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indiabix > DAY 1 > Flashcards

DAY 1 Flashcards

1
Q

demonstrated the relationship of water and cholera

A

Dr. John Snow

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2
Q

show the relationship of typhoid and water contamination

A

Dr. William Budd

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3
Q

half life is defined as

A

ln(0.5)k^-1 or 0.693K-1

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4
Q

Commercial sulfuric acid (H2SO4) is often purchased as a 93 wt% (weight percent) solution. Find
the concentration of this solution of H2SO4 in units of milligram per liter, molarity, and normality. Sulfuric acid (100%) has a specific gravity of 1.839. Assume that the temperature of the
solution is 15◦C.

A

36.30 Eq / L or 36.3 N

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5
Q

Determine the equivalent weight of each of the following: Ca2+, CO2−
3 , CaCO3

A

50.05 g · g / Eq or 50.05 mg /mEq

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5
Q

Find the mass of sodium bicarbonate (NaHCO3) that must be added a 1.00 L volumetric flask
containing distilled water to make a 1.0 M solution. Find the normality of the solution.

A

84 g / L

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6
Q

The pH of a water is measured to be 7.5. The concentration of bicarbonate was measured to be
1.3 × 10−3 M. What are the concentrations of carbonate, carbonic acid, and CT? Assume this system is closed to the atmosphere.

A

1.384 × 10−3 M ≈ 1.4 × 10−3 M

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7
Q

The pH of a water is measured to be 7.5. What are the concentrations of carbonate, bicarbonate,
carbonic acid, and CT? Assume this system is open to the atmosphere. The temperature is 25◦
C.
The Henry’s constant for carbon dioxide is 10−1.47 M · atm−1 at this temperature. The partial
pressure of carbon dioxide is 10−3.53 atm.

A

1.70 × 10−4 M ≈ 1.7 × 10−4 M

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8
Q

This ability to resist change is referred to as

A

buffering capacity

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9
Q

describe a water’s ability to resist changes in pH on the
addition of acid, therefore, it is also called acid-neutralizing capacity

A

alkalinity

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10
Q

is defined as the sum of all titratable bases to a pH of approximately 4.5.

A

Alkalinity

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11
Q

A water contains 100.0 mg · L−1 CO2−
3 and 75.0 mg · L−1 HCO−
3 at a pH of 10 (T = 25◦
C).
Calculate the exact alkalinity. Approximate the alkalinity by ignoring the appropriate chemical
species.

A

233 mg · L−1 as CaCO3

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12
Q

ability of a water to resist changes in pH due to the addition of base. Therefore, it is also called
base-neutralizing capacity.

A

Acidity

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13
Q

essentially, the extent to which a unit mass of soil can exchange a mass of
a certain ion of interest

A

Exchange capacity

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14
Q

is essentially the attachment of a chemical to either the mineral or organic portions of soil particles and includes both
adsorption and absorption

A

Sorption

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15
Q

A soil sample is collected and the soil water is analyzed for the chemical compound 1,2-dichloroethane (DCA). The concentration in the water is found to be 12.5 g · L−1. The organic matter content of the soil is 1.0%. Determine the concentration of DCA that would be sorbed to the soil and that associated with the organic matter. DCA has a Kd of
0.724 (ug · kg−1
)(ug · L−1)−1 .

A

= 905 ug · kg−1

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16
Q

A 1-m3 sample of air was found to contain 80 g · m−3 of SO2. The temperature and pressure
were 25.0◦
C and 103.193 kPa when the air sample was taken. What was the SO2 concentration in
parts per million?

A

0.030 ppm of SO2

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17
Q

A solution of sodium bicarbonate is prepared by adding 45.00 g of sodium bicarbonate to a 1.00-L volumetric flask and adding distilled water until it reaches the 1.00-L mark. What is the concentration of
sodium bicarbonate in units of (a) milligrams per liter, (b) molarity, (c) normality and (d) milligrams per
liter as CaCO3?

A

(a) 4.5 × 104 mg · L−1 (b) 0.536 M (c) 0.536 N (d) 2.68 × 104 mg · L−1 as CaCO3

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18
Q

A magnesium hydroxide solution is prepared by adding 10.00 g of magnesium hydroxide to a volumetric
flask and bringing the final volume to 1.00 L by adding water buffered at a pH of 7.0. What is the concentration of magnesium in this solution? (Assume that the temperature is 25◦
C and the ionic strength is
negligible).

A

0.17 M

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19
Q

A ferric phosphate solution is prepared by adding 2.4 g of ferric phosphate to a volumetric flask and
bringing the final volume to 1.00 L by adding water having a phosphate concentration of 1.0 mg · L−1 .
What is the concentration of soluble iron in this solution? (Assume that the temperature of the solution is
25◦
C.)

A

1.20 × 10−17 M

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19
Q

A solution has an H+ concentration of 10−5 M. (a) What is the pH of this solution? (b) What is the pOH?
(Assume that the temperature of the solution is 25◦
C.)

A

(a) 5 (b) 9

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20
Q

A solution of acetic acid is prepared in water by adding 11.1 g of sodium acetate to a volumetric flask and
bringing the volume to 1.0 L with water. The final pH is measured to be 5.25. What are the concentrations
of acetate and acetic acid in solution? (Assume that the temperature of the solution is 25◦
C.)

A

[HA] = 0.033 M [A−] = 0.102 M

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20
Q

The concentration of a chemical degrades in water according to first-order kinetics. The degradation
constant is 0.2 day−1
. If the initial concentration is 100.0 mg · L−1, how many days are required for the concentration to reach 0.14 mg · L−1?

A

32.9 days

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21
Q

Hypochlorous acid decays in the presence of ultraviolet radiation. Assume that degradation occurs according to first-order kinetics and the rate of degradation was measured to be 0.12 day−1 (at a particular sunlight
intensity and temperature). Given this, how long does it take for the concentration of hypochlorous acid to
reach nondetectable levels (0.05 mg · L−1 ) if the initial concentration were 3.65 mg · L−1 ?

A

35.8 days

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22
Q

Show that a 4.50% by weight mixture contains 45.0 kg of substance in a cubic meter of water (i.e., 4.50% =
45.0 kg · m−3 ).

A

45 kg · m−3

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23
Q

A water initially contains 40 mg · L−1 of Mg2+. The pH of the water is increased until the concentration of
hydroxide ion (OH−) is 0.001000 M. What is the concentration of magnesium ion in this water at this pH? Give your answer in milligrams per liter. Assume that the temperature of the solution is 25◦C.

A

0.4423 mg · L−1

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24
Q

You made up a saturated solution of calcium sulfate (CaSO4). The temperature is 25°C. You then add
5.00 × 10−3 M sodium sulfate (Na2SO4 ). What are the concentrations of calcium and sulfate after equilibrium is reached? The pKs of CaSO4 is 4.58.

A

Ca2+ = 0.0032 M, SO2−
4 = 0.0082 M

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25
Q

The pH of a finished water from a water treatment process is 10.74. What amount of 0.02000 N sulfuric
acid, in milliliters, is required to neutralize 1.000 L of the finished water, assuming that the alkalinity
(buffering capacity) of the water is zero?
How many milliliters of 0.02000 N hydrochloric acid would be required to perform the neutralization

A

: 27.5 mL

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26
Q

What is the pH of a water that, at 25◦
C, contains 0.5000 mg · L−1 of hypochlorous acid? Assume equilibrium has been achieved. Ignore the dissociation of water. Although it may not be justified based on the data
available to you, report the answer to two decimal places.

A

pH 6.28

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27
Q

What is the “exact” alkalinity of a water that contains 0.6580 mg · L−1 of bicarbonate, as the ion, at a pH
of 5.66?

A

0.4302 mg · L−1 as CaCO3

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28
Q

What is the pH of a water that contains 120.00 mg · L−1 of bicarbonate ion and 15.00 mg · L−1 of carbonate ion?

A

9.43

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29
Q

Determine the density of nitrogen gas at a pressure of 122.8 kPa and a temperature of 298.0 K

A

1.39 kg · m−3

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30
Q

What volume would one mole of an ideal gas occupy at 25.0◦
C and 101.325 kPa?

A

24.46 L

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31
Q

A 1-m3 volume tank contains a gas mixture of 18.32 mol of oxygen, 16.40 mol of nitrogen, and 6.15 mol of
carbon dioxide. What is the partial pressure of each component in the gas mixture at 25.0◦
C?

A

O2: 45.4 kPa, N2: 40.6 kPa, CO2: 15.2 kPa

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32
Q

A 28-L volume of gas at 300.0 K contains 11 g of methane, 1.5 g of nitrogen, and 16 g of carbon dioxide.
Determine the partial pressure exerted by each gas.

A

CH4: 61.2 kPa, N2: 4.77 kPa, CO2: 32.4 kPa

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33
Q

The partial pressures of the gases in a 22,414-L volume of air at STP are: oxygen, 21.224 kPa; nitrogen,
79.119 kPa; argon, 0.946 kPa; and carbon dioxide, 0.036 kPa. Determine the gram-molecular weight
of air.

A

28.966

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34
Q

Convert the concentration of NO2 from 0.55 ppm to units of micrograms per cubic meter, given that the gas
has a temperature of 290 K and pressure of 100.0 kPa.

A

1048.8, or 1050 ug · m−3

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34
Q

A chemical, SpartanGreen, has a partition coefficient of 12,500 (mg · kg−1 )(mg · L−1 )
−1. If the concentration of this chemical in water is found to be 105 g · L−1, at equilibrium, what is the concentration on
the soil?

A

1312.5 mg · kg−1

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35
Q

contain two or three monosaccharides linked by covalent bonds called
glycosidic linkages.

A

Oligosaccharides

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35
Q

can contain polymeric chains of several hundred to several thousand
monosaccharides

A

Polysaccharides

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36
Q

those with five carbons

A

pentoses

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37
Q

A sugar with three carbons

A

triose

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38
Q

those with six carbons

A

hexoses

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39
Q

Cytosine, thymine, and uracil
are

A

pyrimidines

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40
Q

Adenine and guanine

A

purines

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40
Q

lack a nucleus, the region inside a cell containing the DNA

A

Prokaryotic cells

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40
Q

diverse group of compounds, make up more than 50% of the dry weight of cells.

A

Proteins

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41
Q

are lipids with a carbon skeleton containing four fused hydrocarbon rings

A

Steroids

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42
Q

An increase or decrease in the material (e.g., mass or moles) in the
system.

A

Accumulation

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42
Q

A process in which material is neither added to nor removed from
the process during its operation.

A

Batch process

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43
Q

A system that does not have material crossing the system boundary.

A

Closed system

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44
Q

A material balance on a single chemical component in a system.

A

Component balance

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45
Q

Matter is neither created nor destroyed overall

A

Conservation of mass

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46
Q

The depletion of a component in a system due to chemical reaction.

A

Consumption

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47
Q

A process in which material enters and/or exits continuously.

A

Continuous process

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48
Q

The amount of material (e.g., mass or moles) in the process at the
end of the processing interval.

A

Final condition

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49
Q

An open system with material entering and/or leaving.

A

Flow system

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50
Q

The appearance of a component in a system because of chemical reaction.

A

Generation

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51
Q

The amount of a material (e.g., mass or moles) in the process at
the beginning of the processing interval.

A

Initial condition

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52
Q

A depletion of material (usually mass or moles) in the
system.

A

Negative accumulation

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53
Q

A process in which material enters the system but product is
not removed during operation.

A

Semi-batch process

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54
Q

A system for which all the conditions (e.g., temperature,
pressure, amount of material) remain constant with time

A

Steady-state system

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55
Q

Any arbitrary portion of or whole process that is considered for analysis.

A

System

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56
Q

A system for which one or more of the conditions (e.g., temperature, pressure, amount of material) of the system vary with time. Also known
as an unsteady-state system.

A

Transient system

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57
Q

A system for which one or more of the conditions (e.g., temperature, pressure, amount of material) of the system vary with time. Also known as a transient system.

A

Unsteady-state system

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58
Q

The number of variables whose values are unknown minus the number of independent equations

A

Degrees of freedom

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59
Q

A set of equations that are not independent

A

Dependent equations

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60
Q

A problem in which the number of degrees of freedom is zero.

A

Exactly specified

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60
Q

An equation based on information not explicitly provided in a problem such as the sum of the mass fractions is one.

A

Implicit equation

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61
Q

A set of equations for which the rank of the coefficient matrix formed from the equations is the same as the number of equations.

A

Independent equations

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62
Q

A set of equations (or a problem) that is comprised of more equations than unknowns.

A

Over specified

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63
Q

discovered radioactivity in 1896

A

Henri Becquerel

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64
Q

helium nuclei

A

alpha particles

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65
Q

electrons.

A

beta particles

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66
Q

high-energy photons

A

gamma rays

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67
Q

positively charged electrons

A

positrons

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68
Q

the new element has the same mass number but an atomic number one unit smaller

A

positrons

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68
Q

no transmutation takes place; only the energy of the nucleus is lowered

A

gamma rays

69
Q

The new
element has the same mass number but an atomic
number one unit greater.

A

beta particles

70
Q

the new element has an atomic number two units
lower and a mass number four units smaller

A

alpha particle

71
Q

the new element has the
same mass number but an atomic number one unit
smaller.

A

electron capture

71
Q

The time required for half of the sample to decay

A

half-life

72
Q

Radiation is detected and counted by devices such as

A

Geiger-Müller counters

73
Q

curie (Ci)

A

3.7 10^10 disintegrations per second.

73
Q

the absorbed dose is measured

A

rads

74
Q

measure of relative damage caused by type of radiation.

A

rem

75
Q

is the combining (fusing) of two
lighter nuclei to form a heavier nucleus

A

Nuclear fusion

75
Q

If 10.0 mg of is administered to a patient, how much is left in the body
after 32 days?

A

0.625 mg

76
Q

A radioactive isotope with an intensity (activity) of 100 mCi per vial is
delivered to a hospital. The vial contains 10 mL of liquid. The instruction
is to administer 2.5 mCi intravenously. How many milliliters of the liquid
should be administered?

A

0.25mL

77
Q

If the intensity of radiation is 28 mCi at a distance of 1.0 m, what is the intensity at a distance of 2.0 m?

A

7.0 mCi

78
Q

Suppose 50.0 mg of potassium-45, a beta emitter, was isolated in pure form. After one hour, only 3.1 mg of the radioactive material was left. What is the half-life of potassium-45?

A

4 half-lives in 60 min 60 min/4 15 min

79
Q

Assuming the same amount of effective radiation, in rads, from three sources, which would be the most damaging to the tissues: alpha particles, beta parti-
cles, or gamma rays?

A

Alpha particles are the most damaging to tissue

79
Q

In 1986, the nuclear reactor in Chernobyl had an accident and spewed radioactive nuclei that were carried by the winds for hundreds of miles. Today, among the child survivors of the event, the most common damage is thyroid cancer. Which radioactive nucleus do you expect to be responsible for these cancers?

A

Iodine-131, which is concentrated in the thyroid,
where the radiation can induce thyroid cancer.

80
Q

is used for cancer therapy

A

Cobalt-60

81
Q

used in heart scans and exercise
stress tests.

A

Thallium-201

82
Q

used to measure the water content of the body

A

Tritium

82
Q

used for kidney scans.

A

Mercury-197

83
Q

We have 27.5 g of sodium fluoride, NaF, the form of fluoride ions most commonly used in fluoride toothpastes. How many moles is this?

A

0.655 mol NaF

84
Q

A principle
stating that when a stress is
applied to a system in chemical
equilibrium, the position of the
equilibrium shifts in the direction
that will relieve the applied stress

A

Le Chatelier’s principle

85
Q

An acid that can give up only one proton

A

Monoprotic acid

86
Q

An acid that can
give up two protons

A

Diprotic acid

86
Q

Ka for hydrocyanic acid, HCN, is 4.9 10210 . What is its pKa?

A

pKa is 9.31

87
Q

Ka for benzoic acid is 6.5 1025. What is the pKa of this acid?

A

4.19.

87
Q

The [OH2] of an aqueous solution is 1.0 10212 M. What is its [H3O]?

A

1.0x10^22

88
Q

Which is the stronger acid:
(a) Carbonic acid, pKa 6.37, or ascorbic acid (vitamin C), pKa 4.1?
(b) Aspirin, pKa 3.49, or acetic acid, pKa 4.75?

A

(a) ascorbic acid (b) aspirin

88
Q

The [H3O1] of an acidic solution is 3.5 1023 M. What is its pH?

A

2.46

89
Q

The pH of tomato juice is 4.1. What is its [H3O1]? Is this solution
acidic, basic, or neutral?

A

7.8 1025, acidic

89
Q

The [OH2] of a solution is 1.0 1024 M. What are the pOH and pH of this
solution?

A

pOH 4, pH 10

90
Q

Calculate the concentration of an acetic acid solution using the following
data. Three 25.0-mL samples of acetic acid were titrated to a phenolphthalein end point with 0.121 M NaOH. The volumes of NaOH were
19.96 mL, 19.73 mL, and 19.79 mL.

A

0.0960 M

91
Q

What is the pH of a hydrocyanic acid buffer solution containing 0.25 mol/L
of hydrocyanic acid, HCN, and 0.50 mol/L of cyanide ion, CN2? See Table 9.3
for the pKa of hydrocyanic acid.

A

9.61

92
Q

Board of Chemical Engineering who gave the licensure examination

A

Engr. Ofelia V. Bulaong

93
Q

The label on a bottle of vinegar says it contains 5.0% acetic acid,
CH3COOH. The bottle contains 240 mL of vinegar. How many grams of
acetic acid are in the bottle?

A

12 g CH3COOH

94
Q

If 6.0 g of NaCl is dissolved in enough water to make 300 mL of solution,
what is the w/v percent of NaCl?

A

2.0% w/v

94
Q

The label on a bottle of vinegar says it contains 5.0% acetic acid,
CH3COOH. The bottle contains 240 mL of vinegar. How many grams of
acetic acid are in the bottle?

A

12 g CH3COOH

95
Q

We dissolve 18.0 g of Li2O (molar mass 29.9 g/mol) in sufficient water to
make 500 mL of solution. Calculate the molarity of the solution.

A

0.722 M

96
Q

The concentration of sodium chloride in blood serum is approximately
0.14 M. What volume of blood serum contains 2.0 g of NaCl?

A

0.24 L 240 mL

97
Q

Suppose we have a bottle of concentrated acetic acid (6.0 M). How would
we prepare 200 mL of a 3.5 M solution of acetic acid?

A

0.12 L

98
Q

A system, such as fat in milk, consisting of a liquid with
or without an emulsifying agent
in an immiscible liquid, usually
as droplets of larger than colloidal

A

Emulsion

98
Q

A property of a solution that depends only on
the number of solute particles and
not on the chemical identity of the
solute

A

Colligative property

99
Q

The decrease in the freezing point of
a liquid caused by adding a solute

A

Freezing-point depression

100
Q

If we add 275 g ethylene glycol, C2H6O2, a nondissociating molecular compound, per 1000 g of water in a car radiator, what will the freezing point of the solution be?

A

8.26°C

101
Q

A 0.89% w/v NaCl solution is referred to as a physiological or isotonic
saline solution because it has the same concentration of salts as normal
human blood, although blood contains several salts and saline solution has
only NaCl. What is the osmolarity of this solution?

A

Osmolarity 0.15 2 0.30 osmol

101
Q

■ Describe how we would make the following
solutions:
(a) 280 mL of a 27% v/v solution of ethanol, C2H5OH,
in water
(b) 435 mL of a 1.8% v/v solution of ethyl acetate,
C4H8O2, in water
(c) 1.65 L of an 8.00% v/v solution of benzene, C6H6,
in chloroform, CHCl3

A

(a) 76 mL of ethanol is dissolved in 204 mL of water
to give 280 mL of solution.
(b) 7.8 mL of ethyl acetate is dissolved in 427 mL of water
to give 435 mL of solution.
(c) 0.13 L of benzene is dissolved in 1.52 L of chloroform
to give 1.65 L of solution.

102
Q

Calculate the w/v percentage of each of these solutes:
(a) 623 mg of casein in 15.0 mL of milk
(b) 74 mg vitamin C in 250 mL of orange juice
(c) 3.25 g of sucrose in 186 mL of coffee

A

(a) 4.15% w/v casein
(b) 0.030% w/v vitamin C
(c) 1.75% w/v sucrose

103
Q

According to the label on a piece of cheese, one serving of 28 g provides the following daily values: 2% of Fe, 6% of Ca, and 6% of vitamin A. The recommended daily allowances (RDA) of each of these nutrients are as follows: 15 mg Fe, 1200 mg Ca, and 0.800 mg vitamin A. Calculate the concentrations of each of these
nutrients in the cheese in ppm.

A

(a) 10 ppm Fe or 1 101 ppm
(b) 3 103 ppm Ca
(c) 2 ppm vitamin A

104
Q

A pill weighing 325 mg contains the following.
What is the concentration of each in ppm?
(a) 12.5 mg Captopril, a medication for high blood pressure
(b) 22 mg Mg21
(c) 0.27 mg Ca21

A

(a) 3.85 104 ppm Captopril
(b) 6.8 104 ppm Mg21 (c) 8.3 102 ppm Ca21

105
Q

Calculate the freezing points of solutions made by dissolving one mole of each of the following ionic solutes in 1000 g of H2O.
(a) NaCl (b) MgCl2
(c) (NH4)2CO3 (d) Al(HCO3)3

A

(a) 23.72°C (b) 25.58°C (c) 25.58°C (d) 27.44°C

106
Q

Methanol, CH3OH, is used as an antifreeze. How
many grams of methanol do we need per 1000 g
of water for an aqueous solution to stay liquid at
220°C?

A

3.4 102 g CH3OH

106
Q

Calculate the osmolarity of each of the following
solutions.
(a) 0.39 M Na2CO3
(b) 0.62 M Al(NO3)3
(c) 4.2 M LiBr
(d) 0.009 M K3PO4

A

(a) 1.2 osmol (b) 2.5 osmol (c) 8.4 osmol
(d) 0.04 osmol

107
Q

A 0.9% NaCl solution is isotonic with blood plasma.
Which solution would crenate red blood cells?
(a) 0.3% NaCl
(b) 0.9 M glucose (MW 180)
(c) 0.9% glucose

A

Red blood cells will undergo crenation (shrink) in
a hypertonic solution. A 0.9% NaCl solution is 0.3 osmol. Solution (b) is 0.9 osmol (hypertonic) and will crenate red blood cells.

108
Q

A reagent label shows that it contains 0.05 ppm
lead as a contaminant. How many grams of lead
are present in 5.0 g of the reagent?

A

3 x10^27 g Pb

109
Q

Which will have greater osmotic pressure:
(a) A 0.9% w/v NaCl solution?
(b) A 25% w/v solution of a non dissociating dextran with a molecular weight of 15,000?

A

(a) 0.9% w/v NaCl has the greater osmotic pressure by a factor of 18 times.

109
Q

m A state in
which the rate of the forward
reaction equals the rate of the
reverse reaction

A

Dynamic equilibrium

110
Q

Some H2 is added to I2 at 427°C and the following reaction is allowed to
come to equilibrium:

H2(g) + I2(g) <====> 2HI(g)

When equilibrium is reached, the concentrations are [I2] 0.42 mol/L, [H2] 0.025 mol/L, and [HI] 0.76 mol/L. Calculate K at 427°C.

A

55

111
Q

Calculate the equilibrium constant for the above reaction (a) with and
(b) without the inclusion of water in the equilibrium expression. The equilibrium concentrations are as follows: [NH3] 0.0100 M; [NH ]0.000400 M; [OH2] 0.000400 M

A

a) 55.56M b)1.60x10^5 M

112
Q

Consider the following equilibrium reaction.
Under each species is its equilibrium concentration. Calculate the equilibrium constant for the reaction.

CO (g) + H2O(g) <====> CO2 (g) + H2O (g)
0.933M 0.720M 0.133M 3.37

A

K= 0.667

113
Q

The following reaction was allowed to reach
equilibrium at 25°C. Under each component is its equilibrium concentration. Calculate the equilibrium constant, K, for this reaction.

2NOCl (g) < =====> 2NO(g) + Cl2(g)
2.6M 1.4M 0.34M

A

K = 0.099 M

113
Q

For the reaction

2NOBr(g) <========> 2NO(g) +Br2(g)

the rate of the reaction was 22.3 mol NOBr/L/h
when the initial NOBr concentration was 6.2 mol
NOBr/L. What is the rate constant of the reaction?

A

rate 0.37/h

113
Q

Ka for benzoic acid is 6.5 1025. What is the pKa of this acid?

A

pKa = - 4.19

113
Q

Which is the stronger acid:
(a) Benzoic acid with a Ka of 6.5 1025 or hydrocyanic acid with a Ka of 4.9 10210?
(b) Boric acid with a pKa of 9.14 or carbonic acid with a pKa of 6.37?

A

a. Benzoic acid is the stronger acid, it has the larger Ka value
b. Carbonic acid is the stronger acid; it has the smaller pKa value

113
Q

What is the pH of a phosphate buffer solution containing 1.0 mol/L of sodium dihydrogen phosphate, NaH2PO4, and 0.50 mol/L of sodium hydrogen phosphate, Na2HPO4?

A

6.91

114
Q

What is the molarity of a solution made by dissolving 12.7 g of HCl in enough water to make 1.00 L of solution?

A

0.348 M

114
Q

Hydronium ion concentrations are generally
expressed in pH units

A

pH= -log [H3O+]
pOH= -log [OH-].

114
Q

What is the pH of a solution if you mix 100 mL of 0.2 M HEPES in the acid form with 200 mL of 0.2 M HEPES in the basic form?

A

7.85

114
Q

Describe how you would prepare each of the following solutions (in each case assume that you have the solid bases).
(a) 400.0 mL of 0.75 M NaOH
(b) 1.0 L of 0.071 M Ba(OH)2

A

(a) 12 g of NaOH diluted to 400 mL of solution
(b) 12 g of Ba(OH)2 diluted to 1.0 L of solution

114
Q

Calculate the pH of an aqueous solution containing the following:
(a) 0.80 M lactic acid and 0.40 M lactate ion
(b) 0.30 M NH3 and 1.50 M NH4+

A

(a) 3.55 (b) 8.55

114
Q

Henderson-Hasselbalch

A

pH = pKa + log [A]/[HA]

114
Q

A solution of an unknown base was titrated with
0.150 M HCl, and 22.0 mL of acid was needed to
reach the end point of the titration. How many moles
of the unknown base were in the solution?

A

3.30 1023 mol

114
Q

A sample of 27.0 mL of 0.310 M NaOH is titrated
with 0.740 M H2SO4. How many milliliters of the
H2SO4 solution are required to reach the end point?

A

5.66 mL

114
Q

What is the molarity of a solution made by dissolving
0.583 g of the diprotic acid oxalic acid, H2C2O4, in
enough water to make 1.75 L of solution?

A

3.70 x10^-3

115
Q

The pKa value of barbituric acid is 5.0. If the H3O1and barbiturate ion concentrations are each 0.0030 M, what is the concentration of the undissociated barbituric acid?

A

0.9 M

115
Q

A tetrahedral atom,
most commonly carbon, at which
exchange of two groups produces
a stereoisomer

A

Stereocenter

115
Q

Suppose you have a phosphate buffer of pH 7.21. If you add more solid NaH2PO4 to this buffer, would you expect the pH of the buffer to increase, decrease, or remain unchanged? Explain.

A

pH = 7.21 + log [HPO4^2-] / [H2PO4^-]
As the concentration of H2PO4- increases, the log becomes negative, lowering the pH and becoming more acidic.

115
Q

A compound whose carbon skeleton can be divided into two or more units identical
to the five-carbon skeleton of isoprene

A

Terpene

115
Q

Chemical Formula of Chlorophyll

A

C55H72MgN4O5

115
Q

Human DNA Empirical Formula

A

C39H50O22N15P3

115
Q

known as London Forces/ instantaneous Dipole induced Dipole forces

A

Van der Waals Forces

115
Q

an intermolecular force resulting from the tendency of polar molecules to align themselves

A

Dipole-Dipole Forces

115
Q

An intermolecular forces commonly observe in molecules that have an -OH or -NH group.

A

Hydrogen Bonding

115
Q

Strongest form of intermolecular force

A

Hydrogen Bonding

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Q
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indiabix (15 decks)

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