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chem3 Flashcards

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1
Q

What is a redox reaction?

A

any reaction where one or more electrons are transferred from one atom to another.

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2
Q

In a redox reaction, if an atom loses electron, is it being oxidized or reduced?

A

oxidized

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3
Q

In a redox reaction, if an atom gains electron, is it being oxidized or reduced?

A

reduced

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4
Q

What is a reducing agent?

A

atom or molecule that donates electrons to another atom or molecule and is itself oxidized in the process.

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5
Q

what is an oxidizing agent?

A

atom or molecule that accepts electrons and is itself reduced in the process.

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6
Q

In the reaction Fe(s) + H2O(l) –>  H2(g) + FeO(s),

what is the reducing agent, what is the oxidizing agent?

A

Fe is reducing agent as it is being oxidized.

He is oxidizing agent as it is being reduced.

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7
Q

Assign an oxidation state to each of the atoms in each of the following molecules: a) (NH4)2SO4, b) FeCO3, c) H2O2, d) NaH, e) SF6.

A

a) N = -3 ; H = +1 ; S = + 6; O = -2 b) Fe = +2 ; C = +4 ; O = -2 ; c) H = +1 ; O = -1 d) Na = +1 ; H = -1 e) S = +6 ; F = -1.

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8
Q

What is a cell potential?

A

E*cell is the sum of the electrical potentials for the two half reactions that make up an electrochemical cell.

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9
Q

T/F? a) Species for which E° is negative cannot be spontaneously reduced, but are often oxidized; b) The hydrogen half-cell has no affinity for electrons as demonstrated by its electrical potential, E° = 0.00 V; c) based on the half-reactions given in the table above, the potential for Cu(s) to be reduced by one electron is -0.52 V

A

a) false
b) fasle
c) We included this question because it seems to create confusion. Reduction half- reactions can be reversed to give oxidation potentials. In other words, the half-reaction runs in the opposite direction. Notice, however, that the reverse of one of these half-reactions involves the LOSS of one or more electrons as the metal forms the associated metal cation. For some reason, it is common for students to think that reversing the sign of the reduction potential gives the voltage associated with reduction of the solid metal. For the MCAT, just remember that cations (Cu+, Fe2+, etc.) get reduced to form solid metals (Cu(s), Fe(s), etc.), and solid metals get oxidized to form cations, but solid metals are NOT reduced.

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10
Q

What are three rules for cell potential?

A

1) half reactions always come in pairs- one reduction half reaction plus one oxidation half reactions.
2) The oxidation half reaction is the reverse of the reduction half reaction. E* for any oxidation half reaction is simply the negative of E* for the associated reduction half reaction.
3) you cannot add two E* values directly off of a half reaction table.

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11
Q

What redox reaction is found in the last step of the ETC?

A

O2 + 4H+ + 4e- –> 2H2O

E= 1.23V

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12
Q

What is a galvanic cell?

A

convert chemical energy into electrical energy. A current can be spontaneously generated along a wire that connects two metal electrodes submerged in a solution that contains metal ions.

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13
Q

Reduction always happens at the ___ and oxidation always happens at the ____

A

cathode; anode

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14
Q

Is cathode the + or -?

A

+

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15
Q

what is the purpose of the salt bridge in the galvanic cell?

A

the salt bridge connects the circuit, allowing continual flow of electrons from electrode to electrode and then back through the salt bridge via ion diffusion.

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16
Q

Which of the following species can form a spontaneous Galvanic cell with copper, where copper is at the cathode?”

A

Though any two metals can spontaneously react to form a galvanic cell, the question specifically asks for copper to be reduced so the reducing agent (substance being oxidized) needs to have a lower reduction potential.

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17
Q

What is true of galvanic cells but not electrolytic cells?

a) cell potential is always positive
b) cathode = + and anode = -

A

A and B

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18
Q

what is an electrolytic cell?

A

A galvanic cell to which an external voltage is applied, forcing the electrons to flow in the opposite direction.

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19
Q

Where do oxidation occur? anode or cathode?

A

anode(-)

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20
Q

where does reduction occur: cathode or anode?

A

cathode (+)

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21
Q

Which species will be reduced in electrolytic cell?

A

species with lower reduction potential will be reduced.

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22
Q

Is cell potential always positive in an galvanic cell or electrolytic cell?

A

galvanic

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23
Q

Is cell potential always negative in an galvanic cell or electrolytic cell?

A

electrolytic

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24
Q

what is a concentration cell?

A

A special type of galvanic cell; The same electrodes and solution are used in both beakers. In one beaker, the metal is oxidized via its oxidation half-reaction, and in the other beaker it is reduced via its reduction half-reaction.

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25
Q

what is nernst equation?

A

E = E° - (0.06/n)*log[lower]/[higher]; n= moles of electrons transferred

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26
Q

what does E* represent?

A

E° will always equal zero for a concentration cell

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27
Q

Species X has a reduction potential of 0.88 V. Species Y has a reduction potential of 0.23 V. If
an electrolytic cell is constructed using these two metals, which metal will be used at the cathode?

A

In a Galvanic cell, because reduction happens at the cathode, the species with the higher reduction potential would be at the cathode. However, because this is an electrolytic cell we know that the electron flow will be forced in the opposite direction—toward the metal with the lower reduction potential. In this case, that is species Y, so we know that metal Y will be at the cathode.

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28
Q

What is Faraday’s constant?

A

charge on one mole of electrons

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29
Q

what’s difference between faraday and farad?

A

Faraday is an obsolete unit of charge equal to the charge on one mole of electrons. In other words, Faraday’s constant = 1 Faraday. The Faraday has since been replaced by the Coulomb. A Farad is a unit of capacitance.

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30
Q

1) Which of the species shown could be used at the anode to create a spontaneous cell in which zinc is formed at the cathode?
Table 1 Reduction Potentials (E°) for various half-reactions.
Zn2+ + 2e-  Zn(s) Cd2+ + 2e-  Cd(s) Fe2+ + 2e-  Fe(s) Cu2+ + e-  Cu+(s)
A) Fe only
B) Fe, Cd, or Cu
C) Two moles of Fe, Cd, or Cu
D) None of the above
-0.76 V -0.40 V -0.44 V +0.16V

A

D- If zinc must be at the cathode, then it must be the species that is reduced. Therefore, the other species must be oxidized. So, to get the total E° for the cell to be positive (spontaneous) we must add the REDUCTION potential for zinc to the OXIDATION potential for each of the potential candidates. The oxidation potential is simply the value given in the table with the sign reversed. None of the species given, when the sign of their potential is reversed and added to the reduction potential for zinc, result in a positive number. Therefore, answer D is correct.

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31
Q

what is the ideal gas law?

A

PV=nRT

R=.0821 Latm/molK

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32
Q

what are the ideal gas law assumptions?

A

1) gas molecules themselves are of negligible volume compared to the volume occupied by the gas.
2) all intermolecular forces between gas molecules are negligible

3) All collisions between gas molecules are perfectly elastic
4) Gases are made up of a large number of molecules that are very far apart from one another
5) Pressure is due to collisions between gas molecules and the walls of the container
6) All molecular motion is random
7) All molecular motion follows Newton’s laws of motion
8) The average kinetic energy (KE) of gas molecules is proportional to temperature

9) ideal gas molecules have no volume and no intermolecular forces.

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33
Q

What are variables of STP?

A 
AtSTP,thevariablesintheIdealGasLawaredefinedasfollows:
 P=1atm
 V=22.4L
 n=1mole
 R = 0.0821 L*atm/mol*K or 8.31 J/mol*K
 T=273K(0°C)
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34
Q

What is the combined gas law equation?

A

P1V1/T1 = P2V2/T2

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35
Q

What are derivates of the combined gas law equation? charles and boil’s law?

A

Boyles: P1V1=P2V2

Charles: V1/T1 = V2/T2

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36
Q

When does the greatest deviation between ideal gas behavior and real gas behavior occur? why?

A

A) temperature is extremely low –> gas particles occupy less volume.
b) pressure is extremely high –> gas molecule occupy higher volume

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37
Q

Looking at Van Der Waals equation, what concepts does it show?
[P+a’ (n/V)^2] * [(V/n)- b’] = RT

a' = consent represents actual strength of intermolecular attractions
b'= constant that represents actual volume of molecules.
A

1) Increased intermolecular attractions (a’) decrease pressure in real gases. The larger a’ is, the larger the second term will become and therefore the smaller P will be.
2) Increased molecular volume (b’) increases volume in real gases.

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38
Q

The ration given by PV/nRT gives us which two assumptions in major cause of deviation from ideal gas law behavior?

A
  • If PV/nRT > 1 it is due mostly to the molecular volume assumption
  • IfPV/nRT<1 it is due mostly to the intermolecular forces assumption
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39
Q

2) Container A is a sealed reaction vessel containing 8.0 moles of hydrogen gas and 2.0 moles of chlorine gas. Container B is a sealed reaction vessel containing 2.0 moles of hydrogen gas and 8.0 moles of chlorine gas. If the gas mixtures in both containers behave as ideal gases, which of the following is true? (Note: Assume both containers are of equal volume and experience identical ambient temperatures.)
A) The pressure inside Container B will be greater than the pressure inside Container A.
B) The pressure inside Container B will be less than the pressure inside Container A.
C) The total number of moles of gas inside Container A is greater than the total number of moles of
gas inside Container B.
D) The pressure inside both containers will be exactly equal.

A

By definition, any ideal gas behaves in an identical manner, regardless of the actual gas molecule present. In other words, even though chlorine gas is a larger, heavier gas than hydrogen gas, they both are treated as identical “ideal” gas particles. For these reason alone, answer D is correct.

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40
Q

What is the equation for Dalton’s law of partial pressures?

A

Ptotal= P1 +P2 +P3 + …

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41
Q

What does Dalton Law state?

A

that the sum of the partial pressures equals the total pressure. If we add gas 1 (G1) to an existing mixture of three gases, we have increased the partial pressure of Gas 1 and the total pressure, but we have had zero effect on the partial pressure of the other gases. So adding more of Gas 1 increases it smile fraction and mass fraction but not its partial pressure.

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42
Q

What does Graham’s law say about diffusion?

A

the process by which gas molecules spread from areas of high concentration to areas of low concentration due to random motion imparted to them as a result of their kinetic energy and collisions with other molecules.

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43
Q

what does graham’s law say about effusion?

A

Diffusion of gas particles through a pin hole. Pin hole is defined as a hole smaller than the average distance a gas molecule travels between collisions.

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44
Q

What equation represents the effusion/ diffusion of grahams’ law?

A

E1/E2 = sqrt of MW2 / sqrt of MW1

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45
Q

What phase change is melting?

A

solid to liquid

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46
Q

what phase change is freezing?

A

liquid to solid

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47
Q

what phase change is liquid to gas?

A

evaporation

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48
Q

what phase change is gas to liquid?

A

condensation

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49
Q

what is sublimation?

A

solid to gas

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50
Q

what is deposition?

A

gas to solid

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51
Q

what is delta H vaporization?

A

amount of energy in Joules/ mole required to go from liquid to gas OR the energy that must be removed to go form gas to liquid.

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52
Q

In a phase diagram, what is the x and z axis?

A

x- temp

y- pressure

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53
Q

On a phase diagram, what do the lines represent? what do the points represent?

A

lines= where two phases are in equilibrium
Triple point is where all three phases are in equilibrium
Critical point and beyond is where there is no distinction between liquid and gas and the phase is called fluid.

54
Q

What is the heating curve? what are on the axis? what do the lines represent?

A

Graph with Temperature (K or C) vs heat (q) in Joules. more constant variable on x acid.

  • The horizontal sections of the graph represent phase changes. (solid to liquid and liquid to gas)
  • The slope of the lines between these horizontal sections represents the inverse (∆T/Q) of heat capacity (Q/∆T) for that particular phase of the substance.
55
Q

Is there a change in temperature during phase change?

A

no

56
Q 
3) For the majority of substances at their triple point, increasing temperature at constant pressure will result in which of the following transformations?
A) gas, liquid and solid to gas only.
B) gas and liquid to solid only.
C) gas, liquid and solid to liquid only.
D) supercritical fluid to gas only.
A

A

57
Q

What is vapor pressure?

A

Vp is the partial pressure of the gaseous form of a liquid that exists over that liquid when the liquid and gas phases are in equilibrium.

58
Q

How is vapor pressure affected by temperature?

A

Increased temperature increases vapor pressure.

59
Q

How does the addition of non volatile solute affect vapor pressure?

A

Addition of a non-volatile solute decreases vapor pressure.

60
Q

How does addition of volatile solute affect vapor pressure?

A

When a volatile solute is added to a solvent it usually decreases vapor pressure for the same reason that a non-volatile solute decreases vapor pressure. As long as the vapor pressure of the solute is LESS THAN the vapor pressure of pure solvent, addition of the volatile solute will decrease vapor pressure. However, if a solute is added that has a vapor pressure greater than that of the pure solvent, then the vapor pressure of the solution will actually be higher than that of the pure solvent. This can be seen by simple examination of the formula for calculating the vapor pressure of a solution containing a volatile solute: Vp = (XsoluteVpsolute) + (XsolventVpsolvent).

61
Q

what two quantities are equal when a liquid boils?

A

When liquid boils when the vapor pressure of that liquid is equal to atmospheric pressure.

62
Q

What is Raoul’s law on vapor pressure and non volatile solute?

A

VaporPressure w/aNon-VolatileSolute=(molefractionofthepuresolvent,X)*(Vpofthe
pure solvent, Vp°)
Vp = XVp°

63
Q

What is Raoul’s law on total vapor pressure with a volatile solute?

A

Total Vapor Pressure w/a VolatileSolute=(mole fraction of solventVp°of the solvent)+ (mole fraction of the solute Vp° of the solute).
Vp,total = Vp,solvent + Vp,solute = Xsolvent Vp°solvent + Xsolute Vp°solute

64
Q

When is Henry’s law used and what does it say?

A

Primarily used to describe the solubility or partial vapor pressure of gases dissolved in liquid. It is defined in multiple forms:

65
Q

When is Henry’s law used and what does it say?

A

Primarily used to describe the solubility or partial vapor pressure of gases dissolved in liquid. It is defined in multiple forms:

1) Vapor Partial Pressure of solute=(molefractionofsolute)(Henry’sLawConstant)
2) Vapor Partial Pressure of solute=(concentrationofsolute)(Henry’sLawConstant)
3) Vapor Partial Pressure of solute=(concentrationofsolute)/(Henry’sLawConstant)

BASICALLY KNOW THAT HENRY’s LAW SAYS THAT ==> The solubility of a gas in a liquid is directly proportional to the partial pressure of the gas over that liquid

66
Q

What happens to the solubility of a gas dissolved in liquid when you increase the temperature?

A

increased temperature decreases solubility and decreased temperature increases solubility.

67
Q

what happens to solubility of a gas in a liquid when vapor pressure is increases?

A

increases solubility of gas in that liquid

68
Q

What type of gas can easily form homogenous mixtures?

A

Polar and non polar gases.

69
Q

What does boiling point elevation state? what equation is associated with it?

A

The boiling point of a liquid is elevated when a non volatile solute is added according to:

delta T = Kbmi
Kb= constant
m= molality
i= number of ions formed per molecule.

70
Q

What is Freezing point depression and what equation is associated with it?

A

The freezing point of a liquid is depressed when a non volatile solute is added according to:

delta T= Krmi
kr= constant different from Kb

71
Q

What is osmotic pressure? what side will have greatest osmotic pressure? what equation is associated with it?

A

A measure of the tendency of water to move from one solution to another across semi permeable membrane, represented as PI in greek letter.
The side that RECEIVES water via osmosis will have the greatest osmotic pressure.

PI= iMRT
i= # of ions from din solution
M = molarity 
R= gas constant
T= absolute temp
72
Q

In a solution, what is the solvent and what is the solute?

A

solute is what is being added- little of it.

solvent is what the solute is being added in = lots of it

73
Q

What are colloids? are they solutions? If not, what characteristics do they have that make them different from true solutions?

A

Colloids are NOT solutions, they are solvents that contain undissolved solute particle that are too small to be separated by alteration, but are much larger than the solute particles in a true solution.
they scatter light; ex: dust and paint.

74
Q

What is the structure and charge of hydroxide?

A

OH-

75
Q

What is the structure and charge of nitrate?

A

NO3-

76
Q

What is the structure and charge of nitrite?

A

NO2-

77
Q

What is the structure and charge of chlorate?

A

ClO3-

78
Q

What is the structure and charge of chlorite?

A

ClO2-

79
Q

What is the structure and charge of hypochlorite?

A

ClO-

80
Q

What is the structure and charge of perchlorate?

A

ClO4

81
Q

What is the structure and charge of carbonate?

A

CO3 (-2)

82
Q

What is the structure and charge of bicarbonate?

A

HCO3-

83
Q

What is the structure and charge of ammonium?

A

NH4+

84
Q

What is the structure and charge of sulfate?

A

SO4(-2)

85
Q

What is the structure and charge of phosphate?

A

PO4 (-3)

86
Q

What is the structure and charge of manganite?

A

Mn(O)OH

87
Q

What is the structure and charge of permanganate?

A

MnO4-

88
Q

What is the structure and charge of cyanide?

A

CN-

89
Q

What are: salvation, hydration,

hydration number, hydrate, anhydrous, and aqueous.

A

Solvation is a general term for the process where in solvent molecules surround a dissolved ion or other solute particle creating a shell.

Hydration is a specific kind of salvation where in water is the participating solvent. Water molecules, being polar, can surround both negatively and positively charged solutes by directing either their partially-negative oxygen, or partially positive hydrogen, moieties toward the ion.

The hydration number is the number of water molecules an ion can bind via this solvation process, effectively removing them from the solvent and causing them to behave more like an extension of the solute.

A hydrate is an inorganic compound in which water molecules are permanently bound into the crystalline structure. The nomenclature of a hydrate is altered to reflect the presence of water molecules. For example, anhydrous cobalt(II)chloride contains no water, but cobalt(II)chloride hexahydrate [CoCl2∙6H2O] contains six water molecules complexed with each cobalt.

As we see in these two names, the term anhydrous is often applied to a compound that can form complexes with water to differentiate molecules that do not contain water from those that do.

Aqueous refers to any solution for which water is the solvent.

90
Q

what is molarity?

A

moles/ liter(volume)

91
Q

what is molality?

A

moles solute/ Kg solvent

92
Q

what is mole fraction?

A

moles solute/ total moles solution (solute+ solvent)

93
Q

what is mass percent?

A

mass f solute/ total mass of solution x 100

94
Q

what is ppm?

A

mass solute/ total mass solution x 10^6

mg/Kg= mg/L

95
Q

what is normality?

A

of moles of equivalents/ Liter solution

96
Q

What is solution formation?

A

when a solution forms, intermolecular forces between the solute particles must first be broken; then any intermolecular forced between the solvent particles must be broken to make room for the solute. Finally, new intermolecular forces are formed between the solute particles and the solvent particles.

97
Q

When does a solution have negative heat ?

A

if new intermolecular forces formed are greater (stronger and more stable) than the sum of the intermolecular forces that had to be broken, net energy is released.

98
Q

What happens to entropy when a solution forms?

A

The dissolution of a solute into a solution is accompanied by a very large, positive change in entropy. A solid or crystal is highly ordered and the break-up and solvation of that solid into individual molecules represents a significant increase in disorder.

99
Q

Are polar substances solubles in polar solvents?

A

No because “like dissolves like”.

100
Q

What can be said with respect to the molar volume of the following gases? (Assume ideal behavior)

  I. CH4                       
 II. C3H8                      
III. C3H6      
IV. C3H6
A) Gas I has a higher molar volume than the other three. B) Gas I has a lower molar volume than the other three. C) The molar volume of gases II and III differ by roughly 5%.   D) All four gases have the same molar volume.
A

d

101
Q

What is Ksp? what affects it? when can it be observed?

A

Solubility product constant
temperature
saturated solution

102
Q

what is difference between solubility and solubility product constant?

A

Solubility is a measure of “how much” of a solute can be dissolved in a given solute. For example, the solubility of iron(III)chloride in water is 74.4g/100mL. The solubility product constant, or Ksp, is defined as the product of the dissolved ions in a saturated solution (i.e., at equilibrium) raised to their coefficients in the balanced equation.

103
Q

What is the ion product?

A

solubility product- the ion product has the same relationship to Ksp as Q does to Ke.
Ksp is solubility product at equilibrium and ion product is not at equilibrium.
Therefore if ion product is equal to Ksp then the solution must be exactly saturated; if ion product is greater than Ksp then precipitate forms and if ion product is less than Ksp then no precipitate forms.

104
Q

How do you calculate the Ksp?

A

10 write out Ksp

2) substitute Ksp into the expression the value given for Ksp
3) substitute a factor of X into the equation fro the concentration of each ion, using 2x, 3x, etc.. if more than one mole of each ion is produced. Hint: ask yourself, if X moles of the reactant are dissolved, how many moles of each ion will be produced?”)
4) Solve for X- X= solubility of that particular specie.

105
Q

What is the common ion effect and what are spectator ions?

A

The Common Ion Effect is a specific application of Le Chatelier’s principle to solution chemistry. Consider the dissolution of Iron(III)Chloride in water: FeCl3(s)  Fe3+(aq) + 3Cl-(aq). Suppose that enough solute is added to saturate the solution. If sodium nitrate is then added to this solution it would have no effect. However, if NaCl were added, the presence of extra chlorine ions from NaCl would—according to LeChatelier’s Principle—drive the reaction to the left resulting in precipitation. In this example, chloride is considered a “common ion” and the precipitation as a result of its addition is what is referred to as the “Common Ion Effect.” Other ions, such as sodium and nitrate—that do not shift the equilibrium—are considered “spectator ions.”

106
Q

What will happen if a common ion is added to a saturated solution? What will happen if a
spectator ion is added to the same solution?

A

Addition of a common ion will cause precipitation. If a spectator ion is added no precipitation will result.

107
Q

Which compound are known as soluble?

A

nitrate, ammonium, and all alkali metals (Group IA).

108
Q

which compounds are known as insoluble?

A

NSOLUBLE: (unless paired with something from the “always soluble” list above) carbonate, phosphate, silver (Ag), mercury (Hg), and lead (Pb).

109
Q

which compounds are known as insoluble?

A

INSOLUBLE: (unless paired with something from the “always soluble” list above) carbonate, phosphate, silver (Ag), mercury (Hg), and lead (Pb).

110
Q

What is the oxidation state of oxygen in

H2O2 and Fe2(SO4)3?

A

-1, -2

111
Q

The formation of rust on metal is an oxidation process involving water that is catalyzed by the presence of salt. Given this information, which of the following would be expected to have the highest reaction potential, E?

a) old rusted nail
b) polyurethane pipe
c) polymer coated wire
d) stainless steel frying pan

A

Rusting, we are told, is an oxidation process. Thus if something rusts easily it must have a high oxidation potential, which is always associated with a low reduction potential. We are asked which item has the highest reduction potential, so we want something that will NOT rust easily, because we just said that rusting easily = low reduction potential. A stainless steel frying pan is supposed to resist rusting, but is made of steel and so it will eventually rust. A coated wire would also resist rust, but the wire inside will rust if the coating wears off. A polyurethane pipe, however, contains no metal and would therefore never rust; it must have the highest reduction potential of all the items listed.

112
Q

In galvanic cell, make sure to switch signs based on reaction given and table given.

A

if table shows E* for a reduction but your reactions shows oxidation then just inverse sign. see question 8-10 chem #3

113
Q

Which of the following is NOT a difference between a galvanic cell and an electrolytic cell?

  • the sign of the anode and cathode
  • the sign of delta G
  • the external voltage source applied
  • the net gain or loss of electrons.
A

The net gain or loss of electrons.

114
Q

Inside a sealed 45L reaction vessel, a sample of methane gas is completely combusted with O2. The total moles of gases is 3moles. which is partial pressure of CO2?

a) 3atm
b) .33atm
c) .5atm
d) 1.5 atm

A

.5atm

because at STP, pressure is 1 and product is o2 and H2o so .5 atm each

115
Q

Two students are woking next to one another. Student A prepares a reaction in a beaker that evolves NO2 case. One meter away, student B prepares a different reaction in a separate beaker that produces SO2 gas. The student are unaware the gases react to form solid hydroxyl amines. At what point will the two gases meet and react?

a) .85meter from NO2 beaker
b) .85 meters from SO2 beaker
c) .53m from SO2 beaker
d) .53 m form NO2 meter

A

D; This is an example of two gases diffusing through the air and combining to react with one another. This should remind you of the law for diffusion of gases, which states that the ratio of the velocities of two gases is proportional to the INVERSE of the ratio of the square root of their molar mass. This means that VNO2 over the VSO2 is equal to the ratio of the square root of 64 (the MM of sulfur dioxide) over the square root of 46 (the MM of nitrogen dioxide). This simplifies to 8/7. We thus know that nitrogen dioxide travels faster, but only by a very small amount. Answers A and B have one or the other gas traveling many times faster, so these must be incorrect. Answers C and D show that they are very close to one another in speed, which is correct. The nitrogen dioxide is the fastest, so they should react closer to the sulfur dioxide beaker and further from the nitrogen dioxide beaker, or Answer D.

116
Q

Cations formed from transition metals, such as lead cobalt and iron usually form insoluble compounds with other ions in solution. However when they are mixed with nitrate or ammonium ions, no precipitates form. Which of the following provides the best explanation for this observation?

a) both nitrate and ammonium always form soluble compounds in aqueous solutions.
b) Compounds containing nitrate are always soluble due to its ability hydrogen bond with water, while ammonium doe snot react with the metal cations.
c) ammonium is always soluble due to its ability hydrogen bond with water and nitrated into react with the cartons
d) both nitrate and ammonium always form insoluble compounds.

A

B; Answer D is incorrect because the question stem clearly states that a precipitate is NOT formed. If nitrates and ammoniums always formed insoluble compounds then they would have formed an insoluble precipitate in this case too. In fact, they ALWAYS form soluble compounds. Answer A may be tempting, especially since it is true. However, think carefully about what is actually happening here. Cations are added to a solution containing nitrate, a negatively charged anion, and ammonium, a positively charged cation. Two cations will never interact with each other. Thus, saying that ammonium compounds are always soluble does not logically apply because no compound would be formed anyway. Answer C is close to correct, but has the relationships backwards. Answer B is correct. The hydrogen bonding capability of nitrates IS a logical explanation for their solubility and ammonium, being a cation itself, would not react with other cations. You may question whether or not nitrate can form hydrogen bonds because there is no hydrogen directly attached to an F, O or N atom. This does mean that nitrate cannot be a hydrogen bond donor and therefore could not hydrogen bond with itself. However, it can act as a hydrogen bond acceptor. Any F, O or N with a lone pair can act as a hydrogen bond acceptor.

117
Q

Which of the following iron compound i most soluble?

a) FeCl3; Ksp= 1x10^-12
b) FeCl2; Ksp= 1x10^-3
c) FeCl; Ksp= 1x10^-3
d) Fe(No2)3; Ksp= 1x10^3

A

Answer D results in the smallest negative number, which is the largest Ksp and thus the most soluble.

118
Q

Vapor pressure exhibits which of the following characteristics?
I temperature increases vapor pressure
II. addition so non volatile solute lowers vapor pressure
III. boiling occurs when vapor pressure equals atmospheric pressure.

A

ALL THREE

119
Q

Which of the followings NOT true?

a) increasing partial pressure of gas increases solubility
b) increasing temperature increases solubility
c) if Ksp is exceeded the gas comes out of solution
d) decreasing average kinetic energy of gas molecule increases solubility

A

B

120
Q

When a common ion is added to a saturated solution:

a) the equilibrium will be shifted to the right
b) a gas will evolve
c) the solution will become a colloid
d) a precipitate forms

A

D

121
Q

Which is least soluble in water?

a) K2SO4
b) NH4CO3
c) PbNO3
d) CaSO4

A

D

remember that NO3 AND NH4 are ALWAYS soluble and SO4 is more soluble with group I element

122
Q

A precipitate is LEAST likely to form when which of the following ions is added to a solution containing aqueous chloride ions?

A) Ag+
B) Ba2+
C) Pb2+
D) Cs+

A

Choice D is correct. Ionic compounds containing Group 1A metals are always soluble, making Answer D the correct answer. Cs+ and Cl- ions will not form an insoluble compound.

123
Q

The standard reduction potential of the zinc electrode is -0.76 V, while the standard reduction potential of the silver electrode is +0.8 V. Given this data, will Zn(s) be spontaneously plated onto the metal strip in the beaker shown below?

A)No, because Ag+ is a stronger oxidizing agent than Zn2+
B) No, because Zn2+ is a stronger oxidizing agent than Ag+.
C) Yes, because Ag is a stronger reducing agent than Zn2+.
D) Yes, because Zn2+ is a stronger reducing agent than Ag.

A

A-
According to the stem, the reduction potential of the silver half-reaction is +0.8 V, while that of the zinc half-reaction is -0.76 V. This tells us that silver ions are more easily reduced than zinc ions. In order for zinc to be plated onto the silver strip, the Ag(s) atoms must give up electrons to the Zn2+ ions, reducing them to Zn(s). ions, reducing them to Zn(s). This will not occur, because, as the standard reduction potentials indicate, silver ions are more readily reduced than zinc ions.

124
Q

what is oxidation of fluorine?

A

-1

125
Q

what is oxidation of hydrogen?

A

+1

126
Q

what is oxidation of hydrogen with metal?

A

-1

127
Q

what is oxidation of alkali metals?

A

+1

128
Q

what is oxidation of alkali earth metals?

A

+2

129
Q

what is oxidation of group V?

A

-3

130
Q

what is oxidation of group VI?

A

-2

131
Q

what is oxidation of group VII?

A

-1

chem (4 decks)

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