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Pass papers theory Flashcards

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1
Q

What type of motion does ATOMS have?

A

translational motion only

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2
Q

what type of motion does MOLECULES have?

A

translational
vibrational and
rotational motion

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3
Q

First law of thermodynamics can be given as…

A
  • energy can neither be created nor destroyed
  • the energy of an isolated system is constant.
  • ΔE = q + w
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4
Q

the pH at the equivalence point of a weak acid- strong base titration increases

A

… as the Ka decreases

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5
Q

the advantage of using enthalpy rather than internal energy to describe energy changes

A

it provides us with a state function which allows us to focus on heat flow which is easier to measure than the work which accompanies a process.

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6
Q

Reason for using a calorimeter to measure heat changes in a chemical reaction is:

A

to account for all of the heat evolved or absorbed during the reaction

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7
Q

when does entropy increase?

A
  • When a substance changes from a solid to a liquid or
  • from a liquid to a gas or
  • solid dissolves in a solvent or
  • Raising the temperature of a system increases the kinetic energy of molecules or
  • where the number of product molecules is greater than the number of reactant molecules or
  • When a gas expands into a larger volume or into a vacuum.
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8
Q

the internal energy change for a process and the enthalpy change for the same process differ by an amount that is directly related to..

A

the work done on (or by) the system

ΔH = ΔU -PΔV

and PΔV = work

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9
Q

the thermodynamic standard states of any substance

A

25 degrees Celsius and 1 atm

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10
Q

Decrease in the entropy of the system, the entropy change of the surroundings will be:

A

larger than the entropy decrease of the system

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11
Q

Why unsaturated hydrocarbons are more reactive than saturated hydrocarbons?

A

the π component of the C-C double/triple bond is relatively weak.

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12
Q

second law of thermodynamics states

A

for any spontaneous reaction, the entropy of the universe increases

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13
Q

third law of thermodynamics states that…

A

the entropy of a pure, crystalline substance at absolute zero is zero.

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14
Q

when a molecule is heated gently what happens to its molecules?

A

there is an increase in the translational and rotational motion

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14
Q

when an atom is heated gently what happens to its molecules?

A

there is an increase in translational motion only.

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15
Q

For an EXOTHERMIC reaction, if the temperature of a reaction is DECREASED, the effect it will have on ΔG and the equilibrium constant is …

A

ΔG decreases and
K increases

as T and K are directly proportional whereas ΔG and T and inversely proportional

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16
Q

entropy is a measure of?

A

the randomness of a system

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17
Q

what equation relates ΔG and E?

A

ΔG = -nFE

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18
Q

carbon atoms that are bonded to a halide are Electrophilic or nucleophilic?

A

electrophilic

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19
Q

What is electrophilic substitution?

A
  • Electrophilic substitution: An electrophile (something lacking electrons) attacks an electron-rich molecule
  • Often in aromatic rings (like benzene) because they’re electron-rich and attract electrophiles.
  • Adding Br to benzene.
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20
Q

what is nucleophilic substitution?

A
  • A nucleophile (something with extra electrons) attacks an electron-poor spot on a molecule
  • Common in alkyl halides (carbon with halogen) because the halogen makes the carbon electron-poor, which attracts nucleophiles.
  • Replacing Cl in a compound with OH.
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21
Q

the most correct statement about Bronsted lowery acids and Lewis acids are

A

every Bronsted- Lowry acid is also a Lewis acid

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22
Q

Pure water…

A

is a poor conductor of electricity

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23
Q

conjugate acids of weak bases produce

A

more acidic solutions than conjugate acids of strong bases.

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24
Q

what quantities are the properties of a system?

A
  • internal energy
  • temperature
  • enthalpy
  • volume
  • work is NOT part of the system
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25
Q

when a system is in equilibrium

A

the process is not spontaneous in either direction

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26
Q

true or false?
The extent of ionization of a weak electrolyte is increased by
adding to the solution a strong electrolyte that has an ion in
common with the weak electrolyte.

A

False

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27
Q

True or false?
For any buffer system, the buffer capacity depends on the
amount of acid and base from which the buffer is made

A

True.

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28
Q

Which of the salts are acidic?
(a) Ba(CH3COO)2,
(b) NH4Cl, (c) KNO3, (d) Al(ClO4)3.

A

b- NH4Cl and
d- Al(ClO4)3

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29
Q

An acid that have the highest equivalence point is (strong/weak)?

A

weak

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30
Q

Work done on the system by the surroundings leads to a (positive/negative) value?

A

positive value.

ΔE = q + w

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31
Q

how do you calculate the molar heat capacity given the specific heat capacity?

A

molar heat capacity = Cs x molar mass

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32
Q

with thermodynamics one can determine…

A

the temperature at which a reaction will be spontaneous

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33
Q

State functions

A
  • entropy
  • Enthalpy
  • Gibbs free energy
  • internal energy
  • temperature
  • pressure
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34
Q

path functions

A
  • work
  • heat
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35
Q

what process produces the greatest increase in entropy of a substance?

A

vaporizing a liquid

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36
Q

what equation relates temperature and the equilibrium constant?

A

ΔG = -RTlnK
when they are all at standard thermodynamic conditions.

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37
Q

When a real gas under pressure is allowed to expand suddenly (adiabatically)
which changes occur?.

A
  • the temperature drops
  • its entropy increases
  • heat is converted into disorder
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37
Q

A large value of the standard reduction protentional indicate a ________ reaction.

A

spontaneous

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38
Q

How many Chiral carbons does b- glucose have?

A

5 chiral carbons

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39
Q

What product can undergo electrophilic substitution?

A

the benzene ring

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39
Q

Lewis Acid

A
  • accepts an electron pair
  • these are electrophiles
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40
Q

What statement is most consistent for an acid with a pH = 3?The acid is:

A

100 times as strong as an acid with a pH= 5

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41
Q

when dealing with specific heat how will it be affected by the highest final temperature?

A

the one with the lowest specific heat

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42
Q

What Increases for a spontaneous process …

A

the total entropy of the system and surroundings increase

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43
Q

a reaction come to equilibrium when it reaches?

A

its minimum Gibbs energy

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44
Q

True/ False?
a non spontaneous process cannot be caused to occur under any circumstances?

A

False

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45
Q

True/False
a Spontaneous reaction is one that does not require an external energy source to proceed

A

true

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46
Q

The highest entropy will have the ____ molar mass

A

the one with the highest Mm

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47
Q

if a process is exothermic: the entropy of the surroundings:

A

will sometimes increase and sometimes decrease depending on the process

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48
Q

Structure of Benzene

A
  • undergoes electrophilic substitution
  • exhibits resonance
  • delocalized electrons make it very stable
  • carbons are sp2 hybridized and therefore the ring structure is planar.
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49
Q

True/False
An indicator is chosen so that the pKa is more or less equal to the pH at the equivalence point?

A

True.

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50
Q

true/false
A buffer consists of either a weak acid and its salt or a weak base and its salt

A

true

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51
Q

Explain by means of equations what is meant by a competitive reaction using CH3CH2Br

A
  • Competitive reactions occur when a substrate molecule can undergo different types of reactions with the same reagent. Eg substitution or elimination reactions
  • CH3CH2Br + NaOH → CH3CH2OH + NaBr

CH3CH2Br + NaOH → CH2=CH2 + NaBr + H2O

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52
Q

Name two factors that influence the direction of such competitive reactions

A
  • Temperature
  • Structure of the substrate molecule
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53
Q

the major factor determining the increase in acidity of binary acids (HX, where X = F, Cl, Br, I_ going down a column of the period table is:

A

decreasing the H-X bond strength

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54
Q

to find the equilibrium constant given ka and kb we use the formula:

A

Kc = (ka x kb) ÷ kw

NB: Kw = 1.o x 10 ^ -14

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55
Q

Which of each of the following salts will be neutral: (a) Na(CH3COO)2,
(b) NH4Cl, (c) KNO3, (d) MgCl2?

A

KNO3 and MgCl2

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56
Q

When asked to calculate absorbance (A) what are the 2 equations you can use?

A
  • Beer- Lamberts law A = ε x L x C
  • transmittivity relationship : A = -log (T)
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57
Q

When calculating fuel Value we use:

A

mass (g) x Fuel value in KJ/g

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58
Q

I. in an open vessel at constant atmospheric pressure q is equal to?

II. in a closed vessel q is equal to?

A

ΔH = q for and open vessel and ΔE = q for a closed vessel

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59
Q

What is expected to happen to the V and w when the reaction shown below takes place in a thermally-insulated container outfitted with a movable piston at a constant atmospheric pressure of 1 atm?

2 C2H6(g) + 7 O2(g) → 4 CO2(g) + 6 H2O(g)

A

Volume will increase and work will be done BY the system

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60
Q

An ideal gas expands into a vacuum (external pressure = 0) without gaining or losing heat. For this expansion what happens to ΔG?

A

ΔG does not change as there is no work being done (in a vacuum) and no heat gained or lost.

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61
Q

Will the condensation of water vapor be an exothermic or endothermic reaction?

A

exothermic

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62
Q

name the endothermic reactions

A
  • Ice melting
  • water evaporating
  • boiling
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62
Q

for an endothermic reaction when we decrease the temperature what happens to K and ΔG?

A
  • K DECREASES and
    ΔG increases
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63
Q

in which case will work done on the system be positive?

A

When ΔV < 0, because
w = -PΔV

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64
Q

A galvanic cell consists of one half-cell that contains g Ag(s) and Ag+(aq), and one half-cell that contains Cu(s) and Cu2+(aq). What species are produced at the electrodes under standard conditions?

A

Ag(s) is formed at the cathode, and Cu2+ (aq) is formed at the anode.

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65
Q

true/false
the hydroxide ion is a weaker nucleophile than water?

A

false

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66
Q

in an ester what takes the suffix -yl and what takes the suffix -oate?

A
  • yl: comes from the alcohol part and -oate comes from the carboxylic acid part
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67
Q

Which one of the following salts, when dissolved in water, produces the solution with the lowest pH?
A. NaCl
B. KCl
C. MgCl2
D. AlCl3
E. LiCl

A

AlCl3

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68
Q

Which of the following combinations of chemicals could be used to make a buffer solution?
A. HCl / NaOH
B. HCl / NH3
C HCl / H3PO4
D NaOH / NH3
E. HCl / NaCl

A

HCl/NH3

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69
Q

Under what condition(s) is the enthalpy change of a process equal to the amount of heat transferred into or out of the system? ΔH = q
(i) temperature is constant
(ii) pressure is constant
(iii) volume is constant

A

pressure is constant

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70
Q

Which of the following is True? The internal energy of a system can be increased by:
(i) transferring heat from the surroundings to the system
(ii) transferring heat from the system to the surroundings
(iii) doing work on the system

A
  • transferring heat from the surroundings to the system
  • doing work on the system
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71
Q

What is a criterion for spontaneity that holds for any process?

A

ΔS(total) > 0

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72
Q

when ΔG = ΔG° what is happening with the equilibrium constant?

A

Q = 1

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73
Q

when the system performs work On the surroundings is w (positive/negative)?

A

negative

74
Q

what actions change the measured cell potential?

A
  • a change in the pH
  • increasing/ decreasing the pressure at the cathode part
  • increasing the [ion]
75
Q

what does a large NEGATIVE value of the standard reduction potentials indicate?

A

a non-spontaneous reaction

76
Q

An electrolytic cell is a cell in which:

A

a nonspontaneous reaction is forced to occur

77
Q

What would make this statement TRUE?

Carboxylic acids are produced when tertiary alcohols are treated with a
strong reducing agent.

A

carboxylic acids are produced when PRIMARY alcohols are treated with a strong reducing agent such as LiAlH4

78
Q

when asked for the temperature at which a reaction will be spontaneous/ nonspontaneous what equation do you use?

A

T = ΔH° ÷ ΔS°

79
Q

For an endothermic reaction, decreasing temperature will have the following effects on K and ΔG

A

ΔG more positive (increases) and
-decreases 𝐾

80
Q

What is buffer capacity?

A

is the amount of acid/base the buffer can neutralize before the pH begins to change to an appreciable degree.

81
Q

what is meant by fuel value of a substance?

A

It is the amount of heat produced when 1 g of a substance is combusted.

82
Q

when does H= q?

A

under constant pressure (such as in an open system exposed to atmospheric pressure), the heat (q) added to or released from the system equals the change in enthalpy ΔH.

83
Q

the strength of an oxyacid depends on?

A

the electronegativity of the central atom

84
Q

Which one of the binary compounds will have the highest acid strength? HF, HCl, HBr, HI or H2O

A

HI (the halogen with the least H-X bond)

HF is a weak acid

85
Q

What equation do we use to calculate the ratio of an Base: an Acid

A

Handerson hasselbalch
pH = pKa + log [B]/ [A]

86
Q

what does a buffer depend on?

A

large concentrations of a weak acid and a conjugate base

87
Q

What hinders buffer capacity

A

the greater the amounts of conjugate acid-base pair the more resistant is the ratio of their concentrations and hence pH to change.

88
Q

the greater the buffer capacity…

A

the greater the amount of the conjugate acid-base pair

89
Q

what is the optimum pH of any buffer?

A

pH =pka

90
Q

the highest buffering capacity has the (highest/lowest) concentration

A

highest

91
Q

what are the units of Ɛ

A

dm3. mol-1. cm-1

92
Q

The enthalpy change for the reaction: 3C2H2(g )→ C6H6(l) is negative. What can be concluded with regards to the enthalpy?

A

1 mol of C6H6 has LESS enthalpy that 3 mol of C2H2

93
Q

a chemical reaction that is spontaneous will proceed…

A

without outside intervention

94
Q

the first law of thermodynamic can be stated as:

A

ΔE = q + w

95
Q

Which change is always positive when a spontaneous process occurs?

A

ΔS(universe)

96
Q

what equation relates molar enthalpy, entropy and mols

A

ΔS (fusion) = (ΔH x n) ÷ ΔT

97
Q

Fill in:
1. ΔG > 0
2. ΔG = 0
3. ΔG < 0

A
  1. non- spontaneous
  2. at equilibrium
  3. spontaneous
98
Q

how is reactivity influenced in ringed alkanes?

A

Smaller rings have higher ring strain, making them more reactive.

99
Q

Benzene behaves differently from a hydrocarbon which simply contains three
C=C bonds. From a thermodynamic point of view, the hydrocarbon would be
expected to react much more readily with:
A. H2
B. Cl2
C. Br2
D. HCl

A

all of them as they are all addition reactions and you can add them across the double bond

100
Q

can a tertiary amine form hydrogen bonds?

A

no, as there are no hydrogens connected to an electronegative nitrogen.

101
Q

what is the chemical equation when you add KOH to a buffer solution such as acetic acid with sodium acetate?

A

CH3COOH + KOH ⇌ CH3COO- + H20 + K+

102
Q

the magnitude of Kw indicates that…

A

water autoionizes only to a very small extent

103
Q

The hydride ion, H-, is a stronger base than the hydroxide ion, OH-. The product(s) of the reaction of hydride ion with water is/are:

A

OH- + H2

104
Q

Which one of the following 0.1 M solutions has a pH of 7.0?
A. Na2S
B. KF
C. NaNO3
D. NH4Cl
E. NaF

A

NaNO3

105
Q

what is an oxyacid? And how does the the strength increase?

A

an acid that has oxygen attached to a central atom. For oxyacids with the same central atom the acidity increases with the number of oxygen atoms attached to the central atom.

106
Q

What is the strongest acid among the following?
A. HBrO
B. HBrO2
C. HBrO3
D. HBrO4
E. HBr

A

As for HBr, it is a strong acid but not an oxyacid, and in this context of comparing oxyacids, HBrO₄ is the stronger choice due to the increasing oxygen effect

107
Q

What can make a buffer mixture?

A
  • a weak acid and its weak conjugate base or
  • a Strong acid/base with enough of a weak base/ acid
108
Q

Under what condition(s) is the internal energy change( ΔU) of a process equal to the amount of heat transferred into or out of the system? ΔE = q
(a) temperature is constant
(b) pressure is constant
(c) volume is constant

A

constant volume only

109
Q

When a system is at equilibrium is the reverse or forward reaction spontaneous?

A

none. the process is not spontaneous in either direction

110
Q

With thermodynamics one CANNOT determine?

A

the speed of the reaction

111
Q

what can thermodynamics predict about a reaction?

A
  • the direction of a spontaneous reaction
  • the extent of a reaction
  • the value of the equilibrium constant
  • the temperature at which a reaction will be spontaneous
112
Q

does entropy (increase/decrease) going down the group of halogens?

A

DECREASES

113
Q

What feature must a molecule or ion have to act as a Lewis base?

A

it must have an unshared pair of electrons which can be shared with another atom

114
Q

if ΔG° for a reaction is less than zero then K will be…

A

K > 1

115
Q

For which of the following is the standard Gibbs free energy of formation equal to zero?
(a) H2O(l)
(b) O(g)
(c) Cl2(g)

A

Cl2 (g)

116
Q

in an electrolytic cell a (spontaneous/ nonspontaneous) reaction needs to occur?

A

a nonspontaneous reaction is forced to occur

117
Q

Electrolyisis reactions are…

A

reactions in which work is done on the reaction system

118
Q

How do you calculate the pH in a dilution

A
  1. Find the no. of moles in each acid before the dilution (multiply by 2 if its a polyprotic acid)
  2. Add all the moles of the acid to get the total moles of the H+ that it contributed
  3. find the concentration of the H+ after the dilution
  4. Find the pH
119
Q

What will happen if a small amount of HCL is added to a 0.1M solution of HF ( a weak acid)

A

the % ionization of HF (weak acid) will decrease

120
Q

Which technique would be least suitable to separate the following:
A. Brewed coffee from it’s coffee grounds – filtration.
B. Chloroform (bp. 61 oC) from ether (bp. 35 oC) – distillation.
C. Separation of K+
and Ag+
ions – spectrophotometry.
D. The colour pigments of a leaf – chromatography.
E. Water from wet lettuce – centrifugation.

A

c- you cannot separate ions using spectrophotometry as it is used to measure the light absorbed by chemicals

121
Q

what statements are correct regarding indicators?

A
  • the are usually weak acids
  • The pH at which an indicator changes colour depends on the pKa
  • the point at which an indicator changes colour in a titration is termed the end point
  • Bromothymol blue with a pKa of 7.1 is a suitable indicator for a strong acid - base titration
122
Q

specific heat capacity is…

A

the quantity of heat needed to change the temperature of 1.00g of a substance by 1.00K

123
Q

potential engery is measured in?

A

Joules

124
Q

Electrochemical cell (voltaic/ Galvanic)

A
  • converts chemical energy into electrical energy
  • spontaneous rxn
  • Anode is negative (oxidation)
  • cathode is positive (reduction)
  • electrons move from the anode to the cathode in the external circuit
  • electrons supplied by the species getting oxidized
125
Q

Electrolytic cell

A
  • coverts electrical energy to chemical energy
  • non spontaneous rxn (energy has to be supplied)
  • Anode is POSITIVE ( oxidation)
  • cathode is NEGATIVE ( reduction)
  • external batteries supplies the electrons
  • enter through the cathode and exit through the anode
126
Q

according to the third law of thermodynamics, at 0 K there is zero entropy. this is because?

A

The atoms are ordered as there is no KINETIC energy at 0 K

  • temperature always refers to kinetic energy
127
Q

In a voltaic cell electrons always flow from…

A

the Anode to the Cathode

128
Q

What would happen if a small amount of HCL is added to a 0.1M HF?

A

the % ionization of HF will decrease

129
Q

what would happen is you add NaOH to a small amount of HF?

A

the %ionization of HF increases

130
Q

if the pH decreased by 2. this means the concentration…

A

H+ increased by a factor of 100
formula: [H+] NEW / [H+] OLD
** use antilog for this.

131
Q

precipitation is used to separate?

A

ions from each other

132
Q

What energy does not change in a chemical reaction?

A

nuclear energy

133
Q

How to calculate the heat absorbed/ released when given enthalpy? (H)

A

q = H x no. of moles ( H > 0 exothermic rxn)

q = -H x no. of moles ( H < 0 endothermic rxn)

134
Q

the purpose of the salt bridge?

A

to maintain electrical neutrality in the half cells via migration of the ions

135
Q

which of the following salts will give BASIC solutions when placed in water?

A

CH3COOK and Na2S

136
Q

buffers…

A
  • resists changes to pH upon the addition of small amounts of a strong acid/ strong base
  • the way a buffer operates can be explained in terms of le chateliers principle
  • should contain similar concentrations of a weak acid/ base and its conjugate base/ acid
137
Q

if one mole of an acid neutralizes two moles of a base, then:

A

one mole of acid supplies two moles of hydrogen ions to the base

138
Q

Δ H

A
  • negative when exothermic
  • positive when endothermic
  • Δ H = qp
  • when measured at 1 atm the enthaply change is read as Δ H°
139
Q

internal energy

A
  • is the sum of the energies of all atoms or molecules in a system
  • extensive property
  • increases with an increase in temp and mass
  • is dependent on mass
  • is not = 0 at 0 K due to the contribution of the nuclear and electronic energies
  • during a chemical reaction, nuclear energy does not change
140
Q

the internal energy of a system is always increased by?

A

Adding heat to the system

141
Q

relationship between ka and percent ionization is?

A

directly proportional
* the weaker the ka the weaker the % ionized

142
Q

at the equivalence point in an acid/base titration it is always correct to say?

A

Neither the acid nor the base is in excess.

143
Q

Stronger attraction to the stationary phase

A

Longer retention time

144
Q

Stronger attraction to the mobile phase

A

shorter retention time

145
Q

When given the bond energies and asked to calculate the change in enthalpy what formula do we use?

A

ΔH = bonds broken - bonds formed

146
Q

when an exothermic reaction takes place that is spontaneous despite a negative ΔS system is because?

A

ΔS surroundings increases and therefore ΔS universe is positive

147
Q

Calorimeters measure heats of reaction in:

A
  • Styrofoam cup where pressure is constant (coffee keeps pressures from rising)
  • bomb cell calorimeters where volume is constant
148
Q

True or false
Melting or vaporizing a substance at its melting and boiling point respectively is an isothermal process?

A

True

149
Q

true/false
the total amount of energy obtained by a system equals the total amount of energy accumulated by its surroundings

A

false

150
Q

True/ False
Alkanes are the simplest class of organic molecules because they contain no
functional groups.

A

true

151
Q

True/ false
Structural isomers that belong to the same family display the same chemical
and structural properties.

A

False

152
Q

an appropriate description of spontaneity is?

A

whether a reaction can do useful work at a certain temperature

153
Q

the work done by the system during expansion is ______ and the heat ____ by the system is positive.

A

negative, gained

154
Q

does the formation of rust from iron reacting with oxygen lead to an increase or decrease in entropy?

A

decrease in entropy

155
Q

if a system undergoes a reversible isothermal process without the transfer of heat, the temperature at which this process takes place is called?

A

absolute zero

156
Q

a refrigerator is a reverse heat engine which takes place from a ___ temperature vessel, the discharged it to a ____ temperature vessel and ____ an inward flow of energy.

A

low
high
receives

157
Q

True/False
the standard reduction potential E (red) is proportional to the stoichiometric coefficient

A

False, it has no effect

158
Q

What makes carbon such a unique element?

A

to a greater extent than any other element, carbon can bond to itself to form straight chains, branched chains and rings

159
Q

True/ False
Enantiomers contains sp2 hybridized carbon atom with four different groups attached to it

A

FALSE
sp2 hybridization is for geometric isomers

160
Q

Homologous series

A

a series of compounds belonging to the same functional group with different lengths of the carbon chains

161
Q

An alkene opens to give you what hybridization?

A

sp3

162
Q

LiAlH4:

A

This is a strong reducing agent, used to reduce aldehydes and ketones to alcohols. It’s not suitable for oxidation reactions.

163
Q

PCC (Pyridinium Chlorochromate):

A

This is a mild oxidizing agent that can oxidize primary alcohols to aldehydes without further oxidation to carboxylic acids. This is the reagent most suitable for an oxidation reaction

164
Q

OsO4:

A

This is a strong oxidizing agent that can cleave alkenes to form diols. It’s not suitable for this reaction

165
Q

K2Cr2O7/H+

A

This is a strong oxidizing agent that can oxidize primary alcohols to carboxylic acids. It would over-oxidize the alcohol in this case.

166
Q

KMnO4

A

This is also a strong oxidizing agent that can oxidize primary alcohols to carboxylic acids. It would also over-oxidize the alcohol.

167
Q

WHat reaction would an aromatic hydrocarbon like benzene easily undergo?

A

Friedel crafts acylation

168
Q

strong and weak nuclear forces

A
  • strong nuclear forces hold the nucleus together
  • weak nuclear forces are responsible for alpha and beta decay and play essential roles in splitting the nucleus of an atom
169
Q

what is the relationship between enthalpy and internal energy?

A

ΔH = ΔE + PΔV

170
Q

what is the relationship between the exponent of the concentration of the [OH-] and [H3O+] to its pOH/ pH respectively

A

its the same e.g. [H+] = 1x 10^-4.5 M , thus the pH= 4.5

171
Q

for a conjugate acid/base pair…

A

the pKa + pKb = 14

172
Q

is the carbon in organometals nucleophilic or electrophilic?

A

nucleophilic

173
Q

a buffer that has a pH < 7 can be prepared by?

A

mixing approximately equal amounts of a weak acid and a salt of its conjugate base

174
Q

according to the second law of thermodynamics

A

G system decreases in a spontaneous change at constant temperature and
pressure.

175
Q

What is a surfactant?

A

compounds that lower the surface tension between two liquids

176
Q

what is a zwitterionic surfactant?

A

they have both cationic and anionic centers attached to the same molecule

177
Q

Micelle

A
  • an aggregate of surfactant molecules dispersed in a liquid colloid
  • its formation is essential for the transport of complicated lipids within the human body
178
Q

Amphiprotic/ amphoteric

A

substances that can act as an acid or a base

179
Q

polyprotic

A

a substance that can donate more than 1 proton

180
Q

Which one of the following is NOT an amphoteric species in water?
A. H2CO3
B. HPO42─
C. HS─
D. H2O
E. HSO4─

A

H2CO3

181
Q

electrostatic potential energy properties

A
  • is measured in Joules.
  • As an electron gets closer to the nucleus of an atom its PEel decreases.
  • can have both positive and negative values
  • PEel = q1q2 (where q1 and q2 are the charged particles and r is the 4r distance between them,  is the permittivity of the medium).
  • it is a scalar quantity
182
Q

What are the conditions for when work is being done by the system on the surrounding?

A
  • when there is an increase in the number of gas molecules.
  • The formation of a gas from a solid results in an increase in the number of gas molecules, leading to work being done by the system on the surroundings
183
Q

According to the second law of thermodynamics, for a spontaneous change,
what is always INCORRECT?

A

ΔS (total) < 0

184
Q

Which nucleophiles requires the presence of an acid catalyst
in order to undergo an addition reaction with an aldehyde?

A
  • water
  • ethanol
185
Q

the empirical formula of an addition polymer is…

A

the same as that of the monomer from which it is formed

186
Q

benzene is immiscible in water because of:

A

weak solute-solvent interactions

187
Q

the substance with the highest BP has the highest…

A

dipole moment

188
Q

a typical emulsifying agent has?

A

a hydrophobic group and a hydrophilic group at opposite ends of the molecule

chemistry (5 decks)

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