DAT Chemistry Practice Questions

One of the tanks that a pediatric dentist uses to administer nitrous oxide is "empty", meaning that the N2O inside is at the same temperature and pressure as the room. The ML-6 type cylinder has an internal volume of 165 liters. How many moles of nitrous oxide remain in the empty tank (Ideal gas constant = 0.082 L atm/K mol; assume the apparatus is at sea level; the ambient temperature is 22° C)?

a. 6.8 moles.

b. 0.15 moles.

c. 21.8 moles.

d. 22.4 moles.

e. Zero moles; the tank is empty.

a. 6.8 moles.

PV = nRT

(1 atm)(165 L) = n(0.082 L atm/K mol)(295 K)

n = 6.8 moles

What is the empirical formula of an unknown compound that contains 48.02% carbon, 18.74% hydrogen, and 33.24% nitrogen?

a. C3HN2

b. C31HN25

c. C25HN31

d. C2HN3

e. C5H24N3

e. C5H24N3

A solution is formed by dissolving 12.5g of sucrose in 0.100 kg of water. What is the percent mass of the solute in the solution?

a. 8.0%

b. 11.11%

c. 12.5%

d. 0.8%

e. 125%

b. 11.11%

In a reaction between Mg and Ar, which of the following is most likely to occur?

a. no reaction would occur

b. a precipitate would form

c. a gas would be produced

d. a color change would occur

e. an aqueous solution would form

a. no reaction would occur

Noble gases are inert and do not react under normal conditions.

Calculate the equilibrium constant for the following system:

H2 (g) + I2 (g) ↔ 2 HI (g)

The system initially contains 1.0x10^-3 M H2 and 2.0x10^-3 M of I2. At 448 C, the system reached equilibrium. The concentration of HI at equilibrium is 1.90x10^-3 M.

a. (1.9x10^-3) / (5.0x10^-5)(1.05x10^-3)

b. (5.0x10^-5) / (1.05x10^-3)(1.9x10^-3)

c. (1.9x10^-3)^2 / (5.0x10^-5)(1.05x10^-3)

d. (1.9x10^-3)^2 / (1.0x10^-3)(2.0x10^-3)

e. (1.0x10^-3)(2.0x10^-3) / (1.9x10^-3)

c. (1.9x10^-3)^2 / (5.0x10^-5)(1.05x10^-3)

Which of the following is at the highest energy during an endothermic chemical reaction?

a. reactants

b. products

c. catalyst

d. activated complex

e. intermediates

d. activated complex

During a chemical reaction, enough energy must be absorbed for the reaction to take place. This is termed the activation energy. At the height of the activation energy is the activated complex.

Which of the following elements would contain the valence electron configuration 4s^2 4p^5?

a. Fluorine

b. Sulfur

c. Calcium

d. Bromine

e. Antimony

d. Bromine

If the valence shell ends in the 4th energy level, this means the compound must be in the fourth row of the periodic table. The only element that has 7 valence electrons and is in the 4th row is Bromine (Br).

Which of the following molecules has a bond that is nearest to a pure covalent bond?

a. NaCl

b. MgSO4

c. SiO2

d. N2

e. AgO

d. N2

A purely covalent bond has no difference in electronegativity between the two bonding elements. Thus, N2 is a purely covalent bond.

For a mixture of gasses in a container, the total pressure is equal to ________ because of what law?

a. The pressure of the largest gas, First Law of Thermodynamics.

b. The pressure of the smallest gas, First Law of Thermodynamics.

c. The sum of partial pressure of all gases, Dalton's law of partial pressure.

d. The pressure of the greatest gas, Dalton's law.

e. The sum of the top two gases in the mixture, Dalton's law of partial pressure.

c. The sum of partial pressure of all gases, Dalton's law of partial pressure.

In a mixture of gases, the total gaseous pressure is the sum of the partial pressures of all gases, according to Dalton's law of partial pressure.

The enthalpy of a system of gas is dependent on which of the following?

a. Pressure only

b. Volume only

c. Internal energy only

d. Pressure and volume

e. Pressure, volume and internal energy

e. Pressure, volume and internal energy

The equation that governs enthalpy for a homogenous system (all gas or all liquid) is H = U + PV, where U is internal energy, P is pressure, and V is volume.

The hardest substance known is diamond. Which best describes the structure of a diamond?

a. A 3D network lattice of covalently bonded carbon atoms.

b. A 2D network lattice of covalently bonded carbon atoms.

c. A 3D network lattice of carbon ions held together by ionic bonds.

d. A 3D network lattice of carbon ions in a sea of mobile valence electrons held together by metallic bonds.

e. A 3D network lattice of carbon atoms held together by hydrogen bonding and dispersion forces.

a. A 3D network lattice of covalently bonded carbon atoms.

Diamond is a 3D network lattice of covalently bonded carbon atoms.

Graphite, another allotrope of carbon, is a 2D network lattice of covalently bonded carbon atoms.

Which of the following is the process by which an unstable nucleus is transformed into a more stable nucleus with lower energy?

a. nucleation

b. combustion

c. nuclear decay

d. oxidation

e. nuclear fusion

c. nuclear decay

Nuclear decay involves the splitting of an unstable nucleus and emitting a radioactive particle. This process also decreases the energy of the original element.

Which of the following is the charge of iron in the compound, Fe(SO4)2?

a. +1

b. +2

c. -2

d. +4

e. -4

d. +4

SO4^2- = Sulfate

If sulfate has a charge of -2 and 2 sulfates are present, then this results in a charge of -4. Therefore, if sulfate has a -4 (is looking to gain 4 electrons), then the iron must have a +4 charge (be willing to transfer 4 electrons).

How does the C-N bond in CN^-1 differ from the C-H bond in CH4?

a. The C-H bond is longer because it is a double bond.

b. The C-N bond is longer because it is a single bond.

c. The C-H bond is shorter because it is a double bond.

d. The C-H bond is shorter because it is a triple bond.

e. The C-N bond is shorter because it is a triple bond.

e. The C-N bond is shorter because it is a triple bond.

Single bonds are longer than double bonds, which are longer than triple bonds.

The cyanide ion has which of the following molecular geometries?

a. Linear

b. Trigonal Planar

c. Tetrahedral

d. Trigonal Planar - Bent

e. Tetrahedral - Bent

a. Linear

Cyanide is CN-1 and has 10 valence electrons. The only orientation that works with these elements is with a triple bond between the C and N, with each element having a single pair of non-bonded electrons, giving a linear molecular geometry.

A 1 mol sample of ammonia gas (NH3) at 1 atm and 273 K is compressed to 2 atm. What is the difference in volume before and after compression?

a. 22.4 L

b. 18.5 L

c. 11.2 L

d. 5.91 L

e. 1 L

c. 11.2 L

PV=nRT

(1 atm)V = (1 mol)(0.082 L atm/K mol)(273 K)

V = 22 L

P1 V1 = P2 V2

(1 atm)(22 L) = (2 atm) V2

V2 = 11 L

If 45.1 grams of a solute is added to 302 grams of water to make a 0.65M solution, what is the molar mass of a solute?

a. (45.1 grams)/(0.302 moles)

b. (0.65(.302) grams)/(45.1 moles)

c. (45.1 grams)/(0.65 moles)

d. (0.65 grams)/(0.302 moles)

e. (45.1 grams)/(0.65(.302) moles)

e. (45.1 grams)/(0.65(.302) moles)

M = (mols of solute)/(L of solution)

0.65 = (mols of solute)/(.302 L)

0.65(.302 L) = mols of solute

(45.1 g)/(0.65(.302)moles)

Which of the radioactive decay particles have the lowest penetrating power?

a. proton

b. positron

c. gamma rays

d. beta particles

e. alpha particles

e. alpha particles

In order of increasing penetration power, alpha particles have the lowest, then beta particles, then gamma rays. Protons are not known to have penetrating power and a positron is generally unstable and quickly decomposes, so its penetrating power is considered to be negligible.

Mixture A is formed using KCl and H2O and mixture B is formed using MgCl2 and H2O. If the two mixtures have the same molality, which of the following statements would be true about the boiling point of the mixtures?

a. Mixture A would have a higher boiling point

b. Mixture A would have a lower boiling point

c. Mixture B would have a lower boiling point

d. The mixtures have the same boiling point

e. The mixtures would vaporize at the same rate

b. Mixture A would have a lower boiling point

The two mixtures have the same concentration a.k.a. molality. However, they do have differing ionic solutes.

∆T(boiling) = m x Kb x i, the "I" or vant Hoff factor would be the only variable. The higher the vant Hoff factor, the greater the effect on the boiling point and/or freezing point. The von hoff factor for Mixture A is 2, but for Mixture B is 3.

Which of the following will not dissolve in water?

a. Salt, NACl

b. Ethanol, CH3CH2OH

c. Benzene, C6H6

d. Hydrogen chloride, HCl

e. Acetic acid, CH3COOH

c. Benzene, C6H6

Water is polar and law of solubility is that "Like dissolves Like". Hydrocarbons are always nonpolar, therefore benzene (C6H6) will not dissolve in water.

If an unknown compound is found to have an empirical formula of CH4, which of the following is the molecular formula if the molar mass was determined to be 128 g/mol?

a. CH4

b. CH12

c. C8H12

d. C8H32

e. C12H16

d. C8H32

CH4 = 16 g/mol

128/16 = 8

(CH4)(8) = C8H32

How many degrees of unsaturation are present in the anxiolytic drug Valium (diazepam), molecular formula C16H13ClN2O?

a. 8

b. 9

c. 10

d. 11

e. 12

d. 11

Degree of Unsaturation = (2C + 2 + N - H - X)/2

2(16) + 2 + 2 - 13 - 1 = 22

22/2 = 11

What is the final oxidation number of carbon in the following chemical reaction?

6CO2 + 6H2O → C6H12O6 + 6O2

a. -4

b. -2

c. 0

d. 2

e. 4

c. 0

C6H12O6

Each oxygen = -2 → (-2)(6) = -12

Each hydrogen = +1 → (+1)(12) = +12

Cancels each other out and glucose is neutral, therefore carbon must have an oxidation number of 0.

Which of the following compounds would have the highest boiling point?

a. CH4

b. C2H4

c. C10H24

d. C12H26

e. C22H46

e. C22H46

Non-polar compounds have only London dispersion as their intermolecular force, which is relatively weak in comparison to the other intermolecular forces. However, the strength of London Dispersion increases with higher molecular mass.

According to the ideal gas law at STP, which of the following is the value of the ratio between moles (assume 1 mole), the gas constant R, temperature and the pressure?

a. 1

b. 8.314

c. 20

d. 22.4

e. 44.8

d. 22.4

PV = nRT → V = nRT/P

V = (1 mol)(0.082 L atm/K mol)(273 K)/(1 atm)

V = 22.4 L

Balance the following equation:

Butane + O2 → H2O + CO2

a. 1, 1, 5, 4

b. 1, 6.5, 5, 4

c. 1, 12, 5, 8

d. 2, 12, 10, 8

e. 2, 13, 10, 8

e. 2, 13, 10, 8

C4H10 + O2 → H2O + CO2

Balanced:

2 C4H10 + 13 O2 → 10 H2O + 8 CO2

Placing an inflated balloon in the freezer would result in which of the following?

a. the pressure of the gas would increase

b. the volume of the balloon would increase

c. the number of gas collisions would increase

d. the kinetic energy of the gas particles would decrease

e. the moles of the gas in the balloon would decrease

d. the kinetic energy of the gas particles would decrease

Ballon in freezer, the particles lose kinetic energy as the gas particles slow down and have fewer collisions with each other and the container. As a result, if the internal collisions between the gas particles and the inside of the balloon decrease, the volume of the balloon would also decrease and eventually the balloon would deflate. This is a prime example of Charles' Law.

If the temperature of a gas is quadrupled from 40K to 160K, which of the following accurately describes the change in the average kinetic energy of the gas?

a. average kinetic energy is halved.

b. average kinetic energy is unchanged.

c. average kinetic energy doubles.

d. average kinetic energy quadruples.

e. average kinetic energy triples.

d. average kinetic energy quadruples.

The temperature (in Kelvins) of a gas is directly proportional to the average kinetic energy of the gas. Therefore, if the temperature is quadrupled, so to is the average kinetic energy of the gas.

How is the vapor pressure of a liquid affected if it is boiled in a pressure cooker?

a. it is increased.

b. it is decreased.

c. it stays the same.

d. it increases, then becomes constant.

e. it decreases, then becomes constant.

d. it increases, then becomes constant.

A pressure cooker fixes the atmospheric pressure to be higher than normal. In order for a liquid to boil, the vapor pressure inside of the container must be at least equal to the atmospheric pressure. For higher atmospheric pressures, like in a pressure cooker, the vapor pressure must also increase. Once the vapor pressure equals the environmental pressure of the pressure cooker, it remains constant.

Parallax Error may occur when:

a. A weighing balance is not calibrated.

b. A ruler is not checked against a standard length.

c. A pointer on a meter or surface of a liquid in a buret or pipette is not observed from directly straight on.

d. An object under water is observed at an angle from above the surface.

e. The concentration of an acid to be used in a titration is not first checked against a standard.

c. A pointer on a meter or surface of a liquid in a buret or pipette is not observed from directly straight on.

Parallax Error may occur when a pointer on a meter or surface of a liquid in a buret or pipette is not observed from directly straight on. If they are observed from above or below then the liquid surface or pointer will not be seen to line up with the scale.

TNT explosions are very fast reactions involving the production of enormous quantities of heat and gaseous products. Thermodynamically, explosions are best described as:

a. High entropy, exothermic reactions with a low activation energy.

b. High entropy, endothermic reactions with a low activation energy.

c. High entropy, exothermic reactions with a high activation energy.

d. Low entropy, exothermic reactions with a low activation energy.

e. Low entropy, endothermic reactions with a high activation energy.

a. High entropy, exothermic reactions with a low activation energy.

TNT explosions are very fast reactions (the lower the activation energy the less a reaction is impeded) involving the production of enormous quantities of heat (exothermic) and gaseous products (the production of hot gases from a solid explosive dramatically increases the disorder of the system, thus high entropy).

Which piece of laboratory glassware is best used to measure 1.000 L of solution accurately?

a. Beaker

b. Buret

c. Volumetric pipette

d. Measuring cylinder

e. Volumetric flask

e. Volumetric flask

Beaker: holds liquids, not used for measurements

Buret: accurately measures volumes up to 50.00 mL.

Volumetric Pipette: measures small volumes (5 ml, 10 mL, 20 mL, 25 mL and 50 mL)

Measuring cylinder: measures volumes up to 2 L, but not as accurately as the...

Volumetric flask: specifically prepared to measure larger known volumes with an accuracy of 1 mL in a Liter.

Which of these properties is not a colligative property of a salt solution?

a. Lowering of vapor pressure with increasing concentration.

b. Elevation of the boiling point with increasing concentration.

c. Depression of freezing point with increasing concentration.

d. Osmotic pressure increases with increasing concentration.

e. The lower density of ice than the solution from which it forms.

e. The lower density of ice than the solution from which it forms.

The lowering of vapor pressure, elevation of the boiling point, depression of freezing point and increase in osmotic pressure with increasing solute concentration are all colligative properties of the solution, as they all depend on the concentration of solution only and not the type of solute.

A real gas approaches the behavior of an Ideal Gas when:

a. The gas is under high pressure and low temperature.

b. The gas is under low pressure and low temperature.

c. The gas is under high pressure and high temperature.

d. The gas is under low pressure and high temperature.

e. The gas is at any pressure and temperature, as long as it is a gas it is ideal.

d. The gas is under low pressure and high temperature.

An ideal gas is a gas which obeys the Ideal Gas Laws. Real gases behave ideally when their particles are moving at high speed (high temperature)and there is lots of space between the particles (low pressure).The lower the temperature and higher the pressure the less ideal the gas behaves, especially as it approaches its liquidation point.

Which of the following is an accurate explanation for evaporative cooling?

a. molecules decompose

b. molecules vibrate in place

c. molecules slide across one another

d. molecules release heat to the environment

e. molecules absorb heat from the environment

e. molecules absorb heat from the environment

When a liquid evaporates, it must have enough energy to break the intermolecular forces holding its particles together. To gain enough energy to do this, energy in the form of heat is absorbed from the surrounding environment. This is an endothermic process. If heat is absorbed from the environment, then the environment is left feeling cool as the liquid molecules begin to break their bonds/attractions and evaporate.

The solubility of calcium hydroxide (Ca(OH)2) is given as: S = 1/2{[OH]total - [OH]solvent}

The solubility is a factor of total hydroxide ion in the solution and the solvent hydroxide concentration. The solvent is the liquid in which the calcium hydroxide is dissolved. Which of the following would increase the solubility of calcium hydroxide?

a. Increasing the OH- concentration in solution.

b. Increasing the pressure on the solution.

c. Decreasing the OH- concentration in the solvent.

d. Adding water to the solution.

e. Removing water from the solution.

c. Decreasing the OH- concentration in the solvent.

Solubility is negatively affected by solvent content of OH. The more there is in the solvent, the less solubility the calcium hydroxide is. Thus, we can deduce that decreasing the OH concentration in the solvent will increase solubility.

If 7.000g of a solid displaced 21.0 mL of water when dropped into a graduated cylinder, what is the density of the solid?

a. 0.3 g/mL

b. 0.33 g/mL

c. 0.333 g/mL

d. 0.3333 g/mL

e. 0.3333 g/L

c. 0.333 g/mL

Density = mass/volume

7.000 g / 21.0 mL = 0.333 g/mL

3 sig figs because the 21.0 mL used in the calculation had 3 sig figs

Consider the following aqueous equation:

6 NaI + Ca3(PO4)2 → 2 Na3PO4 + 3 CaI2

If 14 moles of NaI, 8 moles of Ca3(PO4)2, and 6 moles of Na3PO4 are present in a mixture, which one of the following compounds would determine the amount of CaI2 that was produced after 2 hours?

a. NaI

b. Ca3(PO4)2

c. Na3PO4

d. CaI2

e. H2O

a. NaI

14 mols NaI x (3 mols CaI2 / 6 mols NaI) = 7 mols CaI2

8 mols Ca3(PO4)2 x (3 mols CaI2 / 1 mols Ca3(PO4)2) = 24 mols CaI2 mols

NaI produces less mols of our product, so it must be the limiting reagent.

When comparing ^18O and O^-2, which of the following is true?

a. both are neutral

b. both have 8 protons

c. both have 8 neutrons

d. both have 8 electrons

e. both have an atomic weight of 18

b. both have 8 protons

18O and O-2 are both forms of oxygen. The former is an isotope and the latter is an ion. The number of protons within the nucleus of an element does not change.

In the reaction between NH4+ and NO3-, which of the following would be considered the base?

a. NO3-

b. NH4+

c. NH3

d. NH4

e. HNO3

a. NO3-

The base is a proton acceptor, and would therefore add a hydrogen to its chemical formula. Between the two compounds provided, NH4+ would behave as the acid, releasing hydrogen to get back to a zero charge and NO3- would behave as the base accepting the hydrogen to return to its neutral state of HNO3.

The conjugate base of HSO4- is which of the following?

a. SO4

b. SO4^2-

c. HSO4^1-

d. HSO4

e. H2SO4

b. SO4^2-

The conjugate base, according to Bronsted-Lowry's definitions, is the compound that results when a H+ has been donated to the solution. If HSO4- is the acid, then it will donate a H+ to form SO42-, which would be the conjugate base.

The pH of 1 Molar acetic acid is 2.4. By adding sodium acetate, NaCH3COO to the acetic acid a buffer solution is formed. Which statement best describes what occurs in the buffer solution?

a. Addition of the sodium acetate adds acetate ions to the solution and the acetic acid equilibrium reacts by reversing to consume some of the introduced acetate ions, pH will approach 0.

b. Addition of the sodium acetate adds acetate ions to the solution and the acetic acid equilibrium reacts by producing more acetate ions, thus the pH of the solution will approach 7.

c. The addition of the sodium acetate does not affect the acetic acid equilibrium, thus the pH remains at 2.4.

d. Addition of the sodium acetate adds acetate ions to the solution and the acetic acid equilibrium reacts by reversing to consume some of the introduced acetate ions, pH will approach 7.

e. Addition of the sodium acetate adds acetate ions to the solution and the acetic acid equilibrium reacts by producing more acetate ions, thus the pH of the solution will approach 0.

d. Addition of the sodium acetate adds acetate ions to the solution and the acetic acid equilibrium reacts by reversing to consume some of the introduced acetate ions, pH will approach 7.

Le Chatelier's principle: "Any change that affects the position of an equilibrium will cause that equilibrium to shift, if possible, in such a way as to partially oppose the effect of that change."

The Molarity of a solution formed by dissolving 100g of sodium chloride, NaCl, in 500mL of solution is:

a. 100 / (23.0 + 35.5) x 0.500

b. 0.100 / (23.0 + 35.5) x 0.500

c. 100 / (23.0 + 35.5) x 500

d. (23.0 + 35.5) x 0.500 / 100

e. 100 / (11 + 17) x 0.500

a. 100 / (23.0 + 35.5) x 0.500

Molarity = mols/L of solution

Moles = mass/molecular mass

= 100 / (23.0 + 35.5)

Volume (L): 500 mL = 0.500 L

In which situation is water acting solely as a Bronsted-Lowry base?

a. NH3 + H2O → NH4+ + OH-

b. NaCl(s) + H2O → Na+(aq) + Cl-(aq)

c. HNO3 + H2O → NO3- + H3O+

d. CuSO4(s) + 5 H2O → CuSO4.5H2O(s)

e. 2 H2O → H3O+ + OH-

c. HNO3 + H2O → NO3- + H3O+

To act as a Bronsted-Lowry base water must accept a proton from an acid forming the hydronium ion, H3O+. This is the case in HNO3 + H2O -> NO3- + H3O+.

A student has two unknown compounds. He discovers that one of the compounds is acetic acid (C2H4O2). He notes that the second compound has a lower boiling point than acetic acid. Which of the following must be true of the second unknown?

a. The second compound is more sterically hindered than acetic acid

b. The second compound is less hydrogen bonding than acetic acid

c. The second compound has a greater molecular weight than acetic acid

d. The second compound has a lower molecular weight than acetic acid

e. The second compound is basic in nature

b. The second compound is less hydrogen bonding than acetic acid

The boiling temperature of a compound is largely dependent on the steric hindrance of the molecule and its polarity, or hydrogen bonding capability. As steric hindrance and hydrogen bonding increase, boiling point increases. As steric hindrance and hydrogen bonding decrease, boiling point decreases. Initially, it may seem that answer D could be possible. However, a lower molecular weight does not guarantee a lower boiling temperature.

The VSEPR geometry of a molecule of hydrogen cyanide (HCN) is which of the following?

a. Trigonal planar

b. Linear

c. Tetrahedral

d. Octagonal

e. Dihedral

b. Linear

Drawing out the molecule, we see that there are no free electrons on N, meaning that it should be a linear, and not trigonal planar, configuration.

Which of the following is a correct stoichiometric reaction of lead (Pb2+) with chlorine ion?

a. 2 Pb^2+ + 2 Cl- → 2 PbCl

b. Pb^2+ + 2 Cl- → PbCl2-

c. 2 Pb^2+ + 6 Cl- → 2 PbCl3

d. Pb + Cl → PbCl

e. Pb^2+ + 2 Cl- → PbCl2

e. Pb^2+ + 2 Cl- → PbCl2

The correct reaction should have a net charge of zero, and must be stoichiometrically correct (no extra electrons or elements).

When smelling a chemical in a chemistry lab, which of the following is the proper technique?

a. waft the air toward your nose

b. cup the opening with your hands

c. waft the air away from your nose

d. place the container at a 15 degree angle

e. place the container at a 30 degree angle

a. waft the air toward your nose

If it is necessary to smell a chemical in the lab, the proper procedure is to waft the air toward your nose using a cupped hand.

A mixture of gases has a total pressure of 48 atmospheres. If there are a total of 4 gases of varying molecular weights in the mixture and the smallest and largest gases account for 75% of the total pressure, which of the following is the pressure of the remaining gases?

a. 6 atmospheres

b. 12 atmospheres

c. 24 atmospheres

d. 36 atmospheres

e. 48 atmospheres

b. 12 atmospheres

According to Dalton's Partial pressure law, the total pressure of a mixture of gases can be determined by adding the individual pressures of the gas. In this problem, the total pressure is 48 atms and 75% of the pressure is accounted for by the largest and smallest gases. The two remaining gases must there for account for only 25% of the total pressure. Therefore, 25% of 48 is equal to 12.

Which of the following is true for the group 7A elements?

a. They are all diatomic molecules

b. They are all non-metals

c. They are all metalloids

d. They are all gases under standard conditions

e. They all have a valence shell configuration of s2p5

e. They all have a valence shell configuration of s2p5

The group 7A elements are often referred to as the halogens. The only characteristic that is true for all elements in group 7A is that they all have an outer-shell electron configuration of s2p5, resulting in a total of 7 valence electrons.

Monatomic, chemically unreactive gases that possess the stable electron configurations that all Representative elements try to attain by undergoing chemical reactions.

From the description, which Group of the Periodic Table do these elements belong?

a. Group 1 (IA) - Alkali Metals

b. Group 2 (IIA) - Alkaline Earth Metals

c. Group 17 (VIIA) - Halogens

d. Group 18 (VIIIA or O) - Inert Gases

e. Groups 3 - 12 - Transition Metals

d. Group 18 (VIIIA or O) - Inert Gases

The Group 18 (VIIIA or O) - Inert Gases elements, He, Ne, Ar, Kr, Xe and Rn are all monatomic, chemically unreactive gases that possess the stable electron configurations that all Representative elements try to attain by undergoing chemical reactions.

Which of the following alcohols would you expect to be the strongest acid?

a. Br3COH

b. Br2CHOH

c. BrCH2OH

d. CH3OH

e. All alcohols are equally acidic.

a. Br3COH

The strongest acid is the molecule with the most stable conjugate base. In this instance, the tribromomethoxide (A) is the more stable conjugate base by virtue of the three electron withdrawing chlorine atoms (Inductive effect).

In the phrase "SN1 Reaction", what does the "1" indicate?

a. The equilibrium constant

b. The number of products produced

c. The stereochemical outcome

d. The rate order

e. The concentration of the nucleophile

d. The rate order

"SN" stands for nucleophilic substitution and the "1" represents the fact that the rate-determining step is unimolecular.

An aqueous solution of a metal nitrate ("X"NO3) forms a precipitate when magnesium sulfate (MgSO4) is added. However, a separate sample of the metal nitrate does not form any precipitate when mixed with hydrogen perchlorate (HClO4). What could this metal "X" be?

a. Sodium (Na)

b. Zinc (Zn)

c. Lead (Pb)

d. Sulfur (S)

e. Potassium (K)

c. Lead (Pb)

Nearly all compounds containing sodium, potassium, or zinc are soluble, therefore can disregard a, b, and e. Lastly, you could eliminate sulfur (d) by recognizing that it's a nonmetal, not a metal. Therefore, the answer is c. Lead (Pb).

You are performing titrations on several unknown acids. From your efforts you generate several titration curves. If you were told the chemical structure of the putative acids, which acid would correspond to a titration curve with exactly two equivalence points?

a. H2SO3

b. HNO3

c. CH3COOH

d. H3PO4

e. HCl

a. H2SO3

In an acid with one proton, there is one equivalence point; however di- and triprotic acids have more than one acidic hydrogen atom. A titration curve with two equivalence points suggests that the acid has two hydrogen atoms.

An unknown compound is found to have 2 times as much carbon as oxygen, and contains no nitrogen. It has as much hydrogen as carbon and oxygen combined. No other elements have been detected. What is its empirical formula?

a. CO2H2

b. CH2O

c. C2H3O

d. CH4O2

e. C2H5O2

c. C2H3O

If the compound has twice as much carbon as oxygen, then that means the carbon: oxygen ratio should be 2:1. There is as much hydrogen as there is oxygen and carbon combined, there should be 3 units of hydrogen, since there are 2 of carbon and one of oxygen. This gives us the empirical formula C2H3O.

The shape of a crystal is dependent on which of the following?

a. the boiling point of the solid.

b. the internal vapor pressure of the solid.

c. the arrangement of the particles in the solid.

d. the pressure of the particles within the solid.

e. the ambient temperature where the solid forms.

c. the arrangement of the particles in the solid.

The shape of a crystal is dependent on the arrangement/layout of the particles in the solid. The unit cell is the smallest repeating unit of a crystal that retains the crystals shape. The unit cell can either be simple cubic, body-centered, or face-centered.

A titration between a weak acid and a strong base would result in a solution with a pH of?

a. 1.25

b. 4.5

c. 5.5

d. 7.0

e. 10.1

e. 10.1

The conjugate acid of a strong base is a weak acid, however the conjugate base of a weak acid is a strong base. Therefore, the strong conjugate base (from the weak acid) will drive the pH high into the basic region.

Which of the following best describes the relationship between an acid with a pH of 3 and an acid with a pH of 6?

a. pH of 3 is 3x stronger than a pH of 6

b. pH of 6 is 10x weaker than a pH of 3

c. pH of 6 is 3000x weaker than a pH of 3

d. pH of 3 is 1000x stronger than a pH of 6

e. pH of 3 is the same acidic strength as pH of 6

d. pH of 3 is 1000x stronger than a pH of 6

The pH scale is based on factors of 10, with each unit representing 10. There are 3 pH units between pH 3 and pH 6, therefore the difference in strength of the two acids is 103 or a 1000 times difference.

Which of the following is NOT a strong acid?

a. HF

b. HCl

c. H2SO4

d. HNO3

e. All are strong acids

a. HF

Strong acids are acids that are completely ionized in water to produce good electrical conductors. Memorize these common strong acids...HCl, HBr, HI, HNO3, H2SO4, HClO4

The principle quantum number of the atom is symbolized

a. ms

b. ml

c. n

d. l

e. s

c. n

The principle quantum number is the value "n" and can only be a positive whole number integer.

Kinetic Energy is proportional to which of the following?

a. pressure

b. friction

c. molecular mass

d. density

e. volume

c. molecular mass

Moving objects that have the capacity to do work possess kinetic energy. Therefore, KE=1/2 mv2. m = molecular mass and v = velocity. Therefore, the answer to this question is molecular mass.

Arrange the following in decreasing atomic radius: O, S, K, Ca, Mg

a. K, Ca, Mg, S, O

b. K, Mg, Ca, O, S

c. Ca, K, Mg, S, O

d. O, S, Ca, Mg, K

e. S, O, Mg, Ca, K

a. K, Ca, Mg, S, O

Atomic Radius will increase as you move from right to left on the periodic table. It will also increase as you move from top to bottom. So the periodic table will give us the answer.

Assume that 2 cubic feet of air is heated from 0 degrees C to 300,000 degrees C. What volume does the air expand?

a. (300,000 x 2) / (273)

b. (300,000 x 2) / (0)

c. (273 x 2) / (300,273)

d. (273 x 2) / (300,000)

e. (300,273 x 2) / (273)

e. (300,273 x 2) / (273)

Charles' Law is used therefore V1/T1 = V2/T2

(V1 x T2) / T1 = V2 → (300,273 x 2) / (273) = V2

The density of alcohol is 0.8 g/ml. What volume of alcohol would weigh 65.0g?

a. (65.0)(0.8)

b. (65.0)/(800)

c. (0.8)/(65.0)

d. (0.8)(65.0)

e. (65.0)/(0.8)

e. (65.0)/(0.8)

Density = (weight/Volume)

65.0 g x (mL/ 0.8 g)

Which element is the least electronegative?

a. F

b. P

c. Ca

d. Rb

e. Ni

d. Rb

Electronegativity will increase as you move from left to right on the periodic table. It will also increase as you move from bottom to the top. As F is in the upper right of the table, it is the most electronegative.

Convert 93.4 degrees F to degrees C.

a. (9/5)(93.4 + 32)

b. (5/9)(93.4 - 32)

c. (9/5)(93.4 - 32)

d. (5/9)(93.4 + 32)

e. (9/5)(93.4 + 273.15)

b. (5/9)(93.4 - 32)

Degrees C = (5/9) (degrees F - 32)

If a solution boils at 3 degrees K, what is the boiling point on the Fahrenheit scale?

a. (9/5)(-270) + 32

b. (5/9)(-270) + 32

c. (5/9)(3 X 32)

d. (9/5)(270) + 32

e. (9/5)(270) - 32

a. (9/5)(-270) + 32

The temperature in Kelvin = Celsius + 273.

3 = C + 273 → C = -270

Now convert Celsius to Fahrenheit by using this equation: F = (9/5)(degrees C) + 32

F = (9/5)(-270) + 32

When 7.0 g of Si is exploded with 32.0 g of O2 forming SiO2, how many grams of O2 remain uncombined? The reaction equation is Si + O2 -> SiO2

a. 0.75 X 32

b. 0.25 X 32

c. 1.5 X 32

d. 0.5 X 32

e. 1.25 X 32

a. 0.75 X 32

Si and O2 react in a 1:1 ratio. To find out the amount of unreacted O2, calculate the number of moles of Si and O2 present and then subtract the number of moles of Si from the number of moles of O2.

7.0 g Si x (mol/28 g Si) = 0.25 mol Si

32.0 g O2 x (mol / 32 g O2) = 1 mol O2

1 mol O2 - 0.25 mol Si = 0.75 mol O2 remain uncombined

Finally, take this mole amount of O2 and multiply it by the molecular weight of O2 to give you the number of grams of unreacted O2.

0.75 mol O2 uncombined x 35 g = grams of O2 uncombined

The value of Kc = 8.0 in the equation 2 SO2(g) + O2(g) → 2 SO3(g). What is the [SO3] at equilibrium if the [O2] is 2.0 M and the [SO2] is 3.0 M?

a. 8.0 M

b. 12.0 M

c. 4.0 M

d. 14.0 M

e. 2.0 M

b. 12.0 M

Kc = [SO3]^2/ ([SO2]^2 x [O2].

8.0 = x^2/ [(3.0 M)^2 x 2.0 M.)

x = 12.0 M

Which of the following is NOT true of a catalyst?

a. Catalysts will decrease the activation energy of the reaction

b. Catalysts will be influenced by the pH of the substance

c. Catalysts do not change the thermodynamics of the reaction

d. Catalysts cause a change in the equilibrium constant of the reaction

e. Catalysts are never consumed during the reaction

d. Catalysts cause a change in the equilibrium constant of the reaction

A catalyst will increase the rate of a reaction without being consumed by that reaction. It will lower the activation energy of the reaction. However, the equilibrium constant will always remain the same during the reaction.

What is the pressure in a 60 liter container that contains 15 moles of helium gas at a temperature of 25 degrees C?

a. (15 X 0.082 X 298)/(60)

b. (15 X 0.082 X 25)/(60)

c. (60)/(15 X 0.82 X 298)

d. (298)/(15 X 0.082 X 60)

e. (25 X 60)/(15 X 0.082)

a. (15 X 0.082 X 298)/(60)

The ideal gas law states that PV=nRT.

T = (25 C + 273) = 298 K

P = nRT/V → (15 x 0.082 x 298) / (60)

Which of the following scenarios will always produce a spontaneous reaction?

a. Positive ΔH and a positive ΔS

b. Positive ΔH and a negative ΔS

c. Negative ΔH and a positive ΔS

d. Negative ΔH and a negative ΔS

e. None of the above

c. Negative ΔH and a positive ΔS

A reaction will be spontaneous if:

1) it is an exothermic reaction (ΔH is negative)

2) the system becomes more disordered, an increase in entropy (ΔS is positive).

Which of the following elements are isoelectronic?

a. N and P

b. Mg+ and Na

c. K- and Ca+

d. H+ and He

e. F- and O+

b. Mg+ and Na

Isoelectronic is when two species have the same number of electrons. When Mg has a positive charge it is lacking an electron, which makes Na and Mg+ isoelectronic.

What is the molality of a solution prepared by dissolving 0.2 mol of ethanol into 500 g of water?

a. 0.2 mol/kg

b. 0.2 mol/g

c. 0.4 mol/kg

d. 0.4 mol/g

e. 0.02 mol/kg

c. 0.4 mol/kg

Molality = moles of solute / kg of solvent.

Molality = 0.2 mol ethanol / 0.500 kg water

Molality = 0.4 mol/kg

After heating NaNO3, it decomposes into NaNO2 and O2. How much NaNO3 would you have to decompose to produce 1.5 g of O2?

a. [(32/2) x 1.5](85)

b. [(1.5/32) x 2](85)

c. [(85/1.5) x 2](32)

d. [(85/32) x 1.5](2)

e. [(2/1.5) x 32](85)

b. [(1.5/32) x 2](85)

Balance the equation → 2NaNO3 -> 2NaNO2 + O2

(1.5 g O2) x (mol O2/32 g) x (2 mol NaNO3 / 1 mol O2) x (85 g NaNO3 / mol)

What is the mole fraction of NaCl in a solution of made by dissolving 58.5 g of NaCl in 9.0 g of H2O? Molecular weight of NaCl = 58.5 g. Molecular weight of H2O = 18.0 g.

a. 1.5

b. 0.97

c. 0.33

d. 0.67

e. 0.49

d. 0.67

A mole fraction of a compound tells what fraction of 1 mole of solution is due to that particular compound.

Mole fraction of solute = (moles of solute)/(moles of solute + moles of solution)

= 1 mol NaCl / 1 mol NaCl + 0.5 mol H2O

= 1/1.5 = 0.67

What are the oxidation numbers of CaH2?

a. Ca +2, H2 -1

b. Ca +1, H2 -1

c. Ca +2, H2 -2

d. Ca -2, H2 +2

e. Ca -1, H2 +1

a. Ca +2, H2 -1

For atoms, molecules and neutral formulas, the total oxidation number is 0.

Group IIA metals have +2, therefore Ca = +2

In compounds, the oxidation number of H is +1

An atom with an atomic number of 12 and a mass number of 24 consists of:

a. 12 protons, 12 electrons, and 12 neutrons

b. 12 protons, 12 electrons, and 24 neutrons

c. 24 protons, 24 electrons, and 12 neutrons

d. 24 protons, 12 electrons, and 12 neutrons

e. 12 protons, 24 electrons, and 12 neutrons

a. 12 protons, 12 electrons, and 12 neutrons

Atomic number is the number of protons in the nucleus. Mass number is the sum of protons and neutrons.

Consider the following equation which is NOT balanced:

WO3(s) + H2(g) -> W(s) + H2O(l)

How many moles of H2O can be produced from 1.00 mole of WO3?

a. 1.00

b. 2.00

c. 3.00

d. 4.00

e. 5.00

c. 3.00

Balance the equation

→ WO3(s) + 3 H2(g) -> W(s) + 3 H2O(l)

1 mol of WO3 can produce 3 mols of H2O

Mg3 N2 + 6H2 O → 3Mg(OH) 2 + 2NH3

How many moles of NH3 are liberated when 2 moles of Mg3 N2 are reacted with 9 moles of H2 O?

a. 1

b. 2

c. 3

d. 4

e. 5

c. 3

Ratio is 1:6 = Mg2N2:H2O. So 2 moles of Mg3N2 would require 12 moles of H2O to fully react, making H2O the limiting reagent.

9 mol H2O x (2 mol NH3 / 6 mol H2O) = 3 mol NH3

Consider the following equation which is NOT balanced:

KO2(s) + H2O(l) -> KOH(s) + O2(g)

How many grams of KO2 must be provided to react completely with 180.0 g of H2O?

a. 1442

b. 374.9

c. 2755

d. 3289

e. 2899

a. 1442

Balance the equation: 4 KO2 + 2 H2O -> 4 KOH + 3 O2

180 g H2O x (1 mol H2O/18g H2O) x (4 mol KO2/2 mol H2O) x (72 g KO2/1 mol KO2) = 1442 g KO2

A solution is prepared by dissolving 10.0 g of NaOH in sufficient H2O to produce 250 mL of solution. Calculate the molarity of this solution.

a. 0.250 M

b. 0.500 M

c. 0.750 M

d. 1.00 M

e. 1.25 M

d. 1.00 M

Molarity = mols/L

10g NaOH x (1 mol NaOH/40 g NaOH) = 0.25 mol NaOH

250 mL = 0.25 L

Molarity = 0.25 mol/0.25 L = 1 M

Diethyl ether has the formula (C2H5)2O. Calculate the molar mass of this ether.

a. 53.4 g/mol

b. 69.7 g/mol

c. 45.1 g/mol

d. 74.1 g/mol

e. 83.2 g/mol

d. 74.1 g/mol

4 C atoms x 12 = 48

10 H atoms x 1 = 10

1 O atom x 16 = 16

48 + 10 + 16 = 74 g/mol

A solution is prepared by dissolving 25.0 g of ZnSO4 in 100.0 g of H2O. This solution has a density of 1.124 g/mL. Calculate the molarity of this solution.

a. 1.39 M

b. 1.82 M

c. 1.04 M

d. 1.72 M

e. 1.61 M

a. 1.39 M

Density = mass/volume → V = m/D

V = (25g + 100g) / 1.124 g/mL → V = 111 mL or 0.111 L

25 g ZnSO4 x (mol ZnSO4 / 161 g ZnSO4) = 0.155 mol ZnSO4

Molarity = mols/L → 0.155 mols ZnSO4 / 0.111 L = 1.39 M

Which of the following is a strong base?

a. NH3

b. CH3NH2

c. NH2OH

d. KOH

e. None of the above

d. KOH

Memorize these strong bases...LiOH, NaOH, KOH, RbOH, CsOH, Mg(OH)2, Ca(OH)2, Sr(OH)2, Ba(OH)2

As one moves down a column of the periodic table:

a. Electron affinity increases

b. Ionization energy increases

c. Oxidation state will always increase

d. Metallic character increases

e. Atomic radius decreases

d. Metallic character increases

Metallic Character will increase as you move from right to left on the periodic table. It will also increase as you move from top to bottom.

How many moles of hydrogen gas are in a 100 L container if the pressure is 20 atmospheres and the temperature is 27 degrees C? R= .082 liter-atm/mole degrees K.

a. (0.082 X 300)/(20 X 100)

b. (20 X 273)/(0.082 X 100)

c. (20 X 100)/(0.082 X 27)

d. (20 X 100)/(0.082 X 300)

e. (273 X 100)/(0.082 X 20)

d. (20 X 100)/(0.082 X 300)

PV = nRT → n = PV/RT

n = (20 x 100) / (0.082 x (27 + 273))

Find the Molecular formula for the compound with 12.06% of Hydrogen, 71.95% of Carbon, and 15.97% Oxygen

a. C6 H12 O

b. C6 H12O6

c. C6 H6 O H2

d. C4 H10 O H3

e. C3 H6 O3

a. C6 H12 O

% x 100g

= 12 g H → 12 atoms of H

= 72 g C → 72/12 = 6 atoms of C

= 16 g O → 1 atom of O

==> C6 H12 O

A "shell" consists of all orbitals having

a. The same value of n

b. The same value of m and l

c. The same value of n, l, and ml

d. The same value of n, l, and ms

e. The same value of all four quantum numbers

a. The same value of n

Orbitals with the same value of "n" are said to be in the same "shell".

Arrange the following elements from largest to smallest according to their atomic radius : K, Mg, Ca, Cl, F

a. K, Ca, Mg, Cl, F

b. K, Mg, Ca, F, Cl

c. F, Cl, Mg, Ca, K

d. Ca, K, Mg, F, Cl

e. Ca, Mg, K, Cl, F

a. K, Ca, Mg, Cl, F

Atomic Radius will increase as you move from right to left on the periodic table. It will also increase as you move from top to bottom.

Balance the equation Zn + HCl -> ZnCl2 + H2

a. 2Zn + HCl -> ZnCl2 + H2

b. Zn + 2HCl -> ZnCl2 + H2

c. 2Zn + 2HCl -> ZnCl2 + H2

d. Zn + 2HCl -> 2ZnCl2 + H2

e. Zn + 2HCl -> ZnCl2 + 2H2

b. Zn + 2HCl -> ZnCl2 + H2

How many ml of gas are enclosed in a cylinder under a pressure of 760 Torr if the final volume of the gas is 50 ml at 1550 Torr?

a. (50 X 1550)/(760)

b. (760 X 50)/(1550)

c. (760)/(1550 X 50)

d. (1550)/(760 X 50)

e. (1550 X 760)/(50)

a. (50 X 1550)/(760)

P1 V1 = P2 V2 → (760) V1 = (1550)(50)

V1 = (1550 x 50)/760

If 3.24 g of hydrogen occupies 44.2 liters, calculate the density of hydrogen gas in grams per millileter.

a. (3.24)(44.2)

b. (3.24)/(44,200)

c. (44.2)/(3.24)

d. (3.24)/(44.2)

e. (44,200)/(3.24)

b. (3.24)/(44,200)

Density = mass/volume

44.2 L = 44,200 mL

D = 3.24 g / 44,200 mL

Which element is most reactive with Cl?

a. Ca

b. F

c. Al

d. Sr

e. Br

d. Sr

The most reactive will be an elements that has the greatest differences in electronegativity. Which in this case will be found in the lower left area of the periodic table.

Which element is the most electronegative?

a. C

b. F

c. Cl

d. Br

e. I

b. F

Electronegativity will increase as you move from left to right on the periodic table. It will also increase as you move from bottom to the top. As F is in the upper right of the table, it is the most electronegative.

The air in a compartment has a pressure of 700 mm of Hg at 25 degrees C. When placed in the sun the temperature rose to 50 degrees C. What was the pressure in the tank at that time?

a. (323 X 700)/(298)

b. (323)/(700 X 298)

c. (700)/(323 X 298)

d. (298 X 323)/(700)

e. (298)/(700 X 323)

a. (323 X 700)/(298)

The Gay-Lussac Law states that (P1/T1)=(P2/T2)

→ (700/298) = (P2/323)

→ P2 = (700 x 323)/(298)

An element that looses _______, will maintain the same atomic number.

a. Proton

b. Electron

c. Neutron

d. Alpha particle

e. Beta particle

c. Neutron

Atomic number is the number of protons in an element. The loss of a proton will by definition change the atomic number. Electrons and beta particles are the same thing and when they are lost, the atomic number will increase by 1. The loss of an alpha particle will decrease the atomic number by 2.

If you change only the number of electrons in an atom you create a(n):

a. Different element

b. Different atomic number

c. Ion

d. Isotope

e. Different atomic weight

c. Ion

By adding another electron in an atom, you create an anion. By removing an electron from an atom, you create a cation.

Which of the following compounds are held together by ionic bonds? H2O, KBr, MgO.

a. H2O only

b. KBr only

c. H2O and KBr

d. KBr and MgO

e. None of the above

d. KBr and MgO

Ionic bonds are found between non-metals and metals. Hydrogen and Oxygen are both non metals. K and Mg are metals and Br and O are non-metals.