH greater than 7.0 is basic.
  • a constant that is equal to the change in freezing point for a 1-molal solution of a nonvolatile molecular soluteT(sub)f = K(sub)f * m (molality)
  • changes in pressure have little effect on the solubility of solids in liquids. gas solubility increases as the partial pressure of the gas above the solution increases
molality (m)
  • the ratio of the moles of the solute to the total number of moles of solvent and solute
  • the amount of solute that dissolves in a given quantity of a solvent at a specified temperature and pressure to produce a saturated solution
  • the number of moles of solute dissolved in one liter of solution; molar concentration
  • the number of moles of solute dissolved in 1 kilogram (1000 grams) of solvent; known as molal concentrationMolality (m) = moles of solute / kilogram of solvent
dilute solution
  • a solution that contains a relatively small amount of solute
  • any aqueous solution in which [H +] and [OH -] are equal
  • a solution that contains a large amount of solute
  • the ratio of the moles of the solute to the total number of moles of solvent and solute
concentrated solution
  • a solution that contains a large amount of solute
  • an acid that is completely ionised in aqueous solution
  • a solution that contains the maximum amount of solute for a given quantity of solvent at a constant temperature and pressure
  • agitation, temperature, particle size of teh solute
How does agitation affect dissolving?
  • dissolving occurs at the surface of solute, agitation (stirring or shaking) continuously brings fresh solvent into contact with the solute; this speeds of dissolving
  • the increase of kinetic energy causes the particles of the solvent to collide with the particles of the solute, this causes the solute to break apart and dissolve faster
  • changes in pressure have little effect on the solubility of solids in liquids. gas solubility increases as the partial pressure of the gas above the solution increases
  • the ratio of the concentration fo the conjugate acid times the concentration of the hydroxide ion to the concentration of the base
How does particle size of the solute affect dissolving?
  • the ratio of the concentration fo the conjugate acid times the concentration of the hydroxide ion to the concentration of the base
  • the smaller the particles are, the more surface area of the solute will be exposed to the solvent; this causes the solute to dissolve faster
  • the solubility of most solid substances increases as the temperature of the solvent increases; some solid substances decrease in solubility as the temperature of the solvent increases. the solubility of most gases are greater in cold water than in hot
  • dissolving occurs at the surface of solute, agitation (stirring or shaking) continuously brings fresh solvent into contact with the solute; this speeds of dissolving
weak acid
  • the ratio of the moles of the solute to the total number of moles of solvent and solute
  • an acid ionises only slightly in aqueous solution
  • contains more solute than it can theoretically hold at a given temperature
  • liquids that are insoluble in one another
percent by mass volume formula
  • Percent by volume (%(m/m)) = (mass of solute)/(mass of solution) * 100%
  • a solution that contains a large amount of solute
  • Either acid-base indicators of pH meters can be used to measure pH.
  • contains more solute than it can theoretically hold at a given temperature
What is boiling-point elevation?
  • changes in pressure have little effect on the solubility of solids in liquids. gas solubility increases as the partial pressure of the gas above the solution increases
  • dissolving occurs at the surface of solute, agitation (stirring or shaking) continuously brings fresh solvent into contact with the solute; this speeds of dissolving
  • the ratio of the concentration fo the conjugate acid times the concentration of the hydroxide ion to the concentration of the base
  • because adding a nonvolatile solute lowers the vapour-pressure of a solution, it takes more kinetic energy to raise the vapour pressure of the liquid, therefor, the boiling point is higher. The difference in temperature between the boiling point of a solution and the boiling point of the pure solvent is the boiling-point elevation
colligative property
  • a solution that contains less solute that a saturated solution at a given temperature and pressure
  • the product of the concentrations of the hydrogen ions and hydroxide ionsK(sub)w = [H +] [OH -] = 1.0 10 ^-14
  • a property of solutions that depends only upon the number of solute particles, not upon their identity
  • the number of moles of solute dissolved in one liter of solution; molar concentration
How can you describe the equilibrium in a saturated solution?
  • the solubility of most solid substances increases as the temperature of the solvent increases; some solid substances decrease in solubility as the temperature of the solvent increases. the solubility of most gases are greater in cold water than in hot
  • for aqueous solutions, the product of the hydrogen-ion concentratoin and the hydroxide-ion concentration equals 1.0 x 10 ^-14
  • in a saturated solution, a state of dynamic equilibrium exists between the solution and any undissolved solute, provided that the temperature remains constant
  • at a given temperature, the solubility (S) of a gas in a liquid is directly proportional to the pressure (P) of the gas above the liquidS1/P1 = S2/P2
How does pressure affect solubility?
  • The magnitudes of the freezing point depression and the boiling point elevation of a solution are directly proportional to the molal concentration (m), assuming the solute is molecular, not ionic.
  • changes in pressure have little effect on the solubility of solids in liquids. gas solubility increases as the partial pressure of the gas above the solution increases
  • dissolving occurs at the surface of solute, agitation (stirring or shaking) continuously brings fresh solvent into contact with the solute; this speeds of dissolving
  • the solubility of most solid substances increases as the temperature of the solvent increases; some solid substances decrease in solubility as the temperature of the solvent increases. the solubility of most gases are greater in cold water than in hot
percent by volume formula
  • contains more solute than it can theoretically hold at a given temperature
  • Percent by volume (%(m/m)) = (mass of solute)/(mass of solution) * 100%
  • a measure of the amount of solute that is dissolved in a given quantity of solvent
  • Percent by volume (%(v/v)) = (volume of solute)/(volume of solution) * 100%
What is vapour-pressure lowering?
  • the solubility of most solid substances increases as the temperature of the solvent increases; some solid substances decrease in solubility as the temperature of the solvent increases. the solubility of most gases are greater in cold water than in hot
  • a solution that contains less solute that a saturated solution at a given temperature and pressure
  • a solution that contains the maximum amount of solute for a given quantity of solvent at a constant temperature and pressure
  • a solution that contains a solute that is nonvolatile (not easily vapourised) always has a lower vapour pressure than the pure solvent; in an aqueous solution, within the liquid and at the surface, ions are surrounded by layers of associated water molecules, or shells of water of solvation, the formation of these shells decreases number of solvent molecules that have enough kinetic energy to escape as vapour. Ionic solutes that dissociate have greater effects on vapour pressure, because the vapour pressure is affected by the number of particles and the ions in ionic compounds split up when dissolved
What is freezing-point depression?
  • when a substance freezes, its particles take on an orderly pattern, the presence of a solute disrupts this pattern because of the shells of water of solvation, as a result, more kinetic energy must be withdrawn from a solution than a pure solvent to solidify; the difference in temperature between the freezing point of a solution and the freezing point of the pure solvent is called the freezing-point depression
  • The magnitudes of the freezing point depression and the boiling point elevation of a solution are directly proportional to the molal concentration (m), assuming the solute is molecular, not ionic.
  • a solution that contains a solute that is nonvolatile (not easily vapourised) always has a lower vapour pressure than the pure solvent; in an aqueous solution, within the liquid and at the surface, ions are surrounded by layers of associated water molecules, or shells of water of solvation, the formation of these shells decreases number of solvent molecules that have enough kinetic energy to escape as vapour. Ionic solutes that dissociate have greater effects on vapour pressure, because the vapour pressure is affected by the number of particles and the ions in ionic compounds split up when dissolved
  • the solubility of most solid substances increases as the temperature of the solvent increases; some solid substances decrease in solubility as the temperature of the solvent increases. the solubility of most gases are greater in cold water than in hot
molal boiling-point elevation constant (K(sub)b)
  • a constant that is equal to the change in freezing point for a 1-molal solution of a nonvolatile molecular soluteT(sub)f = K(sub)f * m (molality)
  • a constant that is equal to the change in boiling point for a 1-molal solution of a nonvolatile molecular soluteT(sub)b = K(sub)b * m (molality)
  • A solution with a pH less than 7.0 is acidic. A solution with a pH of 7.0 neutral. A solution with a pH greater than 7.0 is basic.
  • to calculate the molarity of a solution, divide the number of moles of the solute by the volume of the solution in litersMolarity (M) = moles of solute / liters of solution
weak base
  • a base that dissociates completely into metal ions and hydroxide ions in an aqueous solution
  • a solution in which [H +] is greater than [OH -][H +] is greater than 1*10 ^-7 M
  • an acid ionises only slightly in aqueous solution
  • a base that reacts with water for form the conjugate acid of the base and hydroxide ions
What factors affect the solubility of a substance?
  • Chemists use two ways to express the ratio of solute particles to solvent particles: in molality and in mole fractions
  • diluting a solution reduces the number of moles of solute per unit volume, but the total number of moles of solute in the solution does not change
  • agitation, temperature, particle size of teh solute
  • temperature affects the solubility of solid, liquid, and gaseous solutes in a solvent; both temperature and pressure affect the solubility of gaseous solutes
acid dissociation constant (K(sub)a)
  • a solution in which [H +] is greater than [OH -][H +] is greater than 1*10 ^-7 M
  • the ratio of the concentration of the dissociated form of an acid to the concentration of the undissociated form
  • A solution with a pH less than 7.0 is acidic. A solution with a pH of 7.0 neutral. A solution with a pH greater than 7.0 is basic.
  • a measure of the amount of solute that is dissolved in a given quantity of solvent
To 225 mL of a 0.80M solution of KI, a student adds enough water to make 1.0 L of a more dilute KI solution. What is the molarity of the new solution?
  • temperature affects the solubility of a solid solutes in a solvent; both temperature and pressure affect the solubility of gaseous solutes in a solvent. This means that temperature and pressure affect how much of a solute will dissolve in a solvent.
  • %(v/v) = (volume of solute)/(volume of solution) * 100%%(v/v) = 85 mL ethanol/250 mL * 100%%(v/v) = 85 ethanol/250 * 100%34% ethanol (v/v)
  • 0.18M
  • 0.060 mol KI / 1.000 kg H2O166.0 g KI / 1 mol KI0.5000 kg H20 0.060 mol KI / 1.000 kg H2O 166.0 g KI / 1 mol KI0.5000 0.060 / 1.000 166.0 / 1 mol KI = 5.0 g KI
How many grams of glucose are needed to make 2000 g of a 2.8% glucose (m/m) solution?
  • K(sub)a = [H +][A -]/[HA][HA] is the equilibrium concentrations of the acid[A -] is the anion from the dissociation of the acid[H +] is the hydrogen ion
  • M1V1=M2V2V1 = M2*V2/M1V1 = (0.400M * 100.0 mL)/2.00MV1 = (0.400 * 100.0 mL)/2.00V1 = 20.0 mL
  • 2.8% = (2.8 g glucose)/(100 g solution)2000 g solution * (2.8 g glucose)/(100 g solution)2000 * (2.8 g glucose)/(100)56 g glucose
  • A solution with a pH less than 7.0 is acidic. A solution with a pH of 7.0 neutral. A solution with a pH greater than 7.0 is basic.
True or false: the greater the K(sub)a value the stronger the acid.
  • True
  • False
basic solution
  • a solution that contains the maximum amount of solute for a given quantity of solvent at a constant temperature and pressure
  • a solution in which [H +] is one less than [OH -][H +] is less than 1*10 ^-7 M
  • a solution that contains a relatively small amount of solute
  • A solution with a pH less than 7.0 is acidic. A solution with a pH of 7.0 neutral. A solution with a pH greater than 7.0 is basic.
Arrhenius' list of six common acids
  • hydrochloric acid (HCl), nitric acid (HNO3), sulfuric acid (H2SO4), phosphoric acid (H3 PO4), ethanoic acid (CH3COOH), carbonic acid (H2CO3)
  • the product of the concentrations of the hydrogen ions and hydroxide ionsK(sub)w = [H +] [OH -] = 1.0 10 ^-14
  • the ratio of the concentration fo the conjugate acid times the concentration of the hydroxide ion to the concentration of the base
  • the increase of kinetic energy causes the particles of the solvent to collide with the particles of the solute, this causes the solute to break apart and dissolve faster
How does temperature affect dissolving?
  • percent by volume of a solution is the ratio of the volume of solute to the volume of solution, whereas percent by mass is the ratio of the mass of the solute to the mass of the solution
  • The magnitudes of the freezing point depression and the boiling point elevation of a solution are directly proportional to the molal concentration (m), assuming the solute is molecular, not ionic.
  • the increase of kinetic energy causes the particles of the solvent to collide with the particles of the solute, this causes the solute to break apart and dissolve faster
  • for aqueous solutions, the product of the hydrogen-ion concentratoin and the hydroxide-ion concentration equals 1.0 x 10 ^-14
miscible
  • liquids that are insoluble in one another
  • the ratio of the moles of the solute to the total number of moles of solvent and solute
  • the number of moles of solute dissolved in one liter of solution; molar concentration
  • when two liquids dissolve in each other in all proportions; the liquid that is present in the larger amount is considered the solvent
What factors affect how fast a substance dissolves?
  • agitation, temperature, particle size of teh solute
  • grams of solute per 100 grams of solvent
  • molarity, percent by volume, percent by mass
  • Either acid-base indicators of pH meters can be used to measure pH.
What are two methods that are used to measure pH?
  • Acids and bases are classified as strong or weak based on the degree to which they ionise in water.
  • Either acid-base indicators of pH meters can be used to measure pH.
  • ∆T(sub)b = K(sub)b m = 0.512˚C/m 3.00m = 1.54˚CT(sub)b = 100˚C + 1.54˚C
  • agitation, temperature, particle size of teh solute
What are three colligative properties of solutions?
  • vapour-pressure lowering, freezing-point depression, and boiling point elevation
  • for aqueous solutions, the product of the hydrogen-ion concentratoin and the hydroxide-ion concentration equals 1.0 x 10 ^-14
  • ∆T(sub)b = K(sub)b m = 0.512˚C/m 3.00m = 1.54˚CT(sub)b = 100˚C + 1.54˚C
  • molarity, percent by volume, percent by mass
How are [H+] and [OH-] related in an aqueous solution?
  • A solution with a pH less than 7.0 is acidic. A solution with a pH of 7.0 neutral. A solution with a pH greater than 7.0 is basic.
  • for aqueous solutions, the product of the hydrogen-ion concentratoin and the hydroxide-ion concentration equals 1.0 x 10 ^-14
  • The magnitudes of the freezing point depression and the boiling point elevation of a solution are directly proportional to the molal concentration (m), assuming the solute is molecular, not ionic.
  • Chemists use two ways to express the ratio of solute particles to solvent particles: in molality and in mole fractions
strong base
  • a base that dissociates completely into metal ions and hydroxide ions in an aqueous solution
  • liquids that are insoluble in one another
  • the ratio of the moles of the solute to the total number of moles of solvent and solute
  • a base that reacts with water for form the conjugate acid of the base and hydroxide ions
How are freezing-point depression and boiling-point elevation related to molality?
  • The magnitudes of the freezing point depression and the boiling point elevation of a solution are directly proportional to the molal concentration (m), assuming the solute is molecular, not ionic.
  • changes in pressure have little effect on the solubility of solids in liquids. gas solubility increases as the partial pressure of the gas above the solution increases
  • a constant that is equal to the change in freezing point for a 1-molal solution of a nonvolatile molecular soluteT(sub)f = K(sub)f * m (molality)
  • the increase of kinetic energy causes the particles of the solvent to collide with the particles of the solute, this causes the solute to break apart and dissolve faster
Ethylene glycol (EG, or C2H6O2) is added to automobile cooling systems to protect against cold weather. What is the mole fraction of each component in a solution containing 1.25 mol of ethylene glycol and 4.00 mol of water?
  • K(sub)eq [H2O] = K(sub)a = [H3O +] [CH3COO][CH3COOH]
  • 0.060 mol KI / 1.000 kg H2O166.0 g KI / 1 mol KI0.5000 kg H20 0.060 mol KI / 1.000 kg H2O 166.0 g KI / 1 mol KI0.5000 0.060 / 1.000 166.0 / 1 mol KI = 5.0 g KI
  • X(sub)EG = n(sub)EG / n(sub)EG + n(sub)H2OX(sub)H20 = n(sub)H2O / n(sub)EG + n(sub)H2OX(sub)EG = 1.25 mol / 1.25 mol + 4.00 mol = 0.238X(sub)H20 = 4.00 mol / 1.25 mol + 4.00 mol = 0.762
  • K(sub)a = [H +][A -]/[HA][HA] is the equilibrium concentrations of the acid[A -] is the anion from the dissociation of the acid[H +] is the hydrogen ion
concentration of a solution
  • contains more solute than it can theoretically hold at a given temperature
  • the ratio of the moles of the solute to the total number of moles of solvent and solute
  • a solution that contains less solute that a saturated solution at a given temperature and pressure
  • a measure of the amount of solute that is dissolved in a given quantity of solvent
What effect does dilution have on the amount of solute?
  • Either acid-base indicators of pH meters can be used to measure pH.
  • diluting a solution reduces the number of moles of solute per unit volume, but the total number of moles of solute in the solution does not change
  • Chemists use two ways to express the ratio of solute particles to solvent particles: in molality and in mole fractions
  • ∆T(sub)b = K(sub)b m = 0.512˚C/m 3.00m = 1.54˚CT(sub)b = 100˚C + 1.54˚C
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Multiple Choice Questions
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