CHEM 122A- Exam 1 Practice Test & Clicker Questions
0.23 ppm: 230 ppb
A solution of SO2 in water contains 0.00023 g of SO2 per liter of solution. What is the concentration of SO2 in ppm? In ppb?
supersaturated
A solution with a concentration higher than the solubility allows is
A greater extent, lowering of the vapor pressure depends on the total solute concentration.
Does adding 1 mol of NaCl to 1 kg of water lower the vapor pressure of water to the same extent, a lesser extent, or a greater extent than adding 1 mol of C6H12O6 to 1 kg of water?
The equilibrium shifts to the left, forming more NO and O2
Does the equilibrium 2 NO(g) + O2(g)↔2 NO2(g) shift to the right (more products) or left (more reactants) if NO is removed?
The equilibrium shifts to the right, using up some of the added O2.
Does the equilibrium 2 NO(g) + O2(g)↔2 NO2(g) shift to the right (more products) or left (more reactants) if O2 is added to the system?
Yes, the half-life of a zero-order reaction is dependent on the initial concentration.
Does the half-life of a zero-order reaction depend on the initial concentration of the reactant?
No, the reaction rate usually depends on concentration but the rate constant does not
Does the rate constant depend on the concentrations of the reactants?
No, the reaction rate usually depends on concentration but the rate constant does not.
Does the rate constant depend on the concentrations of the reactants?
No, as the order of each concentration changes in a rate law, the units of the rate constant change, but those of the rate are always concentration/time.
Does the rate constant have the same units as the rate?
Kc is independent of the starting concentrations of reactants and products.
Does the value of Kc in Equation 15.10 depend on the starting concentrations of NO2 and N2O4?
a homogeneous mixture
All of the following are considered to be colloids except
atomic radii and chemical bonding properties
For a substantial alloy to form, the two metals combined must have similar
Packing efficiency decreases as the number of nearest neighbors decreases.
For metallic structures, does the packing efficiency increase or decrease as the number of nearest neighbors (the coordination number) decreases?
1/Kc
For the reaction PCl5(g)↔PCl3(g) + Cl2(g), the equilibrium constant KC = 1.1 × 10-2 at 400 K. What is the equilibrium constant for the reaction PCl3(g) + Cl2(g) PCl5(g) at 400 K?
The magnitude of the new Kp is the cube of the original Kp.
How does the magnitude of Kp for the reaction2 HI(g)↔H2(g) + I2(g) change if the equilibrium is written 6 HI(g), 3 H2(g) + 3 I2(g)?
increase; lower
A catalyst can ____ the rate of a reaction by providing an alternative pathway with a ____ activation energy
stay the same
If a reaction is carried out in the presence of a catalyst, will the amount of product present at equilibrium increase, decrease, or stay the same?
1.25 g
If a solution containing 10.0 g of a substance reacts by first-order kinetics, how many grams remain after three half-lives?
Molality will be nearly the same as its molarity.
If an aqueous solution is very dilute, will its molality be greater than its molarity, nearly the same as its molarity, or smaller than its molarity?
0.00140 (no units)
If the concentration of N2O4 in an equilibrium mixture is 0.00140 M, what is its activity? (Assume the solution is ideal.)
k[B]
If the rate law for the reaction A+3B→C+2D is zero order in A and first order in B, then the rate law is
Increasing
If you put a drop of food coloring in water and watch the drop disperse, is entropy increasing or decreasing?
increasing
If you put a drop of food coloring in water and watch the drop disperse, is entropy increasing or decreasing?
tetragonal
Imagine you generate a three-dimensional lattice by taking a and b vectors that form a two-dimensional square lattice. then add a third vector c, that is of different length and perpendicular to the first two. Which of the seven three-dimensional lattices results?
Increasing the partial pressures of the reactive components of a gaseous mixture increases the rate of reaction.
In a reaction involving reactants in the gas state, how does increasing the partial pressures of the gases affect the reaction rate?
the rate of crystallization = the rate of dissolution
In a saturated solution of salt in water,
Increasing the amount of vinyl acetate increases the extent of side chain branching and inhibits crystallinity. Decreasing the number of crystalline regions results in a decreasing melting point.
In copolymers made of ethylene and vinyl acetate monomers, melting point and degree of crystallinity decrease as the percentage of vinyl acetate increases. Suggest an explanation. (Image 2)
goes down regardless of whether the reaction is exothermic or endothermic
In general, as activation energy increases, reaction rate
A heterogeneous catalyst is easier to remove from a reaction mixture because of phase differences.
In general, which type of catalyst, homogeneous or heterogeneous, will be easier to recover from the reaction mixture?
No, the hydrophilic groups would be repelled by the hydrophobicity of the lipids.
Some proteins reside in the hydrophobic lipid bilayer of the cell membrane. Would hydrophilic groups of these proteins still be facing the lipid "solvent"?
Lower solubility
Suppose the hydrogens on the OH groups in glucose were replaced with methyl groups, CH3. Would you expect the water solubility of the resulting molecule to be higher than, lower than, or about the same as glucose?
4
The ideal value of i (van't Hoff factor) for Na₃PO₄ is
solvent
The magnitudes of Kf and of Kb depend on the identity of the
M⁻¹ s⁻¹
The overall order of a reaction is 2. the units of the rate constant for the reaction are
polar solvents dissolve polar solutes and non polar solvents dissolve non polar solutes
The phrase "Like dissolves Like" refers to the fact that
weak solvation of Na⁺ and Cl⁻ by C₆H₆
The principal reason for the extremely low solubility of NaCl in benzene (C₆H₆) is the
the reaction is first order overall
The rate law for a reaction is Rate=k[A][B] which one of the following statements is false?
L mol⁻¹ s⁻¹
The rate law of a reaction is rate=k[D][X]. The units of the rate constant are
all of the above - collision frequency, energy, and orientation
The rate of a reaction depends on
primitive cubic
The unit cell with all sides the same length and all angles equal to 90 that has lattice points only at the corners is called
true
True or False: You can determine if equilibrium has been reached by monitoring the concentration of a single reactant.
True. Enzymes act as catalysts and therefore increase the rate of the reaction.
True or false: enzymes lower the energy of the transition state for a reaction.
1/8
What fraction of the volume of each corner atom is actually within the volume of a face-centered cubic unit cell?
The additional solute does not dissolve, and the solution remains saturated.
What happens if a solute is added to a saturated solution?
The equilibrium shifts to the left.
What happens to the equilibrium 2 SO2(g) + O2(g)↔2 SO3(g) if the volume of the system is increased?
Bimolecular
What is the molecularity of the elementary reaction? NO(g) + Cl2(g)→NOCl(g) + Cl(g)
the dispersion of argon atoms produces an increase in disorder
When argon is placed in a container of neon, the argon spontaneously disperses throughout the neon because
Au has the greater number of electrons in antibonding orbitals, and W has the higher melting point.
Which element, W or Au, has the greater number of electrons in antibonding orbitals? Which one would you expect to have the higher melting point?
square
Which of the following lattices is one of the five two-dimensional lattices in which the lattice vectors a and b are equal and the y angle between them is 90?
monoclinic
Which of the following lattices is one of the seven primitive three-dimensional lattices in which the relationship between the lattice vectors a,b, and c can be written as: a ≠b≠c?
the weaker the attraction between the solute and solvent molecules, the greater the solubility
Which of the following statements is false?
CH₃CH₂OH
Which of the following substances is more likely to dissolve in CH₃OH?
the forward and reverse reaction rates
Which of the following variables are equal when the N2O4(g)↔2 NO2(g) reaction reaches equilibrium: (a) kfand kr, (b) the forward and reverse reaction rates, (c) the concentrations of [N2O4] and [NO2]?
CH₃OH
Which one of the following is most soluble in water?
Na₂SO₄
Which one of the following solutes has a limiting van at #39; t Hoff factor (i) of 3 when dissolved in water?
CBr₄
Which one of the following substances is more likely to dissolve in CCl₄?
it is an alloy of silver
Which statement best describes the classification of Sterling silver?
O₂
Which substance in the reaction below either appears or disappears the fastest? 4NH₃ + 7O₂→4NO₂+6H₂O
Odds of three particles simultaneously colliding together and properly oriented are very low.
Why are termolecular elementary steps rare in gas-phase reactions?
NaCl is ionic and ion-ion forces in the lattice are not broken by ion-nonpolar interactions.
Why doesn't NaCl dissolve in nonpolar solvents such as hexane, C6H14?
Interstitial alloy because B has a small size and can occupy "holes" between Pd atoms
Would you expect the alloy PdB0.15 to be a substitutional alloy or an interstitial alloy?
Kp = PH2O(g)
Write the equilibrium-constant expression for the evaporation of water H2O(l)↔H2O(g), in terms of partial pressures.
[NH₄⁺][OH⁻]/[NH₃]
Write the equilibrium-constant expression for the reactionNH3(aq) + H2O(l)↔NH4+(aq) + OH-(aq)
the half-life of a first order reaction does not depend on [A]⁰; the half-life of a second-order reaction does depend on [A]⁰
One difference between first and second-order reactions is that
mol/L
of the following, all are valid units for a reaction rate except
alloy
A metallic material that is composed of two or more elements is called a(n)
increases by a factor of 4
A reaction was found to be second order in carbon monoxide concentration. The rate of the reaction ____ if the [CO] is doubled, with everything else kept the same
Depends on whether the solute is a strong or weak electrolyte
A solute dissolved in water causes the boiling point to increase by 0.51 °C. Does this necessarily mean that the concentration of the solute is 1.0 m?
100 g of the solution contains 11 g of sodium chloride
A solution contains 11% by mass of sodium chloride. This means that
has a concentration lower than the solubility limit
An unsaturated solution is one that
When ions slip past each other, like charges experience repulsions, causing the solid to be brittle
Atoms in metals easily slip past one another as mechanical force is applied; can you think of why this would not be true for ionic solids?
the increase of reaction rates with increase in temperature
Colligative properties of solutions includes all of the following except
a long-range repeating pattern of atoms, molecules, or ions
Crystalline solids differ from amorphous solids in that crystalline solids have
4
In the crystal structure of potassium oxide, the oxide ions are coordinated by eight potassium ions. What is the coordination number of potassium?
ii > i > iii
In the figure, order the following three rates from fastest to slowest: (i) The average rate of the reaction between 0 s and 600 s, (ii) the instantaneous rate at t = 0 s, and (iii) the instantaneous rate at t = 600 s. You should not have to do any calculations.
No, an ionic substance has at least two different atoms, and different atoms cannot lie on the same lattice points.
Is it possible for all atoms in an ionic compound to lie on the lattice points as they do in the metallic structures shown in the illustration?
Yes, if the number of moles of gaseous products equals the number of moles of gaseous reactants
Is it possible to have a reaction where Kc = Kp? If so, under what conditions would this relationship hold?
The osmotic pressure of a 0.10 M solution of NaCl is equal to that of a 0.10 M solution of KBr.
Is the osmotic pressure of a 0.10 M solution of NaCl greater than, less than, or equal to that of a 0.10 M solution of KBr?
A condensation polymer because it has a reactive site H2N−that can react with a −COOH site on another molecule with water also forming
Is this molecule a better starting material for an addition polymer or a condensation polymer? (Image 1)
Endothermic. Raising the temperature of an endothermic reaction shifts the equilibrium to the right, increasing the vapor pressure of the gaseous product.
Is vaporization an exothermic or endothermic process? Based on Le Châtelier's principle, would you predict the vapor pressure of a gas will increase or decrease as the temperature increases?
first
It was determined experimentally that the reaction rate doubled when the concentration of B was doubled in the following reaction: A+B→C. The reaction is ___ order in B.
a).Endothermic b).Exothermic
Label the following processes as exothermic or endothermic: (a)breaking solvent-solvent interactions to form separated particles (b)forming solvent-solute interactions from separated particles
No, by decreasing the size of the particles to form nanocrystals, the band gap and wavelength will decrease, resulting in a shift of emission deeper into UV region.
Large crystals of ZnS can show photoluminescence, emitting ultraviolet photons with energies equal to the band gap energy and a wavelength of 340 nm. Is it possible to shift the luminescence so that the emitted photons are in the visible region of the spectrum by making appropriately sized nanocrystals?
brittleness
Metallic solids exhibit all of the following except
dipole-dipole forces, london dispersion forces, and/or hydrogen bonds
Molecular solids consist of atoms or molecules held together by
Al(NO₃)₃
Of the following, a 0.1 M aqueous solution of ____ will have the lowest freezing point.
The 0.20 m KCl solution is hypotonic with the 0.50 m KCl solution.
Of two KBr solutions, one 0.50 m and the other 0.20 m, which is hypotonic with respect to the other?
No, because B can be isolated, and transition states are by definition not stable.
Suppose we have two reactions, A→B and B→C. You can isolate B, and it is stable. Is B the transition state for the reaction A→C?
The forward rate constant would be larger because the activation energy is less.
Suppose you could measure the rate constants for both the forward and reverse reactions of the process in the figure. In which direction would the rate constant be larger?
3.4x10⁻² mol/L-atm
The concentration of CO₂ in a soft drink bottled with a partial pressure of CO₂ of 6.5 atm over the liquid at 29° C is 2.2x10⁻¹ M. The Henry's law constant for CO₂ at this temperature is
hydrogen bonding between water molecules
The dissolution of water in octane (C8H18) is principally prevented by
The reaction rate will double because the rate law is first order in [H2].
The experimentally determined rate law for the reaction 2 NO(g) + 2 H2(g) N2(g) + 2 H2O(g) is Rate = k[NO]2[H2]. If the concentration of H2 is doubled, will the reaction rate quadruple, double, or remain the same?
NaCl
a 2.05 m aqueous solution of some unknown had a boiling point of 102.1°C. Which one of the following could be the unknown compound? The boiling point elevation constant for water is 0.52 ° C/m
