Sun Honors Chemistry 2 nd Semester Review Problems
nd
The following problems are continued from the Midterm Review problems. These problems are to help you to review some, but not all, of the concepts we learned during the 2 nd semester. You may review Midterm review to get some practice for concepts we learned during the 1 st semester. A detailed guideline for the final exam can be found in the document Final Exam Review Guide Honors 11-12. The best way to study is to follow the instructions in that document and check your understandings for each objective listed there.
1. How do interactions observed in the Sticky Tape experiment help us understand the attractions between ions, atoms and molecules in compounds?
2. Distinguish between molecular and ionic solids.
Particles in molecular solids are separate molecules that attract one another. When dissolved in water, the solution does NOT conduct electricity; e.g., C6H12O6. Give reasoning at particle level.
Particles in ionic solids are charged particles (ions). Cations (+) and anions (-) are in an alternating lattice pattern. The formula unit represents the simplest integer ratio
(empirical formula) of the ions; e.g. CaCl2. When dissolved in water, the solution does conduct electricity. Give reasoning at particle level.
What other property differences between ionic and molecular compound can be explained by the particle model you describe above?
Modeling Chemistry 1 1st Sem Review-v2.1

Sun Honors Chemistry 2 nd Semester Review Problems
3. Demonstrate knowledge of the meaning of a chemical formula in terms of atoms and molecules.
Example: Identify the number of atoms and ions of each kind in each compound.
Pb(NO3)2 Na3PO4 Al2(SO4)3
4. Name ionic and molecular compounds from formulas and vice versa.
Write the formula or name of binary compounds (formed from two kinds of atoms). a potassium iodide b. nitrogen trichloride c.
sodium oxide d. aluminum chloride e.
tin(IV) chloride f. iron(III) sulfide g. phosphorus tribromide h.
SnO i. SnBr4 j. SO2 k. Al2O3 l.
N2O5 m.
CaO
Write the formula or name of compounds formed from polyatomic ions. n.
calcium nitrate o.
potassium phosphate p.
aluminum acetate q.
ammonium sulfate r.
Al(OH)3 s.
Cu2SO4 t.
(NH4)2CO3
Recognize that atoms and molecules are too small to count directly. We use a counting unit – mole – to count them by bulk so we can determine how many atoms/molecules there are in a measurable sample by finding the mass. Therefore, mass of one mole of a substance (molar mass) can be used as a conversion factor between mass and mole. Mole was originally defined as the number of atoms in 1 gram of hydrogen. Molar mass of any substance can be found from the relative mass in the periodic table. Current definition of one is the number of atoms in 12 grams
Carbon-12.
Modeling Chemistry 2 1st Sem Review-v2.1

Sun Honors Chemistry 2 nd Semester Review Problems
1. Be able to determine the molar mass of a compound.
Example: Determine the molar masses. Pb(NO3)2
=
BaSO4
2. Determine the number of atoms or moles using Avogadro’s number and the molar mass of a compound.
Example: 12 g MgCl2 x moles MgCl2
3.0 moles MgCl2 x x = ions Cl-
3. Determine the empirical and molecular formulas from mass data.
A compound is composed of 7.20 g of carbon, 1.20 g of hydrogen, and 9.60 g of oxygen. The molar mass of the compound is 1.8x10
2 g. Find the empirical and molecular formulas for this compound.
4. Distinguish between the meaning of coefficients and subscripts in a balanced chemical equation.
Example: Draw particle diagrams to represent the following reaction:
Al + FeSO4 --> ________ + _____ reaction type?
5. Write complete balanced reaction equations from word descriptions.
Change these word equations to symbols. Identify type of reactions. a. barium chlorate, when heated, produces barium chloride and oxygen gas. b. ethane, C2H6, burns in air to produce _________________ and __________. c. lime, (calcium oxide) reacts with sulfur dioxide to form calcium sulfite. d. chromium reacts with oxygen to produce chromium(III) oxide. e. potassium carbonate powder reacts with hydrochloric acid to produce ___________, carbon dioxide and water.
Modeling Chemistry 3 1st Sem Review-v2.1

Sun Honors Chemistry 2 nd Semester Review Problems
6. Demonstrate knowledge that matter is conserved in ordinary chemical reactions.
Example: If 3.6 g of water is decomposed, 3.2 g of oxygen and what mass of hydrogen will be produced?
1. Use balanced equation and the BCA table to predict the quantity of reactant or product involved in a chemical reaction.
Calculate the number of grams of potassium chloride, KCl, that will be formed by the decomposition of 6.45 g of potassium chlorate, KClO3.
2. Determine percent yield when actual yield is known.
A chemist burns 160 g of Al in air to produce 260 g of solid aluminum oxide. Determine the theoretical yield. Determine the percent yield.
3. From a representation of a reaction mixture before and after the reaction, determine the balanced equation for a reaction.
Reaction equation ________________________________________________________
4. Use limiting reactant to predict amount of product formed.
How many grams of water can be formed when 2.87 g of CH4 reacts with 4.58 g of O2?
(Hint: predict reaction products first)
Modeling Chemistry 4 1st Sem Review-v2.1

Sun Honors Chemistry 2 nd Semester Review Problems
5. Apply law of partial gas pressure, molar volume at STP and/or ideal gas law (PV=nRT) to solve stoichiometry problems involving gases.
The above reaction between CH
4
and oxygen was carried out in a container with constant volume of 5.00 L. After the reaction was completed, the resulting mixture was cooled to 62.6°C. What is the total pressure in the container? a) What are the substances in the container at this point? What are in gas phase?
(remember that water exists as liquid at 62.6°C but there is always water vapor in the gas phase above the surface of water) b) How many moles of each gaseous substance are in the mixture? (no need to calculate moles of water vapor) Hint: Check the after line in your BCA table in question #4. c) What is the partial pressure of each gas (not water) in the mixture? Hint: you already know the volume, mole and temperature of each gas. d) What is the total pressure (in atm) in the container? (Water vapor pressure at 62.6°C is 171 mmHg.)
6. Determine the amount of energy absorbed or released by a chemical reaction from the given ∆H of reaction and stoichiometry. a) The enthalpy change of the combustion of CH
4
is ∆H = - 882.0 kJ/mol. Is this reaction endo- or exothermic? Write the reaction equation in two ways: 1) with the energy in kJ written on the correct side of equation; 2) in ∆H notation. b) How many grams of water would be formed if 147 kJ of energy is released by the reaction?
Modeling Chemistry 5 1st Sem Review-v2.1

Sun Honors Chemistry 2 nd Semester Review Problems c) If the amount of energy released by the reaction in question #4 is transferred to
1.00 kg of water, what would be the temperature change of water? Increase or decrease? Specific heat capacity of water is 4.18 J/(g°C).
7. Use molar concentration (molarity) of solution as a conversion factor in stoichimometry involving volume and mole of solutions. a) How many mL of 3.04 M hydrochloric acid (HCl) is consumed in the reaction with
2.26 g of zinc? (predict reaction products and write a balanced reaction equation) b) What is the volume of the gas product at STP? (You must use the most direct method.) c) What is the volume of the gas product at 25°C and 752 mmHg? Try in two ways: the ideal gas law and PVnT table with proportional factors.
Modeling Chemistry 6 1st Sem Review-v2.1