Chem 2 chapter 13

Entropy (S) is related the the ___ of movement of the particles in a system. The particles of a solid are highly ordered and therefore have ___ freedom of movement than the particles of a liquid. A liquid has ___ entropy than a solid.

freedom; less; more

Calculate the freezing point of a solution containing 0.204 mol of ibuprofen in 250. g of ethanol. (K(f) for ethanol = 1.99 degrees C*kg/mol and T(f) = -117.3degrees C)

-118.9 degrees C 0.204 ______ x 1.99 = 1.62 degrees C 0.250 T(f) = -117.3 - 1.62 = 118.9 degrees C

Calculate the osmotic pressure of a solution containing 3.55g of sucrose (C12H22O11; molar mass 342.3 g/mol) in sufficient water to give 825mL of solution at 22degrees C.

0.0126 x 0.0821 x 295= 0.305 atm

A solution of volume 150 mL contains 0.015 g of Pb2+ ions. Calculate the concentration of Pb2+ in ppm if the density of the solution is 1.02 g/mL

0.015g _____ x 10^6 = 98.0 ppm 153g

Calculate the mass of O2 that will dissolve in 2.50 L of H2O that is in contact with air at 20 degrees C, where the partial pressure of O2 is 0.209 atm. (k(H) for O2 in H2O at 20 degrees C = 1.28 x 10^3 mol/L*atm)

0.0214 g O2 1.28 x 10^3 mol ____________ x 0.209 atm = 2.68 x 10^-4 mol/L L x atm 2.68 x 10^-4 mol _____________ x 2.50 L x 32.00 g 1 L _____ 1 mol =0.0214 g O2

Describe solutions comprising of gases and/or solids

1. A gas may dissolve in a solid by occupying the spaces between the solid particles. 2. Gas-gas solutions form readily because all gasses are miscible with each other. 3. Gas- solid solutions are important as catalysts.

Describe as-liquid solutions

1. A polar gas will dissolve readily in a polar solvent. 2. A nonpolar gas will not dissolve readily in a polar solvent. 3. Gases appear to be more soluble in aqueous solutions if they react with H2O after dissolving.

What are the features of a nonvolatile, nonelectrolyte solute?

1. A solute that dissolves but produces no ions in solution. 2. A solute that has a negligible vapor pressure at the boiling point of the solvent.

Explain the effect of a nonvolatile solute on the boiling point of a solution

1. Boiling point elevation occurs because the pressure of a nonvolatile solute lowers the vapor pressure of the solvent. 2. The lower concentration of the nonvolatile solute, the higher the vapor pressure of the solution. 3. The greater the concentration of the solute, the higher the vapor pressure of the solution. 4. A solution boils at a higher temperature than the pure solvent.

Describe freezing point depression for a solution.

1. Delta T(f) is a positive value 2. The freezing point consant K(f) is characteristic of the solvent 3. Freezing point depression is proportional to the molality of the solution

Correctly describe entropy

1. Entropy is related to the number of ways a system can dispense its energy. 2. Entropy is related to the freedom of motion of the particles in a system. 3. The entropy of a gas is higher than the entropy of a liquid.

Describe the molality and molarity of a solution

1. For a dilute aqueous solution molality and molarity are nearly equal. 2. Both molarity and molality express concentration in terms of moles of solute. 3. M must be calculated using the volume of the solution, not the volume of the solvent.

Describe osmotic pressure of a solution

1. Osmotic pressure is directly proportional to the molarity of the solution 2. Osmotic pressure increases with temperature

Explain the effect of a nonvolatile solute on the vapor pressure of a solution.

1. Solute particles on the solution surface decrease the number of solvent particles that can escape. Vapor pressure is lowered. 2. The entropy of the solution is higher than that of the pure solvent. Solvent has less tendency to vaporize and vapor pressure is lowered.

Will HCl or NaCl be more soluble in the solvent Ch3OCH3? Why?

1. The dipole-dipole forces in an HCl/CH3OCH3 solution are similar in strength to the dipole-dipole forces between CH3OCH3 molecules. 2. HCl will be more soluble in CH3OCH3.

Describe the heat of solvation for a solution process

1. The heat of solvation is called the heat of hydration, if H2O is the solvent. 2. The heat of solvation in the enthalpy changes that occurs when a solute particle is surrounded by solvent particles. 3. If delta H(hydr) <0, indicates that more energy is released due to solvent-solute attractions than the energy absorbed in separating solvent particles.

Describe a solution that is in contact with undissolved solute at a given temperature

1. The rate at which solute is dissolving is equal to the rate at which solute particles are crystallizing from solution. 2.The concentration of dissolved solute will not change. 3. Undissolved solute is in equilibrium with dissolved solute.

Describe the different ways of expressing the concentration of a solution.

1. The unit for molality is mol/kg 2. To calculate mole fraction for a given mass of a reactant or product, the masses of all solution components must be known.

Describe the vapor pressure of a solution containing a volatile nonelectrolyte solute.

1. The vapor pressure of both volatile will be lowered. 2. The quantity of the volatile component in the vapor will be greater than that in the solution. 3. The vapor pressure of each volatile component can still be calculated using P(A) = X(A)P^o(A)

Describe the effect of temperature on the solubility of a solid in a given solvent

1. There is no clear correlation between deltaH(soln) and solubility at different temperature. 2. In general, solids are more soluble at higher temperatures than at lower temperatures.

Describe Henry's law for gases

1. This law shows that the solubility of a gas increases with pressure. 2. P(gas) is the partial pressure of the gas above the liquid. 3. S(gas) is the solubility of the gas at a particular temperature.

Give the correct formula to calculate the concentration of a solution in ppm and ppb mass

1. ppm = mall of solute __________ x 10^6 mass of solution 2. ppb = mass of solute __________ x 10^ 9 mass of solution

Certain substances such as alcohols are able to dissolve fairly readily in both polar and nonpolar solvents. Explain this behavior.

1.Alcohols form strong interaction with both types of solvent. 2.The Hydrocarbon portion of the alcohol interacts with the nonpolar solvent through dispersion forces. 3.Alcohols have dual polarity since they possess a polar OH group as well as a nonpolar hydrocarbon portion.

Correctly describe the enthalpy changes associated with the formation of a solution.

1.Energy is released when the solvent and solute particles attract each other and mix to form a solution. 2.The overall enthalpy change for the solution depends on the balance of energy absorbed vs. energy released. 3. Energy is absorbed to separate the solvent particles from each other.

Calculate the expected boiling point of a solute containing 0.72mol of MgCl2 in 1.00 kg of H2O, if K(b)=0.512degrees C*kg/mol

100.0 degrees C +(2.16 x 0.512)= 101.1 degrees C

A solution contains 25.0 g ethanol (C2H5OH; molar mass 46.07g/mol) in 500.g H2)(molar mass 18.02g/mol) at 23 degrees C. If the vapor pressure of pure H2Oat this temperature is 20.57 torr, What is the vapor pressure of the solution?

20.1torr 1.0.019x20.57= .390torr (20.57-0.390)=20.1(final answer)

O2 in aqueous solution

Dipole-induced dipole

I2 in hexane

Dispersion forces

CH3OH in H2O

Hydrogen Bonding

How does the presence of a strong electrolyte in solution effect the colligative properties of a solution when compared to the same number of moles of a nonelectrolyte solute?

The electrolyte dissociates or ionizes to give a larger number of moles of dissolved particles with a greater effect on the colligative properties.

Dipole-induced dipole forces

a nonpolar solute in a polar solvent

Ion-induced dipole forces

a nonpolar solute in a polar solvent that also contains dissolved ions

A protein is a macromolecular polymer consisting of ___ acids covalently bonded of the side chains of these components determine the intermolecular forces between different parts of the same protein molecule, thus influencing the overall ___ and function of a particular protein.

amino; shape

Ion-dipole forces

an ionic solute in a polar solvent

Gramicidin A and similar ___ function by forming a channel through the cell membrane. The ___ groups along the outside of the channel interact with the membrane interior through ___ forces, while the inside of the channel is lined wit polar groups, which allow K+ and Na+ ions to pass through the cell via ion- dipole interactions.

antibiotics; nonpolar; dispersion

Light passes straight through a solution without scattering. By contrast light passed through a(n) ___will scatter because the dispersed particles are similar in size to the wavelength of visible light. The phenomenon is known as the ___ effect and is an important tool in distinguishing between the different types of mixtures.

colloid; Tyndall

A saturated solution of a gas in a liquid (in a closed system) is at equilibrium with a fixed number of gas molecules leaving and entering the solution every second. If the pressure on the system is increased, the gas volume will ___, thus disturbing the system. This causes ___ gas molecules to dissolve in order to reestablish equilibrium. A gas is therefore ___ soluble at higher pressures.

decrease; more; more

The magnitude of the heat of hydration of an ion ___ down a group on the periodic table and ___ from left to right across a period. (The term magnitude indicates the value of the heat of hydration, not its sign.)

decreases; increases

Molarity to Molality

density of the solution

When an ionic solute dissolves in water, the ions ___ and each ion becomes surrounded by a cluster of H2O molecules called a(n) ___ shell.

dissociate; hydration

nonelectrolyte

does not dissociate at all in aqueous solution; no ions are produced and the solution does not conduct an electric current.

Both ___and entropy changes determine whether or not a given solvent-solute pair will form a solution. A solution process for which deltaH(soln) > 0 will still be spontaneous if it is counter-balanced by a corresponding ___ in the entropy of the system.

enthalpy; increase

If more solute is added to a solvent, more than is able to dissolve at a given temperature, a(n) ___ will be established between dissolved and undissolved solute. The rate at which solute continues to dissolve is ___ to/than the rate at which solute crystallizes from solution.

equilibrium; equal

A solution forms when the attractive ___ between the solute and solvent are ___ in strength to the solvent-solvent and solute-solute attractions and are therefore able to replace them.

forces; similar

A solution containing 1 mol of a strong electrolyte will have a(n) ___ effect on the colligative properties of the solution than 1 mol of a nonelectrolyte. A strong electrolyte will dissolve or ionize in aqueous solution and therefore the total number of dissolved solute particles is ___ for 1 mol of a strong electrolyte than for 1 mol of a nonelectrolyte solute.

greater; greater

A solution that has a ___entropy than either the pure solvent or pure solute because in the solution there are a ___number of interactions between particles and therefore ___ ways to distribute the energy of the system.

higher; greater; more

A solution containing a nonvolatile solute always boils at a ___ temperature than the pure solvent. The vapor pressure of the solution is ___ than the vapor pressure of the pure solvent; hence the solution must be heated to a ___ temperature in order for the vapor pressure to equal the external pressure.

higher; lower; higher

The charge density of an ion has a significant effect on its heat of hydration. The ___ the charge on an ion and the ___ the size, the greater its attraction to the H2O molecules surrounding it and the more ___ the value of delta H(hydr of the ion)

higher; smaller; negative

Substances that have similar___forces are able to dissolve in each other, giving rise to the phrase "like ___ like."

intermolecular; dissolves

NaCl in CH3CH2OH

ion dipole

A colloid consists of small particles dispersed in a dispersion medium. The small particles size results in a very ___ total surface area; hence colloid particles interact strongly with each other through various ___ forces.

large; intermolecular

A solute that is nonvolatile is one that has a relatively ___ vapor pressure at the boiling point of the solvent.

low

weak electrolyte

low % dissociation in aqueous solution; a few ions are produced and the solution conducts poorly

parts by mass

mass of solute __________ mass of solution

Solubility is defined as the ___ amount of solute that is able to dissolve in a fixed amount of a particular solvent at a particular___ and pressure.

maximum; temperature

mole fraction (X)

mol of solute _________ total # of moles present

Molarity (M)

mol of solute __________ L of solution

Molality (m)

mol of solute __________ kg of solvent

Mole fraction to molality

molar mass

Mass percent to molality

molar mass and density of the solution

X(solvent)

mole fraction of the solvent in the solution

Most solids ar ___ soluble in a particular solvent at higher emperatures than at lower temperatures, although there are some exceptions. The solubility of a gas in water will generally ___ as temperatures increase.

more; decrease

Colligative properties are properties of a solution that depend only on the ___ of solute particles on a given volume of solution, not on their ___.

number; type

Proteins that are soluble in water have ___ exertions and ___ interiors.

polar ionic; nonpolar

The self- assembly of phospholipids into a lipid bllayer is energetically favorable due to the ion-dipole forces that occur between the ___ heads and water at the surface of the bllayer, and the ___ forces that occur between the nonpolar talls.

polar; dispersion

Dispersion forces

present in all solutions; principal intermolecular force when both solvent and solute are nonpolar

A solution that contains the maximum amount of dissolved solute in a fixed quantity of solvent at a particular temperature is called a(n)___ solution. This type of solution will have some ___ solute present, which will be in equilibrium with the dissolved solute.

saturated; undissolved

strong electrolyte

shows 100% dissociation in aqueous solution; ions are produced and the solution conducts electricity well

The most abundant component of a solution is usually called the ___, whereas the other dissolved components are called___.

solvent; solute

P^o(solvent)

vapor pressure of the pure solvent

P(solvent)

vapor pressure of the solvent in the solution