SCH3U - EXAM REVIEW – UNIT 1
1. Complete the table below.
2. What is the difference between ionization energy and electron affinity?
3. Why does ionization energy increase from left to right in a period on the periodic table? 4. Examine the following 1st, 2nd, and 3rd ionization energies and state which element is most
likely a noble gas.
5. The electronegativity of magnesium, Mg, is 1.2. Would you expect aluminum's electronegativity to be higher or lower?
6. For a science fair project, a student wants to design a simple device for removing certain gases from polluted air. He knows that polar molecules dissolve well in water, so he bubbles polluted air through a jug of water to remove unwanted gases. For his project, the student uses air containing the following gases:
List the gases that will dissolve by writing down their corresponding numbers.
7. List three empirical properties of the molecular elements (i.e., nonmetals). 8. A student records the following evidence in a lab book.
Which of the substances in the table above is most likely an ionic compound? Explain your answer. 9. Briefly describe how polar covalent bonds occur.
Element name Element symbol Atomic number Group number Family name Period number Metal or nonmetal fluorine Ba
noble gas 3
1st (eV) 2nd (eV) 3rd (eV)
Element X 5.139 47.286 71.64
Element Y 7.646 15.035 80.143
Element Z 21.564 40.962 63.45
1. N2(g) 5. CH4(g)
2. O2(g) 6. OCl2(g)
3. HF(g) 7. C3H8(g)
4. NH3(g) 8. CH3OCH3(g)
Unknown substance Pure state Solubility in water Solution conductivity
I solid high low
II solid low low
III solid high none
C2H5OH(l) + O2(g) →
UNIT 1 EXAM REVIEW- Answer Section
1.
2. Ionization energy is the energy required to remove an electron from an atom. Electron affinity is the energy released when an atom accepts an electron.
3. Ionization energy increases because atomic radius decreases. This happens because the nuclear charge increases, but the number of energy levels does not. Therefore, the nucleus has a stronger hold on the electrons as the nuclear charge increases.
4. element Z 5. higher 6. 3, 4, 6, and 8
7. They may be solids, liquids, or gases at SATP (a great variation in melting and boiling points), are brittle in solid form (not flexible, malleable, ductile, or bendable), and are nonlustrous (not shiny).
8. Substance IV is most likely to be an ionic compound because its high solution conductivity indicates that ions are present in the solution.
9. When two nonmetals react with each other, they try to form stable octets. To do this, they share electrons. If one atom is much more electronegative than the other, they will not share the electrons equally. Thus, one end of the bond is more negative than the other and the bond is polar.
10. Atoms are more stable when they have eight valence electrons. Nonmetals will try to gain electrons to form a stable octet and metals will try to give away electrons to form a stable octet. Thus, metals give electrons to nonmetals. Subsequently, the two oppositely charged ions are attracted to one another.
11. Sodium forms an ion with a 1+ charge and oxygen forms an ion with a 2– charge. This means that the smallest unit with a zero charge would require two sodium ions and one oxide ion.
12. H2SO4(aq) + 2NaOH(aq) 2HOH(l) + Na2SO4(aq)
13. 2Fe(s) + 3Cu(NO3)2(aq) 3Cu(s) + 2Fe(NO3)3(aq)
14. 2AlCl3(aq) + 3Na2CO3(aq) Al2(CO3)3(s) + 6NaCl(aq)
15. C2H5OH(l) + 3O2(g) 2CO2(g) + 3H2O(g)
16. Between the one sulfur atom and two oxygen atoms, there are 18 valence electrons. The only way for three atoms to attain stable octets is to arrange themselves as shown in the following diagram. Element name Element symbol Atomic number Group number Family name Period number Metal or nonmetal
fluorine F 9 17 halogens 2 nonmetal
barium Ba 56 2 alkali earth
metals
6 metal
SCH3U - EXAM REVIEW - UNIT 2
1. Zinc oxide can be used for treating certain skin conditions. Determine the molar mass of ZnO. 2. Calculate the number of fluoride ions present in 0.669 mol of barium fluoride, BaF2.
3. Define the term "limiting reagent".
4. Balance the following equation by inspection: CoCl2 + NaOH NaCl + Co(OH)2 5. Translate the following into a balanced chemical equation:
Four moles of ammonia gas reacts with 5 mol of oxygen gas and produces 4 mol of nitrogen dioxide gas and 6 mol of water in the gaseous state.
6. State the mole ratio between the reactants in the following balanced equation: 4NaOH + 2F2 4NaF + 2H2O + O2
7. If 109.6 g of sodium hydroxide was the amount obtained in a reaction for which the theoretical yield was 170.5 g, determine the percentage yield.
8. Natural neon contains three isotopes: Ne-20, Ne-21, and Ne-22. In a sample, 90.92% of the atoms are Ne-20, 0.26% of the atoms are Ne-21, and 8.82% of the atoms are Ne-22. Using a sample population of 10 000 neon atoms, calculate the average atomic mass of neon.
9. Calculate the mass found in 1.27 mol of sodium phosphate.
10. Titanium dioxide, TiO2, can be used as an abrasive in toothpaste. Calculate the percentage of titanium, by mass, in titanium dioxide.
11. Glucose contains 39.95% C, 6.71% H, and 53.34% O, by mass. If the molar mass of glucose was found experimentally to have a molar mass of 180.0 g/mol, calculate its molecular formula. 12. Consider the following combustion reaction: C3H8 + 5O2 3CO2 + 4H2O
Determine the mass of carbon dioxide that will be formed when 131.0 g of propane, C3H8, is reacted with excess oxygen.
13. Consider the following balanced equation: Mg(OH)2 + 2HCl MgCl2 + 2H2O
Determine the mass of magnesium chloride produced when 5.91 g of Mg(OH)2 is combined with 9.98 g of HCl. 14. Sodium chloride is produced when sodium metal combines with chlorine gas as shown in the
following balanced equation: 2 Na + Cl2 2 NaCl
In an experiment, 36.9 g of sodium chloride is produced when 15.9 g of Na and 27.4 g of chlorine are combined. Determine the percentage yield of the product.
EXAM REVIEW UNIT 2 Answer Section
1.
2.
There are 4.03 X 1023 formula units in 0.669 mol of BaF
2. There are two F– ions in each formula unit. Therefore,
there are 8.06 X 1023 F– ions present in this sample.
3. The limiting reagent is the first reactant in a chemical reaction to be completely consumed before the remaining reactant(s) is/are.
4. CoCl2 + 2NaOH 2NaCl + Co(OH)2
6. NaOH:F2 = 2:1
7.
8. Ne-20: 90.92% or 9 092 atoms Ne-21: 0.26% or 26 atoms
Ne-22: 8.82% or 882 atoms
The average atomic mass of neon is 20.18 u. 9. n = 1.27 mol
M = 164.0 g/mol
The mass of 1.27 mol of Na3PO4 is 208 g.
10. mTi = 47.88 u X 1 atom = 47.88 u mO = 16.00 u X 2 atoms = 32.00 u
mtotal = 79.90 u
The percentage composition of titanium in TiO2 is 59.94%. 11.
The molar ratio for C:H:O is 3.33:6.64:3.33. Dividing by 3.33 to obtain the lowest ratio, we obtain the molar ratio of 1:2:1. The empirical formula of the compound is CH2O.
The molecular formula of the compound is C6H12O6. 12.
The mass of carbon dioxide that will be produced is 393.0 g.
13. We can determine the number of moles of HCl needed to react completely with 5.91 g of magnesium hydroxide.
More HCl is available than is required, therefore, HCl is in excess. The magnesium hydroxide is the limiting reagent.
The mass of magnesium chloride produced is 9.62 g. mole ratio: C3H8:CO2 = 1:3
mole ratio: Mg(OH)2:HCl = 1:2
14. We can determine the number of moles of chlorine needed to react completely with 15.9 g of Na.
More chlorine is available than is required, therefore, chlorine is in excess. The sodium is the limiting reagent.
The theoretical yield of the NaCl is 40.4 g.
The percentage yield is 91.3%.
mole ratio: Na:Cl2 = 2:1
SCH3U - EXAM REVIEW- UNIT 3
1. Using the solubility table below, state whether the following ionic compounds are soluble or insoluble in water.
2. A sample of well water is known to contain a high concentration of iron. What solution could you use to test the water to get a positive precipitate test for the dissolved iron?
3. Consider the following reaction: Barium chloride solution is mixed with potassium sulphate solution to produce a solid precipitate barium sulphate and a solution of potassium chloride. For this reaction, write
(a) a balanced chemical equation (b) a total ionic equation
(c) a net ionic equation
4. Write the ionic equation to represent the dissociation of calcium hydroxide. 5. How does dilution affect the pH of
(a) acidic solutions? (b) basic solutions?
6. D5W is an intravenous solution used as a fluid and nutrient replenisher for patients. As a hospital pharmacist you need to make 750 mL of this solution with a concentration of 0.30 mol/L. What mass of glucose, C6H12O6, will you need to dissolve in water?
7. T.S.P. is an all purpose cleaner that can be used to clean driveways. What volume of solution would you get if you dissolved 150.0 g of sodium phosphate with water to produce a 0.23 mol/L solution?
8. A "sports drink" contains 50 mg of sodium ions and 55 mg of potassium ions per 400 mL serving. Calculate the concentration of the sodium and potassium ions in ppm.
9. How much water must be added to 600 mL of a 1.5 mol/L CaCl2 solution to make the concentration of the resulting solution 1.0 mol/L?
10. Some commercial bleach solutions contain 5.25% W/V sodium hypochlorite. Calculate the sodium hypochlorite concentration in mol/L.
11. A student mixed 100.0 mL of a 0.100 mol/L solution of barium chloride with 100.0 mL of a 0.100 mol/L solution of iron(III) sulphate. The barium sulphate precipitate was filtered, dried, and was measured to have a mass of 2.0 g. Calculate the % yield of the barium sulphate.
12. A swimming pool has a pH of 7.5. Calculate the hydrogen ion concentration in the pool. 13. A teaspoon of milk of magnesia contains 12.0 mg of magnesium hydroxide. What volume of
0.01 mol/L HCl in a person's stomach would be neutralized by this teaspoon of antacid?
EXAM REVIEW UNIT 3 Answer Section
1.
Compound Soluble or insoluble
(a) PbI2
(b) KClO3
(c) CaCO3
(d) BaSO4
Compound Soluble or insoluble
(a) PbI2 Insoluble
(b) KClO3 Soluble
(c) CaCO3 Insoluble
2. A sodium hydroxide solution. (There are several other possibilities that students could choose by using a
solubility rules table.)
3. (a) BaCl2(aq) + K2SO4(aq) → BaSO4(s) + 2KCl(aq)
(b) Ba2+(aq) + 2Cl–(aq) + 2K+(aq) + SO42– (aq) → BaSO4 (s) + 2K+(aq) + 2Cl–(aq) (c) Ba2+(aq) + SO42– (aq)→ BaSO4(s)
4. Ca(OH)2(s)→ Ca2+
(aq) + 2OH–(aq)
5. (a) Diluting acidic solutions decreases the hydrogen ion concentration. This increases the pH and makes these solutions less acidic.
(b) Diluting basic solutions decreases the pH and makes these solutions less basic.
6.
The mass of glucose needed is 40 g.
7.
The volume of the solution will be 4.0 L.
8.
9.
The amount of water that must be added for the dilution is 300 mL.
10.
The sodium hypochlorite concentration is 0.705 mol/L.
11. 3BaCl2(aq) + Fe2(SO4)3(aq) 3BaSO4(s) + 2FeCl3(aq)
The theoretical mass of barium sulphate is 2.3 g.
The % yield of the barium sulphate precipitate was 87%.
12.
The hydrogen ion concentration of the swimming pool is 3.2 X 10–8 mol/L.
13. Mg(OH)2(aq) + 2HCl(aq) MgCl2(aq) + 2H2O(l)
100.0 mL 100.0 mL m
0.100 mol/L 0.100 mol/L
SCH3U - EXAM REVIEW UNIT4
1. Make a list of five ways that the knowledge of gases is used in the proper design and functioning of an automobile.
2. Explain Boyle’s law using the kinetic molecular theory. 3. Explain Charles’s law using the kinetic molecular theory. 4. Solve for the missing variable in the following chart:
5. The total pressure of a gas mixture of He and CO is 12 atm. If there is twice as much CO as He, what is the partial pressure for both gases?
6. Butane from a lighter undergoes combustion in the following manner: 2C4H10 (g) + 13O2 (g) → 8CO2 (g) + 10 H2O (g)
What volume of butane was burned to produce 325 mL of CO2 (g)
7. A balloon filled with helium gas has a volume of 5.80 L measured at 101.325 kPa and is placed into a hyperbaric chamber at a pressure of 1255 mm of Hg. What will the new volume be if the temperature remains constant throughout the process?
8. A gas occupies a volume of 825 mL at a temperature of 25ºC and a pressure of 0.985 atm. What will the new pressure be, if the volume is decreased to 555 mL while the temperature remains constant?
9. Determine the number of moles of neon gas contained in a 5.25-L gas tank at 105 kPa and a temperature of 299 K. If the gas is nitrogen instead of neon, will the answer be the same? Explain your reasoning.
10. What would be the difference in size of a 10.5-L balloon filled with He gas at STP if it is brought in from outside to conditions identical to SATP?
11. A fire extinguisher filled with carbon dioxide has a mass of 3500 g. After releasing all of the CO2, the mass of the extinguisher is 2735 g. What was the pressure reading on the gauge before any CO2 was released, if the volume of the extinguisher is 4.25 L and it is stored at a temperature of 25ºC?
12. Magnesium was added to hydrochloric acid, HCl, and produced 5.25 L of H2 gas at a temperature of 325 K and a pressure of 100 kPa. What mass of Mg was used in this single displacement reaction?
13. Acetylene is burned in the presence of oxygen gas during the welding process according to the following balanced chemical equation: 2C2H2 (g) + 5O2 (g) 2H2O (g) + 4CO2 (g)
If you have 40 L of acetylene at STP, what volume of oxygen gas will you need at STP to completely burn the acetylene?
EXAM REVIEW UNIT4 Answer Section
1. -air bags -hydraulic systems in shocks -air brakes
-combustion of fuel and oxygen in car engine (stoichiometric ratios) -catalytic converter to reduce pollutants
-volume versus pressure ratio for firing pistons
-composition of fuels for better efficiency (higher octane rating)
-any answer that applies to gases (ask student for clarifications if in doubt)
2. Assume that the number of particles in a gas and the temperature of the gas remains constant. As the pressure increases on the gas, the particles will be forced to move in closer to one another, thereby decreasing the total volume that they occupy. As the volume decreases, there will be more collisions with the sides of the container due to the reduction of exposed surface area, but the number of particles is constant. (More particles hitting the same spot on the sides of the wall increases the pressure.)
3. Assume that the pressure and number of molecules of a gas are constant. As the temperature increases, the particles gain more energy, thereby increasing the distance separating the individual gas particles. As the distance increases, so does the volume, because gases always occupy the
P1 P2 V1 V2
entire volume of their containers. As the particles lose kinetic energy (i.e., are cooled), the particles get closer together and reduce the total volume that they occupy. The individual size of the particles do not change and are considered dimensionless points in this theory.
4.
5. Ptotal = PHe + PCO
Since the amount of CO is twice the amount of He the equation can be written as
PCO = 12 – 4 = 8 atm
6.
PROBLEM
7. P1 = 101.325 kPa V1 = 5.80 L
P2 = 1255 mm of Hg V2 = ?
V1 = 825 mL V2 = 555 mL The new pressure is 1.46 atm 9. V = 5.25 L
P = 105 kPa T = 299 K
R = 8.31 kPa L/mol K n = ?
The answer would be the same if the question asked for the number of moles of nitrogen gas. The question assumes ideal gases and Avogadro's theory states that two gases at the same temperature, pressure, and volume would contain the same number of molecules. If you have the same number of molecules, you have the same number of moles; however, the masses will be different.
10.
The difference in size would be 11.6 L – 10.5 L = 1.1 L.
11. mass of full extinguisher = 3500 g mass of empty extinguisher = 2735 g
V = 4.25 L
T = 25ºC + 273 = 298 K R = 8.31 kPa L/mol K P = ?
n = ?
mass of CO2 = 3500 g – 2735 g = 765 g
P1 V1 T1 P2 V2 T2
The pressure reading was 1.01 104 kPa.
12. Mg(s) + 2HCl(aq) MgCl2 (aq) + H2(g)
P = 100 kPa V = 5.25 L
R = 8.31 kPa L/mol K T = 325 K
nH2 = ?
Therefore, 4.72 g of Mg was added to the HCl to form 5.25 L of H2.
SCH3U - EXAM REVIEW UNIT 5
1. List the different groups of compounds that hydrocarbons can be divided into. 2. What does the octane rating of a gasoline indicate?
3. Draw and name three isomers of an alkane containing six carbons. 4. What is the key characteristic that distinguishes alkynes from alkanes?
5. When naming branched alkenes or alkynes, how does the numbering of carbons in the parent chain differ from that used when naming branched alkanes?
6. How is the transfer of heat measured?
7. If an exothermic system is one which produces energy, why must the system be losing heat? 8. If an exothermic reaction causes the temperature of the surroundings to increase, what is
happening on the molecular level in the surroundings? 9. How is an isolated system achieved for heat calculations? 10. Why is water used in a calorimeter?
11. How do you convert from a specific heat of reaction to a molar heat of reaction?
12. How are the terms specific heat of reaction, molar heat of reaction, and heat of reaction related? 13. A 400-g piece of copper piping is taken from outside at 0ºC into a house at 25ºC. How much
heat will be gained by the piece of copper pipe?
14. A block of aluminum has 4.0 kJ of energy added to it. After heating, the block is found to have increased in temperature by 40ºC. What is the mass of the block of aluminum?
15. A student dissolves some potassium fluoride, KF, in 100 mL of water and the temperature changes from 22ºC to 18.5ºC. If the specific heat of solution for KF is –5.72 kJ/g, how much KF was dissolved in the solution?
16. In a student lab, 80.0 mL of 0.800 mol/L potassium hydroxide was neutralized with 30.0 mL of sulfuric acid (an excess). If the temperature increased by 7.6ºC, calculate the molar heat of neutralization for potassium hydroxide.
Answer Section
1. aliphatic, aromatic apliphatic—cyclic, acyclic
acyclic—alkanes, alkenes, alkynes cyclic—cycloalkanes, cycloalkenes
2. The higher the octane-rating number, the better the combustion characteristics of the fuel.
3.
4. Alkanes contain only C–C single bonds, while alkynes contain one or more C–C triple bonds. 5. The numbering of the carbons in alkanes is done such that the lowest numbers are used for the
branches. In alkenes and alkynes, the location of the multiple bond takes precedence over the location of the branches.
6. The transfer heat can be measured by the temperature change that a substance experiences. 7. Since heat is the flow of energy from one substance to another, in an exothermic reaction, heat
flows from the system to the surroundings. Thus, the surroundings gain heat and the system loses heat.
8. Since temperature is a measure of the average kinetic energy of the particles of the
surroundings, if the temperature is increasing, then the average kinetic energy of the particles in the surroundings is being increased by the addition of heat from the exothermic reaction.
9. An isolated system is achieved by using a calorimeter.
10. Water is used because it is readily available and because it has a relatively high specific heat capacity.
hexane 2-methylpentane
11. In order to convert to molar heat of reaction, you would divide the specific heat of reaction by the molar mass of the substance.
12. All of these terms are based on the heat of reaction. They just relate to different quantities of the reactant(s). The heat of the reaction is the heat released or absorbed by a reaction as it proceeds (in a calorimeter for example). The specific heat of reaction is the heat of the reaction per unit mass (gram) of a particular reactant. The molar heat of reaction is the heat of reaction per mole of a particular reactant.
13.
The amount of heat gained by the copper pipe is 3.8 kJ.
14.
The mass of the aluminum block is 1.1 102 g.
15.
The amount of KF dissolved in the solution was 0.26 g.
