Regents Chemistry Review Questions
Atomic Theory & Isotopes
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Describe the Gold Foil Experiment.
What is an alpha particle?
What were two conclusions of the Gold Foil Experiment?
The nucleus of an atom consists of 8 protons and 6 neutrons. How many electrons are in this atom?
What is an isotope?
What is common among all the isotopes of a given element?
What is the number of protons in an atom of C-14?
What is the number of neutrons in an atom of C-14?
What is the number of electrons in an atom of C-14?
Element X exists as three naturally occurring isotopes: 97% of the isotopes have a mass of 43amu; 2% have a
mass of 44amu; 1% have a mass of 45amu. What is the average atomic mass for element X?
11. What is the name of the modern (accepted) model of the atom?
12. Where are electrons located in the modern model of the atom?
Periodic Table
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What do all the elements in a period have in common?
What do all the elements in a group have in common?
What is a term that means “attraction for electrons”?
Which atom has the strongest attraction for electrons (greatest electronegativity)?
Explain why the elements nitrogen and phosphorus have similar chemical properties.
Label the following as either increasing or decreasing as you proceed across a period and down a group:
a. atomic radius
c. electronegativity
b. metallic character
d. ionization energy
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What are the seven elements that exist as diatomic molecules?
What are the six elements that exist as monatomic gases at STP?
What is an ion?
What kinds of atoms tend to lose electrons and become positive ions? (metals or nonmetals)
Because they lose electrons, positive ions are (smaller or larger) than the atoms from which they form.
What kinds of atoms tend to gain electrons and become negative ions? (metals or nonmetals)
Because they gain electrons, negative ions are (smaller or larger) than the atoms from which they form.
The ionic radius of which element is smaller than its atomic radius? (Cl, Na, F, O)
The ionic radius of which element is larger than its atomic radius? (I, Ga, Nb, Zr)
Naming and Chemical Formulas
1. Write the chemical formulas for the following substances:
a. mercury (I) fluoride
b. sodium oxide
c. the thiosulfate ion
d. titanium (III) oxide
2. Name the following substances:
a. Mn2O3
f. Al(OH)3
b. CO2
g. HCl
c. CO
h. H3O+
–
d. OH
i. HCN
e. H2SO4
j. KI
3. How many moles of oxygen are there in one mole of C6H12O6?
4. What is the ratio of elements in the compound H2O2?
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h.
nitrogen (IV) oxide
ammonium carbonate
calcium hydroxide
sulfuric acid
k. BeBr
l. C2H4
m. NaHCO3
Bonding, Polarity, and Electron Configurations
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How do you determine if a bond is polar, nonpolar, or ionic?
Describe the polarity of the bonds in a molecule of methane.
Describe the polarity of a molecule of methane.
Which of the following compounds is polar? (NaCl, KI, HF, CO2)
Draw the electron dot structure for a molecule of water.
A water molecule is best described as…
nonpolar with polar covalent bonds
polar with nonpolar covalent bonds
nonpolar with nonpolar covalent bonds
polar with polar covalent bonds
22. Draw the electron dot structure for hydrobromic acid.
23. Draw the Lewis dot structure for magnesium bromide.
24. In an experiment, a student determined the normal boiling points of four unknown liquids. The collected data
were organized into the table below.
A – 9 ºC
B – 31 ºC
C – 80 ºC
D – 100 ºC
Which liquid has the weakest attractive forces between its molecules?
25. List the following liquids in terms of intermolecular forces, in order from the weakest to the strongest:
(ethanol, ethanoic acid, water, propanone)
26. Which molecule contains a triple bond? (N2, Cl2, H2, O2)
27. Why do elements form chemical bonds with one another?
28. As a chemical bond forms between two hydrogen atoms, the potential energy of the atoms is
lower and compound is unstable
lower and compound is stable
higher and compound is stable
higher and compound is unstable
29. Which type of bond has the greatest bond energy? (single, double, triple)
30. What is hydrogen bonding?
31. What is another name for the stable electron configurations listed on the Periodic Table?
32. What does it mean if an electron is “excited”? Did it absorb or release energy?
33. Write the electron configuration for an atom of phosphorus in the excited state.
34. How do we know that when an excited electron “falls” back down to a lower energy state, it releases energy?
35. What do we call the light energy emitted when an excited electrons falls to a lower energy state?
Physical vs. Chemical Changes
1. How are elements and compounds similar? How are they different?
2. In the boxes below, draw particle diagrams to represent an element, a compound, and a mixture using the key
provided.
Element X
The Compound X2Y
A mixture of Element X and Y
Key:
Element X:
Element Y:
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Argon is an example of a(n) (element, compound, mixture)
Salts, such as sodium chloride, are examples of (elements, compounds, mixtures)
Solutions are examples of (elements, compounds, mixtures)
Air is an example of a(n) element, compound, solution)
Which of the following are examples of pure substances?
bromine
air
NaCl(aq)
water
Ca(OH)2
carbonic acid
NaCl(s)
neon
What are examples of physical changes?
What are examples of chemical changes?
Which of the following cannot be broken down chemically? (H2O, O2, Na, ZnCl)
Which of the following can be broken apart chemically? (As, Xe, Mo, HI)
Which of the following can be decomposed by chemical means? (silicon, methanol, radon, mercury)
How do you separate the elements in a compound? (physically, chemically)
How do you separate the pure substances that make up a mixture? (physically, chemically)
What process would you use to separate a mixture of AgCl and H2O?
What process would you use to separate water and alcohol (two liquids)?
How would you separate the salt and water in a salt water solution?
Stoichiometry
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Which represents the greatest mass of fluorine? (1 gram, 1 molecule, 1 mole, 1 atom)
What is the molecular formula of a compound whose empirical formula is CH4 and molecular mass is 64g/mol?
What is the gram-formula mass of AgCl?
What is the mass of 3.5 moles of O2?
What is the total number of sodium atoms in 46.0g of sodium?
The following balanced reaction occurs between copper metal and aqueous solution of silver nitrate.
2 AgNO3 (aq) + Cu (s)  Cu(NO3)2 (aq) + 2 Ag (s)
Given 50 grams of AgNO3:
a)
b)
c)
d)
What is the minimum number of moles of Cu(s) needed to produce 4 moles of Ag(s)?
Calculate the number of moles of AgNO3
Using the mole-to-mole ratio, determine the number of moles of copper (II) nitrate produced
Calculate the number of grams of copper (II) nitrate produced
Thermochemistry (Heating and Cooling Curves)
1. What is another term for “average kinetic energy”?
2. What is standard temperature?
3. In the boxes below, draw particle diagrams to represent a substance in the solid, liquid, gas, & aqueous phases.
Solid
Liquid
Gas
Aqueous
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Which phase has the highest entropy? (solid, liquid, gas)
Which has more entropy? (NaCl (s), NaCl (aq))
At STP, which elements are solids, liquids, gases? (hydrogen, nitrogen, argon, carbon, mercury, bromine, iodine)
What is the equivalent of -33°C in Kelvin?
What is the equivalent of 300 K in Celsius?
The temperature of a substance changes from -173°C to 0°C. How many Kelvin degrees does this change
represent?
10. Be able to interpret and label a heating/cooling curve:
* REMEMBER THE 3 P’S: PLATEAU, PHASE CHANGE, POTENTIAL ENERGY CHANGE
* DIAGONAL PARTS: TEMPERATURE IS CHANGING…THEREFORE THE KINETIC ENERGY IS CHANGING
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Describe what’s happening between intervals
a. AB
c. CD
e. EF
b. BC
d. DE
State whether the following phase changes are endothermic or exothermic.
a. freezing
c. boiling/vaporizing
e. subliming
b. melting
d. condensing
What is specific heat capacity?
What is the specific heat capacity of water?
What is the specific heat capacity of copper if it takes 849 J of energy to change the temperature of 95.4g of
copper from 25 °C to 48 °C?
The temperature of a sample of water changes from 10. °C to 20. °C when the water absorbs 420 Joules of heat.
What is the mass of the sample?
How many Joules of heat are released when 50. grams of water are cooled from 70. °C to 60. °C?
How many Joules are required to melt 225 g of ice at 0 °C?
How many Joules does it take to vaporize 423g of water at 100 °C?
Determine the total amount of heat released by 5.00 grams of water vapor when it condenses.
How many kilojoules of heat must be removed to freeze 35 g of water at 0 °C?
When atmospheric pressure is 0.5 atm, at what temperature does ethanoic acid boil?
Gas Laws & Kinetic Molecular Theory
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What are the four assumptions (parts) of the Kinetic Molecular Theory?
Under what conditions of temperature and pressure are real gases most like ideal gases?
Under what conditions of temperature and pressure do gases deviate most from ideal?
When an air bag in an automobile inflates, the nitrogen gas inside of it is at a pressure of 1.30 atmospheres, a
temperature of 301 K, and a volume of 40.0 liters. Calculate the volume of the nitrogen gas at STP.
5. A sample of gas occupies a volume of 50.0 milliliters in a cylinder with a movable piston. The pressure of the
sample is 0.90 atmosphere and the temperature is 30ºC. What is the volume of the sample at STP?
6. Avogadro’s hypothesis states that under conditions of STP, equal volumes of gases have equal (numbers of
particles, masses, densities)
Solutions and Solubility
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In a solution of salt water, what is the solute? What is the solvent?
What is molarity?
What is the symbol for molarity?
Describe how you would prepare 2L of a 10M sodium chloride solution.
Describe how you would make a 0.5M solution of BaNO3 given 1L of 5M BaNO3.
What is a precipitate? Is it soluble or insoluble?
Write the chemical reaction that occurs when solutions of sodium chloride and silver nitrate are mixed together.
Does a precipitate form? If so, name the precipitate.
Write the chemical reaction that occurs when solutions of ammonium sulfide and sodium hydrogen carbonate
are mixed together. Does a precipitate form? If so, name the precipitate.
What happens to the boiling point of a solution as more solute is added?
What happens to the freezing point of a solution as more solute is added?
Which solution will have the highest boiling point? (2M Ca(OH)2, 2M NaCl)
Which solution will have the lowest freezing point? (0.5M NaCl, 1M NaCl)
How many grams of potassium chloride will dissolve in 100 g of water at 90 ºC?
How many grams of ammonia will dissolve in 200g of water at 10 ºC?
A solution contains 90g of KNO3 at 40 ºC. Is this solution unsaturated, saturated, or supersaturated?
A saturated solution of sodium nitrate is cooled from 50 ºC to 10 ºC. What is the mass of NaNO3 that will
precipitate out of solution?
A saturated solution of KClO3 is heated from 0 ºC to 100 ºC. How many grams of KClO3 must be added to make a
saturated solution at 100 ºC?
Potential Energy Diagrams & Collision Theory
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What are the three main parts of Collision Theory?
What are the six factors that can affect the rate (speed) of a chemical reaction?
What is activation energy?
How does a catalyst speed up a chemical reaction?
What is heat of reaction?
What is the symbol for heat of reaction?
What is the amount of heat absorbed when 2 moles of NaCl(s) is dissolved in water?
Is dissolving solid NaOH in water an endothermic or exothermic process?
How much heat is released when 3 moles of sodium hydroxide dissolve in water?
Is the formation of water from its elements endothermic or exothermic?
What does a potential energy diagram show?
12. Be able to label and interpret a potential energy diagram.
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a. Label the heat of reaction for the reaction above.
b. Calculate the heat of reaction.
c. Is this reaction endothermic or exothermic?
d. Label the activation energy of the forward reaction.
Draw a potential energy diagram for an exothermic reaction. Label the activation energy of the forward
reaction and label the heat of reaction.
What is another name for enthalpy?
What is another name for entropy?
Systems in nature tend to go toward ________________ energy and ________________ entropy.
Which of the following reactions will happen spontaneously?
Cl2(g) + 2NaBr(aq) → Br2(l) + 2NaCl(aq)
Cl2(g) + 2NaF(aq) → F2(g) + 2NaCl(aq)
I2(s) + 2NaBr(aq) → Br2(l) + 2NaI(aq)
I2(s) + 2NaF(aq) → F2(g) + 2NaI(aq)
18. Given the following chemical reaction: Fe(s) + 2HNO3(aq) → Fe(NO3)2(aq) + H2(g)
Explain, using information from Reference Table J, why this reaction is spontaneous.
Equilibrium & LeChatlier’s Principle
1. Saturated solutions are examples of substances in a state of physical equilibrium. What two things are equal to
each other in saturated solutions?
2. At chemical equilibrium, what is equal?
3. What does LeChatlier’s Principle say?
4. What happens to the concentration of a gas if the pressure is increased?
5. What happens to the concentration of a gas if the pressure is decreased?
6. Given the following reaction at equilibrium:
2 CO(g) + O2(g)
a. Which reaction will be favored if…
i. CO is removed from the system?
ii. carbon dioxide is added to the system?
iii. the pressure is decreased?
2CO2(g) + heat
b. What will happen to the system if…
i. a catalyst is added?
ii. the temperature is increased?
iii. more oxygen is added?
7. Given the following reaction at equilibrium:
H+(aq) + OH–(aq)
H2O (l)
∆H = -55.8 kJ
a. What will happen to the system if…
i. H2O is removed from the system?
ii. heat is added to the system?
iii. the pressure is decreased?
b. If a base is added to the system,
i. What will happen to the amount of H+?
ii. What will happen to the amount of
water?
8. Nitrogen gas, hydrogen gas, and ammonia gas are in equilibrium in a closed container at constant temperature
and pressure. The equation below represents this equilibrium.
N2(g) + 3H2(g)
2NH3(g)
The graph below shows the initial concentration of each gas, the changes that occur as a result of adding H2(g)
to the system, and the final concentrations when equilibrium is re-established.
a. What information on the graph indicates that the system was initially at equilibrium?
b. Explain, in terms of LeChatelier’s principle, why the final concentration of NH3(g) is greater than the initial
concentration of NH3(g).
c. Explain, in terms of collision theory, why the concentration of H2(g) begins to decrease immediately after more
H2(g) is added to the system.
Nuclear Chemistry
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What does it mean if a substance is radioactive?
What is an alpha particle?
What is a beta particle?
What is a positron?
What is the decay mode of strontium-90?
Write the nuclear equation for the spontaneous decay of strontium-90.
What is strontium-90 used for?
Write the nuclear equation for the decay of iodine-131.
What is I-131 used for?
Write the nuclear equation for the decay of cobalt-60.
How many protons, neutrons, and electrons does the element formed from the transmutation of Co-60 contain?
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What is Co-60 used for?
What is the half-life of a radioactive isotope if 1/8th of the original sample remains after 50 days?
What fraction of a 300g sample of Au-298 Au-198 will remain after 10.76 days?
Which type of radiation has no mass and no charge?
Which type of radiation has the greatest penetrating power? Why?
What is the radioactive isotope carbon-14 used for?
How old are the remains of a Neanderthal if the amount of C-14 remaining from a 400g sample is 6.25 18.75
grams?
A sample of krypton-85 was placed in a lab sometime in the 1960s. If 1/16th of the original sample remains,
what was the exact year the sample was placed in the lab?
What is nuclear fusion?
What is nuclear fission?
How are nuclear fusion and nuclear fission similar?
Acids, Bases, and Salts
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What is something acids, bases, and salts have in common?
Which ion do Arrhenius acids release in solution?
Which ion do Arrhenius bases release in solution?
What is the alternate definition of an acid?
What is the alternate definition of a base?
What is the chemical formula for ammonia? Is it an acid or a base?
Write and balance the chemical equation for the neutralization reaction between carbonic acid and magnesium
hydroxide. Name the salt that is produced in this reaction.
Write and balance the chemical equation for the neutralization reaction between perchloric acid and sodium
hydroxide. Name the salt that is produced in this reaction.
What is molarity? What is the symbol for molarity?
What is the molarity of 3 liters of a solution containing 2 moles of NaOH?
What is the molarity of 3 liters of a solution containing 2 moles of Ca(OH)2?
What is the volume of a 2M solution of HBr that is required to neutralize 10 milliliters of a 5M NaOH solution?
What is the molarity of a solution of hydroiodic acid if 85mL of 10M calcium hydroxide are needed to neutralize
50mL of the acid?
For the following, state whether a chemical reaction will occur. If so, write and balance the chemical equation.
a. Sn and HCl
c. Ca and H2SO4
b. Au and HCl
d. Pb and HNO3
A strong acid spill changes the pH levels of the soil in a field 1000-fold. If the original pH of the soil in the field
was 7, what is the new pH of the soil?
A lake affected by acid rain has a pH of 4.5. A base is added to the lake to neutralize some of the acid. Enough
base is added to change the pH of the lake a hundred-fold. What is the new pH of the lake?
Compare the concentrations of H+ and OH- in a neutral solution.
Compare the concentrations of H+ and OH- in an acidic solution.
Compare the concentrations of H+ and OH- in a basic solution.
What three indicators could be used to differentiate between solutions of pH 3 and 6?
Redox
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What is the oxidation state of phosphorus in Na3PO4?
What is the oxidation state of sodium in a sample of Na(s)?
What is the oxidation state of O in O2?
Is an element oxidized or reduced when it loses electrons?
Is an element oxidized or reduced when it gains electrons?
Given the following reaction: H2 + F2 → 2 HF
a. Which species is oxidized?
b. Which species is reduced?
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In the reaction above, electrons are transferred from _____ to _____.
Write the balanced half-reaction for the oxidation reaction.
Write the balanced half-reaction for the reduction reaction.
If 4 moles of electrons are gained by fluorine, how many moles of electrons must be lost by hydrogen?
Electrochemistry
1. What are the three types of compounds (electrolytes) that will conduct electricity in the liquid, molten, or
aqueous phases?
2. What type of element will conduct electricity in the molten phase and as solids?
3. At which electrode does oxidation always occur?
4. At which electrode does reduction always occur?
5. In which direction do electrons flow (from which electrode to which electrode)?
6. Which electrode always gains mass?
7. Which electrode always loses mass?
8. What is another name for a voltaic cell?
9. What is the purpose of the salt bridge in a voltaic cell?
10. In a voltaic cell, chemical energy is converted into what type of energy?
11. A voltaic cell involved a (spontaneous, nonspontaneous) redox reaction that (releases, requires) energy.
12. In a voltaic cell, the metal listed higher on Table J is the one that (loses, gains) electrons and is (oxidized,
reduced).
13. In an electrochemical cell, the metal listed higher on Table J is the one that (loses, gains) electrons and is
(oxidized, reduced).
14. What is electrolysis? Is it spontaneous or nonspontaneous? Does it release or require energy?
15. What is electroplating? Is it spontaneous or nonspontaneous? Does it release or require energy?
Organic Chemistry
1. Refer to notes/blue packet/quiz to review naming of organic compounds.
2. Identify the following type of organic reaction occurring for each of the following:
a. nC2H2 → (C2H2)n
b. C4H10 + Cl2 → C4H9Cl + HCl
c. C6H12O6 → 2C2H5OH + 2CO2
d. C5H10 + H2 → C5H12
e. C2H4 + I2 → C2H4I2
f. C2H4 + 3 O2  2 H2O + 2 CO2
g. CH3COOH + CH3OH  CH3COOCH3 + H2O
3. Write the word equation for a saponification reaction.
4. What are the products of complete combustion?
5. What are the products of incomplete combustion?
6. What are three natural polymers?
7. What are three synthetic polymers?
Miscellaneous
1. Which measurement contains a total of three significant figures? (0.010g, 0.01g, 0.0100g, 0.01000g)
2. Balance the following chemical reactions and identify the type(s) of reaction they are.
a. N2 + O2 → N2O5
b. Al + CuSO4 → Al2(SO4)3 + Cu
c. NaOH + H3PO4 → Na3PO4 + H2O
d. ZnBr2(aq) + AgNO3(aq) → Zn(NO3)2(aq) + AgBr(s)
e. Al(s) + CuCl2(aq) → AlCl3(aq) + Cu(s)
f. 2Ag2O(s) → 4Ag(s) + O2(g)