Which of the following qualifies as an absolute temperature scale?

a) Fahrenheit

b) Celsius

c) Kelvin

d) none of the above

 Kelvin

The absolute temperature scale defines all other temperatures relative to

the point where all molecules are absolutely still. This theoretical point of no motion is

defined as 0 Kelvin (K), which converts to -273.15 °C.

Which kind of zero is always insignificant?

a) trailing zeros

b) leading zeros

c) zeros found between non-zero digits

d) none of the above

B leading zeros

In sig fig calculations, zeros between non-zero digits (e.g. 101) are always

significant while leading zeros (e.g. 0.1) are always insignificant.

When performing _______, one must round the answer to the lowest number of

significant figures.

a) addition

b) subtraction

c) multiplication

d) none of the above

c) multiplication

Multiplication problems commonly produce excess sig figs. For example,

consider the problem:

3.1 x 4.51 = 13.981

2 sig figs 3 sig figs 5 sig figs

Because an answer cannot be produced with more certainty than the original terms,

one must round the answer to the least amount of certainty present (in this case 2 sig

figs) which yields a final value of 14 after rounding.

Which of the following is not a valid value for scientific notation?

a) 1.0 x 10¹⁴

b) 5 x 10²

c) 62 x 10⁴

d) 6.09 x 10^-17

c) 62 x 10⁴

Scientific notation is always written in the same format. A decimal place is

added after the first digit of any number. Then, this new value is multiplied by 10 with

an exponent that has been adjusted to match the scale of the original number. To be in

correct scientific notation, 62 x 104 must be altered so that the decimal is placed after

the first number, and the exponent should be adjusted accordingly to produce 6.2 x 10 5.

 10⁹ corresponds with which prefix?

a) kilo

b) mega

c) giga

d) tera

c) giga

10⁹, a factor of one billion, is another example of an extremely large value

that can be quickly denoted by the prefix “giga-” to avoid large clunky values and terms.

“Kilo-” (10³⁾, “mega-” (10⁶), and “tera-” (10¹²) refer to factors of one thousand, one

million, and one trillion respectively.

Density is commonly measured in:

a) g/mL

b) g/cm3

c) kg/m3

d) all of the above

d) all of the above

Explanation: Density is the measure of the mass in a given volume. Therefore, the

correct answer must contain units that reflect this relationship. Both grams and

kilograms are measures of mass while mL, cm3, and m3 are all measures of volume,

giving all possible answer choices the desired relationship of mass

volume.

Which is NOT an oxyacid?

a) nitric acid

b) hydrobromic acid

c) sulfuric acid

d) nitrous acid

b) hydrobromic acid

An oxyacid must contain an oxygen atom. Hydrobromic acid (HBr) is a

binary acid composed of only two atoms and neither is an oxygen, so it does not fulfil

the requirement. On the other hand, nitric acid (HNO3), sulfuric acid (H2SO4), and nitrous

acid (HNO2) all contain polyatomic ions that possess oxygens within them.

Which does not qualify as a binary acid?

a) hydrofluoric acid

b) hydrobromic acid

c) hydrochloric acid

d) sulfuric acid

d) sulfuric acid

A binary acid is composed of one acidic hydrogen and one other

nonmetallic element. In this case, hydrofluoric (HF), hydrobromic (HBr), and

hydrochloric (HCl) acid all fulfil this requirement as they are only composed of two

elements, but sulfuric acid (H2SO4) does not as its structure is more complicated.

 Which of the following is perchloric acid?

a) HClO

b) HClO2

c) HClO3

d) HClO4

d) HClO4

Recall that polyatomic ions may have different names based on their oxidation state. For example, observe the difference in oxygen number between

chlorate (ClO3) and perchlorate (ClO4). When naming acids, polyatomic acids with one more oxygen state than their polyatomic ion’s “-ate” suffix will include the prefix “per-”and the suffix “-ic.”

Given an actual yield of 92.1 g, and a theoretical yield of 105.6 g, what is the

percent yield?

A. 14.6%

B. 12.8%

C.87.2%

D. Cannot calculate with the information given

C.87.2%

Percent yield should be calculated in the same way as an exam

grade! A fraction is created by placing the number of questions you actually got correct (actual yield) over the total number of questions you could’ve theoretically gotten correct (theoretical yield) and this value is then multiplied by 100 to achieve a percentage.

% Yield = Actual Yield

Theoretical Yield x 100

% Yield = 92.1 g

105.6 g

x 100

% Yield = 87.2 %

Longer wavelengths correspond with:

a) higher frequencies

b) lower frequencies

c) greater amplitudes

d) smaller amplitudes

b) lower frequencies

Which is an example of a weak electrolyte?

a) NaCl

b) KCl

c) CH4

d) CH3CH2COOH

Explanation: Propionic acid (CH3CH2COOH) possesses an acidic carboxylic acid group

(-COOH), which produces a substantial number of H+ ions but does not fully dissociate.

As a result, this is a weak electrolyte which by definition only partially ionizes. All other

options either fully ionize (NaCl and KCl) or do not ionize at all (CH4).

What are the units of pressure, volume and  temperature for ideal gas equations?

A.  P= atms, V= mL, T= K

B.P= atms, mmHg, V= L, T= K or C

C.P= atms, Pa or mmHg, V= L, T= K

D. P= mmHg or Pa, V= L, T= C

 C. P= atms, Pa or mmHg,  V= L,   T= K

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 Given a mixture of 40.0 g of oxygen and 40.0 g of helium, which exerts a greater

partial pressure?

a) oxygen

b) helium

c) the partial pressure are equivalent

d) impossible to tell

b) helium

Explanation: Pressure depends on the number of particles colliding with the chamber rather than the mass of the particles. Since a helium gas atom (He 4.0 g/mol) has much less mass than a molecule of oxygen gas (O2 32.0 g/mol), more helium atoms will be present in a 40.0 g sample and will yield a higher pressure.

 The partial pressure of F2 in a mixture of gases with total pressure 1.00 atm is 300

torr. What is the mole fraction of F2?

= .395

Remember the molar fraction is calculated by the moles of the element divided by total moles. In this problem they give us pressure so we have to use that to solve the problem. We know that we have 300 torr and 1atm. It is essential that we remember that 1 atm is equal to 760 torr. So know we have the ratio of 300 torr/760 torr for pressure of F₂ over the total pressure that gives us .395

2.2 times faster

The rate of effusion depends only on the mass of the gas particles. This is

simply a plug-and-chug of the effusion equation that solves for the ratio of helium’s

diffusion rate to neon’s.

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2.02 grams/ mole

The rate given is the ratio which compares one gas’s diffusion rate to the other. Therefore, all variables needed in the effusion equation are provided to solve for a second mass after some algebra and rearrangement involving the gas diffusion law.

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 Under which conditions can we no longer treat a gas as an ideal gas?

a) low pressure and low temperature

b) high pressure and high temperature

c) low pressure and high temperature

d) high pressure and low temperature

d) high pressure and low temperature

Explanation: Ideal gases possess no volume or intermolecular attractions and thus the

conditions desired in this question must provide the opposite effect. Under high pressure, gases are forced into closer contact with one another and thus the particles themselves take up a larger part of the chamber. Here, the volume of the particles themselves can no longer be ignored. Additionally, at high speeds and energies, gas particles can easily escape one another’s attractive forces. At low temperatures, gases move lethargically and makes these small attractions significant.

For which gas would behavior deviate from ideal gas behavior the most?

a) CH4

b) CO2

c) H2O

d) F2

c) H2O

Explanation: Ideal gas particles have no intermolecular attractions. The bent shape and strong electronegativity of the oxygen in water creates positive and negative poles

throughout the molecule. Opposite poles attract one another which causes dipole-dipole interactions of significant strength to develop between the molecules. Water in particular possesses especially strong intermolecular attractions in the form of hydrogen

bonds. This consequently causes the gas to stray from ideal behavior.

4) For which gas would behavior deviate from ideal gas behavior the most?

a) H2

b) CH4

c) CH3CH3

d) CH3CH2CH2CH2CH2CH2CH2CH3

d) CH3CH2CH2CH2CH2CH2CH2CH3

Explanation: All molecules listed are composed of only hydrogen and carbon which possess similar electronegativity values and thus do not have strong dipoles. Therefore, the only intermolecular attractions are London dispersion forces which arise from the

random possibility that electrons will be found in the same area during their journey through the electron cloud. With larger molecules, there are simply more electrons which by chance can cluster and create a larger partial charge, thus causing stronger intermolecular attractions. As ideal gases possess no intermolecular attractions, the largest molecule listed, H3CH2CH2CH2CH2CH2CH2CH3, would most strongly deviate from the behavior of an ideal gas.

5) If a relative rate for a reactant with stoichiometric coefficient 2 is x, then for a product

with coefficient 4 it will be:

a) x

b) 2x

c) -x

d) -2x

d) -2x

Explanation: The magnitude of the reaction coefficients indicates that for every 2 particles of the reactant used, four product particles are produced. Therefore, the relative rate of the product’s appearance must be twice the magnitude of the disappearance. On the other hand, the products are appearing while the reactants are disappearing so their rates must have opposite signs.

 The exponents in a rate law:

a) are always equal to the coefficients from the balanced reaction

b) are never equal to the coefficients from the balanced reaction

c) do not correlate with the coefficients from the balanced reaction

If a reaction is first order in A and second order in B, it is _____ order overall.

a) first

b) second

c) third

d) fourth

c) third

The rate law will contain terms representing the concentrations of:

a) reactants only

b) products only

c) both reactants and products

d) none of the above

a) reactants only

Explanation: The rate law illustrates the rate of a reaction which is dependent upon how fast and efficiently reactant molecules collide with one another in a successful reaction to make a product. The product is not involved in the collision of reactants and thus does not affect the rate law.

 The exponents in a rate law must be determined:

a) mathematically

b) deductively

c) quickly

d) experimentally

d) experimentally

Explanation: The only way to determine the exponents in a rate law is through experimentation. For example, if doubling a reactant concentration in the lab causes the rate of a reaction to double, the exponent of that reaction is one (21 = 2) but if the rate quadruples, there must be an exponent of two (22 = 4).

Rate Law = k[A]^?

Given the following reaction, if second order in X and first order in Y, what is the

rate law for the reaction?

X + Y → A + B

Given the following reaction, if X stays the same, Y doubles, and the rate doubles,

the reaction is ____ order in Y.

X + Y →A + B

a) zero

b) first

c) second

d) third

b) first

Explanation: In this reaction, X does not change so Y is the only reactant affecting the reaction rate change. Since the rate is proportional to the change in Y, it must be determined what exponent gives the correct relationship. In this case, the reaction is

first order in Y because doubling Y’s concentration double’s the rate.

Rate Law: r = k [X]^x[Y]^y

r ∝ [Y]^y

2r ∝ [2Y]^y

y = 1

Given the following reaction, if X stays the same, Y doubles, and the rate quadruples, the reaction is ____ order in Y.

X + Y → A + B

a) zero

b) first

c) second

d) third

c) second

Once again, X’s concentration does not change thus the change in

reaction rate is solely dependent on the change in reactant Y. Since the rate is proportional to Y’s concentration raised to some exponent, it can be determined that the reaction is second order in Y because doubling Y’s concentration quadruples the rate.

Rate Law: r = k [X]^x[Y]^y

r ∝ [Y]^y

4r ∝ [2Y]^y

y = 2

What is the molecularity of the following reaction?

A + 2B → products

a) unimolecular

b) bimolecular

c) termolecular

d) none of the above

c) termolecular

Explanation: In the reaction described, three molecules interact. Two molecules of B collide with one molecule of A at the same time to produce the products. As a result of this requirement for three molecules, this is termed a termolecular reaction.

On an energy diagram, the distance from products to the transition state is the:

a) change in enthalpy

b) activation energy

c) reverse activation energy

d) none of the above

 On an energy diagram, the distance from reactants to the transition state is the:

a) change in enthalpy

b) activation energy

c) reverse activation energy

d) none of the above

When plotting linear Arrhenius data, x correlates with the:

a) natural log of the rate constant

b) opposite of the activation energy

c) inverse of temperature

d) natural log of the frequency factor

Explanation: Compare the log-transformed Arrhenius equation to the basic equation for

a line on a graph:

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Which is the only stress that changes the equilibrium constant?

a) change in pressure

b) change in concentration

c) change in volume

d) change in temperature

d) change in temperature

Explanation: It is important to simply memorize that temperature may affect equilibrium.

Given the following reaction and equilibrium concentrations, what is the Kc value?

2A + B ↔ C + 3D

[A] = 0.10 M, [B] = 0.30 M, [C] = 2.0 M, [D] = 1.0 M

Kc = [Products]^p  ÷ [Reactants]^r

K_c = [C][D]^3 ÷ [A]²[B]

Kc = [2.0 M][1.0 M]^3 ÷[0.10 M]²[0.30 M]

Kc = 670

 If water acts as a base, it will become:

a) HO-

b) H3O+

c) H2O

d) none of the above

b) H3O+

Explanation: The options indicate that water either accepted or lost a hydrogen. A Bronsted-Lowry base is defined as a substance which pulls hydrogens from solution. Thus, since H2O has gained a hydrogen atom to become H3O+, water has acted as a base.

 In general, the ______ the conjugate base, the _____ the acid.

a) more stable; stronger

b) more stable; weaker

c) more atoms in; stronger

d) more atoms in; weaker

a) more stable; stronger

Explanation: Consider the strong acid HI. This acid is so strong because the long bond length coupled with the difference in electronegativity between hydrogen and iodine makes the bond very unstable, allowing it to donate hydrogen ions into solution. When a hydrogen breaks off, it is very unlikely that the stable iodine ion (conjugate base) will re-bond to the iodine molecule because the hydrogen would quickly dissociate again. As a result, a stable or weak conjugate base is produced from a strong acid.

Which is the strongest acid?

a) HF

b) HCl

c) HBr

d) HI

d) HI

Explanation: It is important to remember that longer bonds are weaker bonds. Of the halogens listed, iodine has the largest atomic radius. Therefore, its bond with hydrogen

is the longest and thus easiest to break into ions. More dissociation is an indication of a stronger acid which donates more hydrogen ions into solution.

 Which is the strongest acid?

a) HClO

b) HClO2

c) HClO3

d) HClO4

3) D

Explanation: A general rule when determining acid strength is that in comparable species, more oxygens produce a stronger acid. This is because with oxygens are highly

electronegative species which pull electron density towards themselves. The hydrogen is left with very little electron density, making the bond weaker and allowing a hydrogen

ion to pulled off and donated very easily.

Explanation: This problem is simply a plug-and-chug of the pH equation. Remember, hydrochloric acid is strong and thus it completely ionizes. Therefore, the concentration of H+ is identical to the initial concentration of HCl.

pH = − log[H+]

pH = − log[0.14 M]

pH = 0.85

 Explanation: Once again, nitric acid is a strong acid and thus the H+ concentration is identical to the original acid’s. After solving for the pH using the basic formula, the pOH may be found by subtracting this calculated value from 14.

pH = − log[H+]

pH = − log[0.35 M]

pH = 0.46

pOH = 14- pH

pOH = 14 - 0.46

pOH = 13.54

1) Equimolar quantities of strong acid and strong base will yield a _____ solution.

a) acidic

b) basic

c) neutral

d) can’t tell without calculations

4) Equimolar quantities of weak acid and weak base will yield a _____ solution.

a) acidic

b) basic

c) neutral

d) can’t tell without calculations

5) Any neutralization reaction must produce:

a) hydronium

b) hydroxide

c) water

d) none of the above

1) Any buffer solution must consist of a:

a) strong acid or base and its conjugate

b) weak acid or base and its conjugate

c) strong acid and a strong base

d) strong acid and a weak base

b) weak acid or base and its conjugate

Explanation: The purpose of a buffer solution is to minimize changes in pH if additional

acid or base is added. For example, consider:

CH3COOH ↔ CH3COO- + H+

If a strong base such as NaOH is added to this solution, the OH- ions react with the H+ ions to create water. In the original reaction, Le Chatlier’s principle indicates that a

stress which results in less products will cause the equilibrium to shift to the right, maintaining a similar overall pH. The pH value only changes slightly from a small

dilution. This buffering system only occurs when a weak acid or base is present with its conjugate.

3) The pH of the solution at the equivalence point is always:

a) 7

b) above 7

c) below 7

d) depends on the acid and base

d) depends on the acid and base

Explanation: At the equivalence point, equimolar amounts of acid and base are present. In these conditions, if a strong acid and base react, all molecules dissociate and neutralize one another creating a pH of 7. On the other hand, weak acids do not fully ionize whereas strong bases do. Therefore, when titrating a weak acid with a strong base, the weak acid is overpowered, and the equivalence point occurs at a basic pH above 7. The opposite is true for a weak base titrated with a strong acid.

Mn[OH]² ⇆ Mn²⁺ + 2 OH⁻

K_sp = [Mn²⁺][OH⁻]²

 The Ksp for AgCl is 1.8 x 10-10. What is the silver ion concentration in an aqueous

AgCl solution?

First, build an equation displaying the dissociation of AgCl. Then, use the equation for Ksp to solve. Because silver and chloride ions are released in equal concentrations, it is easiest to denote both of their unknown concentrations as “X” when solving.

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