Exam 2 Activity of Water Flashcards

1
Q

Keq formula

A

Keq = ([C][D]) / ([A][B])

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2
Q

pH formula

A

pH = -log[H+]

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3
Q

Freezing point depression formula

A

deltaTf = Kf*m

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4
Q

Universal gas law

A

PV = nRT

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5
Q

T or F: The formula expression are applicable only where ideal behavior is implied i.e. intermolecular, interatomic and/or interionic forces may not be ignored

A

False; they can be ignored

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6
Q

T or F: Interionic attractive forces between oppositely charged ions of strong electrolytes in solution interfere with movement of these ions

A

True

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7
Q

T or F: A strong electrolyte may be completely ionized in solution, yet it is incompletely dissociated into free ions

A

True

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8
Q

T or F: There is interference in the freedom of each of the ions to act towards influencing the freezing point of the solution

A

True

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9
Q

The ______ of the different ions in solution with each other (or even molecules of the same substance as in the case of solutions of nonelectrolytes) results in a _____ between the experimental value of a certain physical or chemical property and the value calculate using stoichiometric concentration in the mathematical expression

A

Interference; deviation

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10
Q

It is better to think of the solution as having an effective concentration that is called ______

A

Activity

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11
Q

Activity, in general, is ___ (more/less) than the actual or stoichiometric concentration of the solute

A

Less

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12
Q

Chemical or physical property =

A

f (activity)

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13
Q

An electrode of a pH meter during a pH measurement responds to the _____ of H+, not its concentration

A

activity

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14
Q

T or F: Since an electrode of a pH meter during a pH measurement responds to the activity of H+, therefore pH = -log(activity H+)

A

True

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15
Q

Ideal gas law looks at ____ vs. pressure

A

Fugacity

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16
Q

Activity measures the _____ ______ of a chemical species whether in the state of gas, liquid, or solid, or whether present as a single species or in combination with other species

A

Net effectiveness

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17
Q

T or F: Activity may be viewed as corrected concentration

A

True

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18
Q

T or F: Activity takes into account the stoichiometric concentration (or pressure in case of gases) as well as any intramolecular attractions, repulsions, or interactions between solute and solvent in solution, association, and ionization

A

False; …. as well as any intermolecular (not intramolecular)

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19
Q

T or F: The activities normally used are relative activites

A

True

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20
Q

T or F: It is possible to assign an absolute value to the activity of a component in solution. Therefore, in order to make quantitative comparisons, a standard state is chosen

A

True

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21
Q

The ____ state of a component in a solution is the state of the component at unit activity

A

standard state

22
Q

The ____ activity of a component is the _____ of activity in an observed state relative to its value in the standard state

A

relative activity; ratio of activity

23
Q

T or F: Activity is dimensionless

24
Q

Standard state of a solvent is the pure liquid at ___ atmosphere and at a definite temperature. Therefore, for the pure liquid, a = ___

25
T or F: If the liquid solute isn't miscible with the solvent, the standard state is the pure solute
False; if the liquid solute is miscible with the solvent
26
T or F: If a solute has a limited solubility, the standard state is a hypothetical solution of unit concentration under conditions of ideal behavior (the solution has characteristics of an infinitely dilute solution)
True
27
Activity is a measure of the _____ tendency of a component in the system, which vapor pressure is a component of
Escaping tendency
28
T or F: Escaping tendency (vapor pressure) is much lower in alcohol vs. water
False; escaping tendency is much lower in water
29
The separation of one component of a solution from another component by means of pressure exerted on a semipermeable membrane
Reverse osmosis
30
Most units of reverse osmosis use a _____ _____ membrane which preferentially permits water to pass through over ions and dissolved matter
cellulose acetate
31
The pores in RO membranes are 5-20 Angstrom units in diameter, which is __-__ cm, and therefore molecules larger than the pores (i.e. with a molecular weight greater than ___) are separated by a simple sieve process
5x10^-8 to 2.5x10^-7 | MW > 200
32
Rejection of salts is as high as ___%, while rejection of most organics is ___%, thus water of extremely high quality can be produced
98%; 100%
33
T or F: In osmosis, water will flow because of potential energy differences from the less concentrated to the more concentrated solution until the system is in equilibrium
True
34
T or F: The addition of pressure to the concentrated solution will stop the transport of water across the membrane when the applied pressure equals the apparent osmotic pressure between the two solutions
True
35
T or F: Apparent osmotic pressure is the difference in the absolute osmotic pressure of each solution. Such a difference is a measurement of the potential energy difference between the two solutions
True
36
T or F: The absolute osmotic pressure is the potential energy difference between any solution and water
True
37
T or F: As more pressure is released from the more concentrated side, the water begins to flow from the more concentrated side to the less concentrated side
False; as more pressure is applied to the more concentrated side
38
At a _____ (static/infinite) dilution, the solute species are separated from each other so far that they do not interact
Infinite
39
The solution behaves ___ and under these conditions, activity = _____
ideally; activity = concentration
40
T or F: As the concentration of the solution is increased, the activity/concentration ratio is increased
False: the ratio is decreased
41
Formula for effective concentration or activity
a = y*m
42
In the formula a = y*m, y is a correction factor called the
Activity coefficient
43
The activity coefficient (y) = 1 in ____ solutions, and therefore, activity = concentration
ideal solutions
44
Which correction coefficient (y) is used for strong electrolytes, and what is the formula?
Strong electrolytes use the correction coefficient of mean ionic activity where (y+/-) = (y+ y-)^0.5
45
Which correction coefficient is used for ions?
Ionic activity coefficient (yi)
46
The mean ionic activity coefficients of all electrolytes is 1 at ___ dilution
Infinite dilution
47
T or F: Mean ionic activity coefficients are expected to equal one at infinite dilution because the solution behaves ideally and (y+/-) is equal to one in the case of ideal solutions
True
48
Log formula for yi
Look up in notes
49
Log formula for y+/-
Look up in notes
50
____ strength is the measure of the intensity of the electrostatic field in a solution due to the presence of ions, and provides a basis for evaluating electrostatic interactions between ions
Ionic strength
51
T or F: Salts that do not have a common ion with a slightly soluble salt can influence its solubility
True
52
What are four areas that ionic strength are important in?
Rates of ionic reactions Solubility of sparingly soluble salts Effects of salts on pH of buffers Biological research