Chemistry Review for the Spring Final Exam
1. An empty graduated cylinder has a mass of 82.90 grams. A solution is poured into the graduated cylinder
and the cylinder is then reweighed, and found to have a mass of 93.31 grams. The volume of liquid, according
to the graduated cylinder, was 11.0 mL.
a. Determine the density of the solution.
b. Is it likely that this solution consisted of a salt dissolved in water? Why or why not?
c. Out of the beaker, buret, erlenmeyer flask, and pipet, which two of these would be more precise than the
graduated cylinder, and which two would be less precise?
2. The substances lead, ethanol, magnesium chloride, nitrogen, saltwater, water, and hydrogen have the
following densities (though not in order) at 20. Celsius and 1 atm. All values are given in g/mL.
0.000090,
0.0012 ,
0.79,
1.0,
1.1,
2.3,
11
a. Which substance could have which density? Try to do this without looking up any numbers!
b. If you changed the temperature to 50 Celsius, which two substances would change their densities by the
largest percent? Would their densities increase or decrease?
c. If you changed the pressure to 2 atm, which two substances would change their densities by the largest
percent? Would their densities increase or decrease?
3a. Rank these from largest to smallest:
7 micrograms,
70 kg,
7000 grams,
7 nanograms,
700 mg,
7 grams
3b. Convert a speed of 35 feet per hour to millimeters per second. 1 inch = 2.54 cm.
4. a. Convert -31˚C to Kelvin.
b. Convert 334 Kelvin to Celsius.
c. What is wrong with this temperature: -424˚C?
d. What are the conditions at STP? (What T and P? Give units in Celsius, Kelvin, atm, and mmHg)
5. Name these substances:
PbSO4,
HBr,
Cu2S,
K3PO4,
Mg3N2,
HNO2,
MgO,
MgO2
H3PO4,
6. Write formulas for these:
Tin II oxide,
sulfuric acid,
aluminum nitrate,
sulfurous acid,
aluminum sulfate,
nitrogen,
hydrocyanic acid,
heptane,
7.a. How many protons, neutrons, and electrons are in Na, Na+1, P, and P-3?
Assume that these are the most common isotopes.
b. How many protons, neutrons, and electrons are in
39
K+1 ,
15
N-3 and
235
U+6?
c. Which, if any, of the symbols in part b show the most common isotope of the element?
heptene
d. Name three elements with the same number of valence electrons as sulfur.
e. Give the symbol for four ions with the same number of electrons as argon.
f. Give the symbol for four atoms or ions with the same number of electrons as nitride ion.
8. Use this data to calculate the atomic mass of magnesium:
Isotope
Natural Abundance Mass(amu)
24
Mg
78.99%
23.98504
25
Mg
10.00%
24.98584
26
Mg
11.01%
25.98259
9. (For each question in number 9, circle a pair of things)
Which of these proton/electron/neutron counts could represent the same element?
12 p,12 e, 13 n,
11 p, 11e, 13 n
11p, 11e, 12 n
13 p, 12e, 12 n
Which of these proton/electron/neutron counts could represent a particle with the same charge?
12 p, 10 e, 13 n,
11 p, 12e, 13 n
11p, 11e, 12 n
13p, 13e, 11n
Which of these are in the same period?
C
S
F
I
Which of these are in the same family?
C
S
F
I
Kr
Ba
Xe
Ba+2
Kr
Ba
Xe
Which of these have the same number of electrons?
Which of these have the same number of valence electrons?
C
Which of these are the same thing?
a beta particle
gamma radiation
an electron
Which of these are the same thing?
Cu2SO3
copper (II) sulfate
Copper (I) sulfite
a neutron
an alpha particle
CuSO3
Cu(SO4)2
Cu2SO4
10. Make the following conversions:
a.
2.00 x 1023 fluorine molecules into grams.
b.
2.00 x 1023 fluorine molecules into atoms.
c.
2.00 x 1023 fluorine molecules into moles
d.
45.2 grams of water into molecules
e.
0.011 moles of water into grams
f.
1.0 x 1022 molecules of methane into grams
g.
1.0 x 1022 molecules of methane into atoms
11. Determine the products for each reaction (include subscripts) and balance it.
Then write a balanced net ionic equation for any starred reactions.
a.
C6H14 (l)+ O2(g) ----->
*b.
NaOH(aq) + H2SO4(aq) ------->
*c.
AgNO3(aq) + Na2S(aq) ------->
*d.
Zn(s)
+
FeBr3(aq) ----->
e.
O2(g)
+
Na(s) ----->
*f.
Na3PO4(aq) + CuSO4(aq)------->
*g.
HNO3 (aq)+ K2CO3(s)------->
h.
Al(s)
+
S(s) ------>
*i.
Al(s) + HNO3(aq)------->
*j.
Al(s) + Cu(NO3)2(aq)------->
k.
C(s) + O2(g)
*l.
m.
*n.
------->
Br2 (l) + NaI(aq) ------>
C5H11OH(l) +
O2(g)----->
H2O(l) + K(s) ------->
o.
H2(g) + O2(g) ------->
p.
Br2 (l)
+
Al(s) ----->
q.
O2 (g)
+
Al(s) ----->
12. a. Which of the above reactions are neutralization reactions?
b. Which of the above reactions are precipitation reactions?
c. Which of the above reactions are combustion reactions?
d. Which of the reactions in the above problem are NOT redox reactions?
e. For reactions d,e,l,p,q :
- identify the substance oxidized by the reaction
- identify the substance reduced by the reaction
-determine the total number of electrons transferred in the balanced equation
13. In class, we looked at the flame/splint tests for hydrogen gas, oxygen gas, and carbon dioxide gas.
Explain what you would observe in a positive flame test for each of these three gases.
14. a. What is the empirical formula for a compound with the molecular formula C6H12O9?______________
b. If a compound has an empirical formula of CH2 and a molecular weight between 50 and 60 amu, what is the
molecular formula of the compound?
15. A compound is 40.7% carbon, 54.2% oxygen, and 5.1% hydrogen.
a. What is the empirical formula?
b. What is the molecular formula, if the molecular weight is between 200 and 250 amu?
16. a. What is the percent composition (by mass) of sodium in sodium oxide?
b. If 40.0 grams of sodium oxide are broken down chemically, how many grams of oxygen will be released?
c. If 50.0 grams of sodium gain oxygen due to reaction with air, what will be the final mass of the sodium
oxide?
17. In lab, 1.24 grams of chromium were burned in a crucible.
After burning, the final mass of solid in the crucible was _____ grams.
a. Which number would make sense for the final mass: 2.00 g, or 0.48 grams?
b. Based on the mass you chose, find the percent composition of oxygen in the compound that formed.
c. Find the empirical formula of the compound that formed.
18.
Al(s) + Cl2(g) ------>
a. Complete the reaction and balance it.
b. Identify each substance in the reaction as a covalent compound, ionic compound, nonmetal, or metal.
c. How many aluminum atoms are needed to react with 1.0 x 1023 chlorine molecules?
d. How many grams of aluminum are needed to react with 1.0 x 1023 chlorine molecules?
e. How many moles of product can form if 1.0 x 1023 chlorine molecules react?
18f. If 2.30 grams of aluminum are allowed to react with 6.20 grams of chlorine, how many grams of product
should form?
g. If only 7.57 grams of product form in (f), what was the % yield?
h. What was the limiting reactant in part (f)?
i. If the amounts in (f) react, which of these would be a reasonable number for the mass of reactant leftover?
a. 0.73 g Al
b. 3.87 g Al
c. 7.77 g chlorine
d. 4.63 g chlorine
19.a. What is the normal boiling point of water, in Celsius?______________
b. Water has a specific heat of 1.00 ______________ (fill in the units!)
c. How much energy, in calories, would be needed to heat 200.0 grams of water from 16.0˚C up to its normal
boiling point?
d. A piece of metal with a mass of 24.51 grams requires 465 Joules of energy to increase the temperature from
22.0˚C to 53.9˚C. Determine the specific heat of the metal, and include units.
Aluminum has a specific heat of 0.21 cal/g˚C.
e. A piece of aluminum required 350 calories in order to increase its temperature from 130.˚C to 140.˚C. Find
the mass of the aluminum.
f. If 700. calories are provided to a piece of aluminum with a mass of 500. grams, what temperature will the
aluminum reach, if it starts out at 20.0˚C?
20. Which substance would increase its temperature more, for a given input of heat energy:
a. A substance with a high mass and a high specific heat.
b. A substance with a low mass and low specific heat.
c. A substance with a high mass and a low specific heat.
d. A substance with a low mass and a high specific heat.
21. a. List all of the possible phase changes that a substance can undergo.
b. Which phase changes are endothermic?
c. Which phase changes are exothermic?
21d. Classify each process as exothermic or endothermic:
Combustion of gasoline
photosynthesis
a reaction with a ΔH of -22 kJ/mole
breaking a chemical bond
cellular respiration
forming a chemical bond
a reaction with a ΔH of 146 kJ/mole
reaction of potassium with chlorine
oxygen reacts with magnesium
an electron “jumps” from n = 6 to n = 1
an electron “jumps” from n = 2 to n = 5
Substance
C2H2(g)
CO2(g)
H2O(g)
ΔHformation(kJ/mole)
226.7
-393.5
-241.8
Substance
H2O(l)
H2S(g)
SO2(g)
+ SO2(g)
ΔHformation(kJ/mole)
-285.8
-20.17
-296.9
22. a. Find the ΔHrxn for this equation:
2 H2S(g)
-------> 3 S(s) + 2 H2O(g)
b. Find the ΔHrxn for this equation:
3 S(s) + 2 H2O(g) -------> 2 H2S(g)
+ SO2(g)
(you shouldn’t need your calculator for (b)!)
c. Classify reactions (a) and (b) as exo- or endo-thermic, and write the heat term into each equation.
d. Sketch an energy diagram for reactions (a) and (b). Label the axes, the ΔHrxn, and the activation energy on
each.
e. For each graph, redraw the curve if a catalyst were added.
f. Besides adding a catalyst, name three things to do to increase a reaction’s rate, and explain briefly why each
thing increases the rate.
23. a. Write a reaction for the combustion of acetylene (ethyne), C2H2.
Balance with whole number coefficients.
b. Use bond enthalpies (see the chart on WS 11.1) to estimate ΔHrxn for the reaction in (a)
c. Use heats of formation to calculate ΔHrxn for the reaction in (a)
d. Ethene and Ethane are also combustible. If you compare the combustion of ethane, ethene, and ethyne,
which would you expect to have the highest activation energy, and which would you expect to have the lowest
activation energy?
e. Based on your answer to c, if 94.4 grams of acetylene combust, how much heat will be produced?
24. Given the following:
3 O2(g) + C2H5OH(l) -------> 2 CO2(g) + 3 H2O(g)
ΔHrxn = -1234.7 kJ
6 CO2(g) + 6 H2O(l)
-------> 6 O2(g) + C6H12O6(s) ΔHrxn = 2802 kJ
H2O(l)
-------> H2O(g)
ΔHrxn = 44.0 kJ
Calculate ΔHrxn for this reaction. C6H12O6(s)
-------> 2 CO2(g) + 2 C2H5OH(l)
25. Given: 2 C8H18 + 25 O2 -------> 16 CO2 + 18 H2O + 10242 kJ
a. What is the ΔH for the above reaction?
b. If 15.0 grams of octane burn, how much energy will be produced?
c. If the reaction consumes 17.0 liters of oxygen gas (when measured at a pressure of 750. mmHg and a
temperature of 25˚C), how much energy will be produced?
d. What mass of oxygen gas is required to produce 8500 kJ?
26. a. Write out the balanced chemical reaction for photosynthesis.
b. ΔH for this reaction is +2800 kJ/mole. Is this reaction exo- or endothermic? _____
c. Write the heat term into the equation on the correct side.
d. This reaction requires an energy source. Where does the energy come from?
26. e. Rewrite your photosynthesis reaction, but reverse the reactions and products.
f. What is the ΔH for this reaction?_______
g. Is this reaction exo- or endothermic? _____
h. Write the heat term into the equation on the correct side.
i. When this reaction occurs in your body it is called _____________________________.
27. A sample of chlorine gas has a volume of 50.0 liters when the temperature is 25.0˚C and the pressure is
10.0 atm.
a. How many moles of chlorine gas are in this sample? R = 0.0821 l-atm/mol-K
b. How many grams of chlorine are in this sample?
c. What volume will 47.8 grams of carbon dioxide occupy at -22˚C and 842 mmHg?
28. a. A sample of oxygen occupies 2.00 liters when the temperature is 22.0˚C. What will be the new volume
of the oxygen gas if the temperature changes to 44.0˚C, assuming that the pressure remains constant?
b. 1.4 L of helium are at a pressure of 1.00 atm and a temperature of 30.0˚C. What will be the new pressure if
the helium is compressed to 675 mL and the temperature is increased to 50.0˚C?
29. If you have two 4.00 liter flasks, and each contains a gas at the same temperature and pressure,
(the gases are different substances), which things are necessarily equal in the containers?
a. The number of moles of gas.
b. The number of atoms.
c. The number of molecules.
d. The mass of gas.
e. The density.
f. The average kinetic energy.
g. The average molecular speed.
30. a. Sketch a graph of gas pressure vs. temperature
(if moles and volume are held constant).
Is this an inverse or a direct relationship?
b. Same question as (a), except pressure vs volume.
(if moles and temp are constant)
c. Same question, except volume vs. Temperature
(if moles and pressure are constant)
d. Gases are the most dense when the temperature is _______ and the pressure is ______.
31. A sample of gas has a volume of 10.0 liters when at STP.
a. What are the temperature and pressure of the gas? Include units.
b. What will be the new volume if the pressure is doubled (temp held constant)?
c. What will be the new pressure if the volume is changed to 2.50 liters (temp held constant)?
d. What will be the new volume if the temperature is changed to 546 Kelvin? (pressure constant)
e. What will happen to the density if the pressure is cut to one third its STP value? (temp held constant)
f. Name two gases (choose elements or compounds) that are less dense than nitrogen and two gases that are
more dense than nitrogen. (Assume that the gases are at the same T and P as nitrogen)
32. Potassium nitrate, or “saltpeter” is used in many types of fireworks.
It decomposes according to the following reaction: 4 KNO3(s) -------> 2 K2O(s) +
2 N2 (g) + 5 O2(g)
a. If 10.0 grams of potassium nitrate decompose, how many grams of oxygen gas will be produced?
4 KNO3(s) -------> 2 K2O(s) +
2 N2 (g) + 5 O2(g)
b. What will be the volume of oxygen gas produced in (a) if the temperature is 500.˚C and the pressure is 1.20
atm?
c. If 5.00 grams of potassium nitrate decompose into an evacuated 2.00 liter container, what would be the total
gas pressure in the container, if it reaches a temperature of 350˚C?
33.
2 H2(g) + O2(g) --------> 2 H2O(g)
If 30.0 grams of oxygen gas react, how many liters of water vapor will be produced, if measured at 732 mmHg
and 125 ˚C?
34. a. Determine the wavelength (in meters and in nm) and the photon energy of light with a frequency of
1.55 x 1015 Hz.
b. Determine the energy and frequency of light with a wavelength of 444 nm.
c. Put these types of electronmagnetic radiation from highest to lowest energy: red, green, infrared, gamma,
ultraviolet, microwave, radio.
d. Of the types in (c), which has the highest frequency?
e. Of the types in (c), which has the longest wavelength?
f. Which type of EM radiation is most commonly associated with skin cancer?
g. Which these has higher energy:
EM radiation with a wavelength of 40 nm
or
EM radiation with a wavelength of 40000 nm
blue light
or
green light
light with a frequency of 1 x 1015 Hz
or
light with a frequency of 3 x 1015 Hz
35. For each pair of things, indicate whether they are attracted to each other, repelled by each other, or neither.
protons and electrons
electrons and neutrons
electrons and other electrons
the nucleus and electrons.
Lone pairs and bond pairs in a molecule
bond pairs and other bond pairs in a molecule
electrons in a bond, and the nuclei of the atoms on either side of the bond
a metal cation and nonmetal anion in an ionic compound
36. If one electron leaves an atom, what charge of ion will form?______
36.5. An electron requires energy to leave the atom. This is mainly because _____________.
a. the electron and nucleus both have mass, so there is a gravitational attraction
b. the electron and nucleus both have mass, so there is a gravitational repulsion
c. the electrons are repelled by the other electrons in the atom
d. the electrons are attracted to the other electrons in the atom
e. the electrons are attracted to the nucleus in the atom
f. the electrons are repelled by the nucleus in the atom.
37. How does the nucleus compare to the rest of the atom in terms of mass?
How does the nucleus compare to the rest of the atom in terms of size (volume)?
How does the nucleus of an atom compare to other substances in terms of density?
38. a. Write the electron configurations (1s22s2.....) for Al, P, Ba, Pb, Re, and Am.
b. Use the electron configurations to determine how many valence electrons each element has (underline the
valence electrons)
c. Write the electron configuration for aluminum ion and phosphide ion.
d. Out of all the orbitals in this problem, which has the lowest potential energy, and why?
e. Which of these best describes an orbital?
a cloud within the nucleus where an electron is likely to exist.
a circular path an electron makes around nucleus
an elliptical path an electron around a nucleus
a very specific location of an electron in an atom
a rough volume where an atom’s electron is likely to exist
39. Which of these quantities is NOT conserved:
40a.
a. mass
b. volume
c. charge
d. energy
Rank Na, Cl, F, and Ba according to electronegativity.
b. List the formulas of any ionic compounds that could form between the four elements in (a).
c. Which pair(s) of elements could bond covalently together?
d. Give an example of a compound in (b) or (c) in which chlorine was sharing electrons.
e. Give an examples of a compound in (b) or (c) in which chlorine gained or lost electrons (which one?) to
form the compound.
41. Out of metals and nonmetals:
a. Which are good conductors of heat and electricity?
b. Which are non-flexible when solid?
c. Which are almost always solids at room temperature?
d. Which type contains all the diatomic elements?
e. Which have low electronegativities?
f. Which tend to form positive ions when they react?
g. Which tend to gain or share electrons when they react?
h. What determines whether the above elements (in g) gain electrons or share electrons? Explain.
42. For each compound or ion: NH3 , H2O , CO2 , PF3 , NO2-1, PO4-3, CO3-2
a) Draw the Lewis dot structure
b) Determine the electron geometry, molecular geometry, and bond angle
c) Sketch the molecule, showing the correct molecular geometry.
d) Classify the first four molecules as polar or nonpolar. If polar, draw the net polarity arrow.
(assume that each has a large enough ΔEN to be polar)
e. What type of bond: ionic or covalent, is found in each substance?
43. Out of the compounds KCl, CaSO4, H2CO3, and MgF2,
a. Which one(s) contain only covalent bonds?
b. Which one(s) contain only ionic bonds?
c. Which one(s) contain both ionic and covalent bonds?
d. Draw a picture/structure for the first three substances, and label any ionic or covalent bonds.
44. A solution was made by dissolving 48.0 grams of sodium chloride into 152 grams of water. The total
solution volume after mixing came to 169 mL.
a. What is the density of this solution?
b. What is the molarity of this solution?
45.a. How many grams of CuSOo are needed to make 500.0 mL of 0.800 Molar CuSOo solution?
b. If you
take 40.0 mL of the above solution and then add water until the total volume is 2.00liters, what
be the new molarity of the solution?
will
a. Memorize functional groups alkane, alkene, alkyne, aromatic, alcohol, acid
b. Of the above functional groups, which are polar?
46.
q -ù
c.
V/hat is the formula of this compound?
d. Name the following compounds:
,(::t
C
H
O
ì4
N
¡
c- c_.c- c/ol*
c
(./
.t
)o'
\\
I
c- c-cc- c 4
l
I
c c L
I
c
e. Draw the structure of the following compounds. Show polarity arrows on polar bonds of polar
butanoic
ethanol,
acid
1,4
dichlorobenzene
propyne,
3,4,5 trimethyl
2-heptene
ethanaldehyde (CrHrO),
substances
ethylamine
2-heptanol
f. The substances ethanol, propyne, ethanaldehyde, and 2-heptanol have boiling points of -23˚C, 20˚C, 78˚C,
159˚C, (though not in order). Which substance has which boiling point?
g. Consider the following alcohols: 2-heptanol, 2-hexanol, 2-pentanol, 2-butanol, and 2-propanol.
Which of these would you expect to have the highest boiling point, and which would have the lowest?
Which of these would you expect to have the highest solubility into water, and which would have the lowest?
One of these compounds is “miscible” with water. Which one?
47. a. What is the pH of a 0.0020 M HCl solution?
b. What is the pH of a 0.0020 M KOH solution?
c. What is the pH of a 0.0020 M Ba(OH)2 solution?
d. What is the pH of a 0.00020 M MgCl2 solution?
47e. Of the above four solutions, which was the most acidic and which was the most basic?
f. What molarity of HCl would be necessary to have a solution with a pH of 3.21?
g. What molarity of LiOH would be necessary to have a solution with a pH of 11.48?
h. What is the concentration of hydrogen ion in a solution with a pH of 12.3?
i. What is the hydroxide concentration in a solution with a pH of 14.22?
j. If 25.0 mL of 0.12 M KOH are required to neutralize 40.0 mL of H2SO4, what was the concentration of the
sulfuric acid?
k. If 0.0033 grams of barium hydroxide are dissolved per 100. mL of aqueous solution, calculate the pH.
l. Calculate the pH of a solution containing 0.017 grams of hydrochloric acid per 2.00 liters of solution.
47m. If you have two solutions, one with a pH of 2.57, and one with a pH of 5.57, which solution contains a
higher concentration of hydrogen ions? How many times higher is the [H+1] in this solution?
48. Identify each substance as acidic, basic, or neutral:
LiOH
C3H7OH
BaCO3
H3PO4
ammonia
Ca(OH)2
soda (sprite, etc.)
HNO3
CH3CH2COOH
vinegar
NH3
HC4H9O2
drano (drain cleaner)
lemon juice
H2O
K2CO3
baking soda
49. a. Write an equation for the alpha decay of U-238.
b. Write an equation for the beta decay of Carbon-14.
c. Fill in the blank:
235
U
+ 1n ------>
137
Ba
+ _________ + 3 1n
d. Was the reaction above fission or fusion?
e. Carbon-14 has a half-life of 5730 years. If you start with a 50.0 mg sample of C-14, how much of it will
remain as C-14 after 15000 years have passed?
49f. If a scroll contains 8.2% of its orginal C-14 content, how old is the scroll?
50. Out of
H2, Cl2, CO, CO2, C6H12O6, NO, NO2, SO3, C7H16, O2, O3, N2, freon (CF2Cl2), and NH3
a. Which substance is harmful to inhale, because it inhibits your hemoglobin’s ability to transport oxygen?
b. Which gas is not toxic (except in high amounts) but is a greenhouse gas?
c. Which gas is called ozone?
d. Which is highly flammable, and is a gas at room temperature?
e. Which substance is a component of gasoline?
f. Which substance is a sugar?
g. Which two gases are free radicals, and what does this mean?
h. Which gas is a reactant in all combustion reactions?
i. Which substance dissolves in water to create a basic solution? What is the substance called?
j. Which two gases come from car pollution and lead to acid rain? What acid forms?
k. Which gas comes from coal burning, and leads to acid rain? What acid forms?
l. Which substance is the most abundant in our atmosphere?
m. Which is the second most abundant substance in our atmosphere?
n. Which substance contributes to ozone depletion?
o. What type of electromagnetic radiation does ozone shield us from?