Question: The vigorous reaction between aluminum and iodine

> Balance each of the following equations that describe decomposition reactions. a. CaSO4(s) CaO(s) + SO3(g) b. Li2CO3(s) Li2O(s) + CO2(g) c. LiHCO3(s) Li2CO3(s) + H2O(g) + CO2(g) d. C6H6(l) C(s)

> Balance each of the following equations that describe synthesis reactions. a. Fe(s) + S8(s) FeS(s) b. Co(s) + O2(g) Co2O3(s) c. Cl2O7(g) + H2O(l) HClO4(aq)

> Balance each of the following equations that describe synthesis reactions. a. CaO(s) + H2O(l) Ca(OH)2(s) b. Fe(s) + O2(g) Fe2O3(s) c. P2O5(s) + H2O(l) H3PO4(aq)

> According to his prelaboratory theoretical yield calculations, a student’s experiment should have produced 1.44 g of magnesium oxide. When he weighed his product after reaction, only 1.23 g of magnesium oxide was present. What is the student’s percent yi

> By now, you are familiar with enough chemical compounds to begin to write your own chemical reaction equations. Write two examples of what we mean by a combustion reaction.

> Calculate the number of moles of the indicated substance in each of the following samples. a. 41.5 g of MgCl2 b. 135 mg of Li2O c. 1.21 kg of Cr d. 62.5 g of H2SO4 e. 42.7 g of C6H6 f. 135 g of H2O2

> The text explains that one reason why the actual yield for a reaction may be less than the theoretical yield is side reactions. Suggest some other reasons why the percent yield for a reaction might not be 100%.

> A is some factor that tends to make a process occur.

> Are the following processes exothermic or endothermic? a. When solid KBr is dissolved in water, the solution gets colder. b. Natural gas (CH4) is burned in a furnace. c. When concentrated sulfuric acid is added to water, the solution gets very hot. d

> What are the four “stages” of coal formation? How do the four types of coal differ?

> Which of the following pairs of compounds have the same empirical formula? a. acetylene, C2H2, and benzene, C6H6 b. ethane, C2H6, and butane, C4H10 c. nitrogen dioxide, NO2, and dinitrogen tetroxide, N2O4 d. diphenyl ether, C12H10O, and phenol, C6H5O

> Give the empirical formula that corresponds to each of the following molecular formulas. a. sodium peroxide, Na2O2 b. terephthalic acid, C8H6O4 c. phenobarbital, C12H12N2O3 d. 1,4-dichloro-2-butene, C4H6Cl2

> Explain to a friend who has not yet taken a chemistry course what is meant by the empirical formula of a compound.

> What experimental evidence about a new compound must be known before its formula can be determined?

> Why is the “quality” of energy decreasing in the universe?

> Why are petroleum products especially useful as sources of energy?

> Calculate the number of moles of the indicated substance present in each of the following samples. a. 47.2 g of aluminum oxide b. 1.34 kg of potassium bromide c. 521 mg of germanium d. 56.2 µg of uranium e. 29.7 g of sodium acetate f. 1.03 g of sul

> Although the total energy of the universe will remain constant, why will energy no longer be useful once everything in the universe is at the same temperature?

> Consider the gasoline in your car’s gas tank. What happens to the energy stored in the gasoline when you drive your car? Although the total energy in the universe remains constant, can the energy stored in the gasoline be reused once it is dispersed to t

> The combustion of methane, CH4, is an exothermic process. Therefore, the products of this reaction must possess (higher/ lower) total potential energy than do the reactants.

> When a chemical system evolves energy, where does the energy go?

> Balance the following chemical equation, and then answer the question below. CuSO4(aq) + KI(s) CuI(s) + I2(s) + K2SO4(aq) Which reactant is the limiting reactant? Choose the best answer. a. Both CuSO4 and KI are equally limiting be

> Consider the equation: 2A + B 5C. If 10.0 g of A reacts with 5.00 g of B, how is the limiting reactant determined? Choose the best answer and explain. a. Choose the reactant with the smallest coefficient in the balanced chemical

> If the amount of a sample doubles, what happens to the percent composition of each element in the compound?

> The mass fraction of an element present in a compound can be obtained by comparing the mass of the particular element present in 1 mole of the compound to the mass of the compound.

> In studying heat flows for chemical processes, what do we mean by the terms system and surroundings?

> Which of the following statements is(are) true? a. A balanced equation relates the numbers of molecules of reactants and products (or numbers of moles of reactants and products). b. To convert between moles of reactants and moles of products, we use mol

> Calculate the number of moles of the indicated substance present in each of the following samples. a. 21.4 mg of nitrogen dioxide b. 1.56 g of copper(II) nitrate c. 2.47 g of carbon disulfide d. 5.04 g of aluminum sulfate e. 2.99 g of lead(II) chlor

> A is a device used to determine the heat associated with a chemical reaction.

> Thionyl chloride, SOCl2, is used as a very powerful drying agent in many synthetic chemistry experiments in which the presence of even small amounts of water would be detrimental. The unbalanced chemical equation is SOCl2(l) + H2O(l)

> If common sugars are heated too strongly, they char as they decompose into carbon and water vapor. For example, if sucrose (table sugar) is heated, the reaction is C12H22O11(s) 12C(s) + 11H2O(g) What mass of carbon is produced if 1.19

> represents the ability to do work or to produce heat.

> For the balanced chemical equation for the combination reaction of hydrogen gas and oxygen gas 2H2(g) + O2(g) 2H2O(g) explain why we know that 2 g of H2 reacting with 1 g of O2 will not result in the production of 2 g of H2O.

> Elemental phosphorus burns in oxygen with an intensely hot flame, producing a brilliant light and clouds of the oxide product. These properties of the combustion of phosphorus have led to its being used in bombs and incendiary devices for warfare. P4(s)

> Small quantities of ammonia gas can be generated in the laboratory by heating an ammonium salt with a strong base. For example, ammonium chloride reacts with sodium hydroxide according to the following balanced equation: NH4Cl(s) + NaOH(s)

> Sulfurous acid is unstable in aqueous solution and gradually decomposes to water and sulfur dioxide gas (which explains the choking odor associated with sulfurous acid solutions). H2SO3(aq) H2O(l) + SO2(g) If 4.25 g of sulfurous aci

> When yeast is added to a solution of glucose or fructose, the sugars are said to undergo fermentation, and ethyl alcohol is produced. C6H12O6(aq) 2C2H5OH(aq) + 2CO2(g) This is the reaction by which wines are produced from grape j

> Although we usually think of substances as “burning” only in oxygen gas, the process of rapid oxidation to produce a flame may also take place in other strongly oxidizing gases. For example, when iron is heated and placed in pure chlorine gas, the iron “

> Write the formula and calculate the molar mass for each of the following substances. a. carbon dioxide b. aluminum phosphate c. iron(III) carbonate d. lead(II) nitrate e. strontium chloride

> Define the amu. What is one amu equivalent to in grams?

> If baking soda (sodium hydrogen carbonate) is heated strongly, the following reaction occurs: 2NaHCO3(s) Na2CO3(s) + H2O(g) + CO2(g) Calculate the mass of sodium carbonate that will remain if a 1.52-g sample of sodium hydrogen carbon

> Boron nitride reacts with iodine monofluoride in trichlorofluoromethane at 230°C to produce pure nitrogen triiodide and by-product (BF3). BN + 3IF NI3 + BF3 a. What mass of iodine monofluoride must be used to produce 30.0 g of nitrogen tr

> Calcium carbide, CaC2, can be produced in an electric furnace by strongly heating calcium oxide (lime) with carbon. The unbalanced equation is CaO(s) + C(s) CaC2(s) + CO(g) Calcium carbide is useful because it reacts readily with water

> “Smelling salts,” which are used to revive someone who has fainted, typically contain ammonium carbonate, (NH4)2CO3. Ammonium carbonate decomposes readily to form ammonia, carbon dioxide, and water. The strong odor of the ammonia usually restores conscio

> Describe in your own words how the molar mass of the compound below may be calculated. 1 CH4 molecule

> The of a substance is the mass (in grams) of 1 mole of the substance.

> Consider the reaction represented by the chemical equation C(s) + O2(g) CO2(g) Because the coefficients of the balanced chemical equation are all equal to 1, we know that exactly 1 g of C will react with exactly 1 g of O2. True or

> Which of the following statements is true for the reaction of nitrogen gas with hydrogen gas to produce ammonia (NH3)? Choose the best answer. a. Subscripts can be changed to balance this equation, just as they can be changed to balance the charges when

> Although mass is a property of matter we can conveniently measure in the laboratory, the coefficients of a balanced chemical equation are not directly interpreted on the basis of mass. Explain why.

> Write the formula and calculate the molar mass for each of the following substances. a. barium chloride b. aluminum nitrate c. iron(II) chloride d. sulfur dioxide e. calcium acetate

> What does it mean to say that the balanced chemical equation for a reaction describes the stoichiometry of the reaction?

> What quantity serves as the conversion factor between the mass of a sample and how many moles the sample contains?

> Which weighs less, 0.25 mole of xenon atoms or 2.0 moles of carbon atoms?

> Which has the smaller mass, 1 mole of He atoms or 4 moles of H atoms?

> If an average fluorine atom has a mass of 3.16 * 10-23 g, what is the average mass of a chlorine atom in grams?

> If an average sodium atom has a mass of 3.82 * 10-23 g, what is the mass of a magnesium atom in grams?

> What mass of cobalt contains the same number of atoms as 57.0 g of fluorine?

> What mass of hydrogen contains the same number of atoms as 7.00 g of nitrogen?

> Consider a sample of silver weighing 300.0 g. How many atoms of silver are present in the sample? What mass of copper would you need for the copper sample to contain the same number of atoms as the silver sample?

> Suppose you have a sample of sodium weighing 11.50 g. How many atoms of sodium are present in the sample? What mass of potassium would you need to have the same number of potassium atoms as there are sodium atoms in the sample of sodium?

> Give the name and calculate the molar mass for each of the following substances. a. KHCO3 b. Hg2Cl2 c. H2O2 d. BeCl2 e. Al2(SO4)3 f. KClO3

> There are 6.022 * 1023 zinc atoms present in g of zinc.

> There are iron atoms present in 55.85 g of iron.

> The atomic mass of copper is 63.55 amu. What would be the mass of 75 copper atoms? How many copper atoms are contained in a sample of copper that has a mass of 6100.8 amu?

> What is the average atomic mass (in amu) of iron atoms? What would 299 iron atoms weigh? How many iron atoms are present in a sample of iron that has a mass of 5529.2 amu?

> Using the average atomic masses for each of the following elements (see the table inside the front cover of this book), calculate the number of atoms present in each of the following samples. a. 40.08 amu of calcium b. 919.5 amu of tungsten c. 549.4 a

> What do the coefficients of a balanced chemical equation tell us about the proportions in which atoms and molecules react on an individual (microscopic) basis?

> What do we mean by the average atomic mass of an element? What is “averaged” to arrive at this number?

> How many valence electrons does each of the following atoms have? a. titanium, Z = 22 b. iodine, Z = 53 c. radium, Z = 88 d. manganese, Z = 25

> Write the general valence configuration (for example, ns1 for Group 1) for the group in which each of the following elements is found. a. barium, Z = 56 b. bromine, Z = 35 c. tellurium, Z = 52 d. potassium, Z = 19 e. sulfur, Z = 16

> The current model of the atom in which essentially all of an atom’s mass is contained in a very small nucleus, whereas most of an atom’s volume is due to the space in which the atom’s electrons move, was established by a. Millikan’s oil-drop experiment.

> Give the name and calculate the molar mass for each of the following substances. a. H3PO4 b. Fe2O3 c. NaClO4 d. PbCl2 e. HBr f. Al(OH)3

> The of electromagnetic radiation represents the number of waves passing a given point in space each second.

> Electrons found in the outermost principal energy level of an atom are referred to as electrons.

> Which of the following statements is false concerning orbitals? a. An orbital is a region of space where an electron might be found with 90% probability. b. As an electron absorbs more energy, the orbital in which it might be found becomes larger and/o

> When lithium salts are heated in a flame, they emit red light. When copper salts are heated in a flame in the same manner, they emit green light. Why do we know that lithium salts will never emit green light, and copper salts will never emit red light?

> According to Bohr, the electron in the hydrogen atom moved around the nucleus in circular paths called .

> The energy levels of hydrogen (and other atoms) are , which means that only certain values of energy are allowed.

> The lowest possible energy state of an atom is called the state.

> A beam of light can be thought of as consisting of a stream of light particles called .

> The portion of the electromagnetic spectrum between wavelengths of approximately 400 and 700 nanometers is called the region.

> The speed at which electromagnetic radiation moves through a vacuum is called the .

> Using the average atomic masses given inside the front cover of this book, calculate how many moles of each substance the following masses represent. a. 4.15 g of silicon, Si b. 2.72 mg of gold(III) chloride, AuCl3 c. 1.05 kg of sulfur, S d. 0.000901

> Consider the bright line spectrum of hydrogen shown in Fig. 11.10. Which line in the spectrum represents photons with the highest energy? With the lowest energy? Figure 11.10 when excited hydrogen atoms return to lower energy states, they

> In each of the following sets of elements, indicate which element has the smallest atomic size. a. Na, K, Rb b. Na, Si, S c. N, P, As d. N, O, F

> In each of the following sets of elements, which element would be expected to have the highest ionization energy? a. Cs, K, Li b. Ba, Sr, Ca c. I, Br, Cl d. Mg, Si, S

> What are the metalloids? Where are the metalloids found on the periodic table?

> Why do the metallic elements of a given period (horizontal row) typically have much lower ionization energies than do the nonmetallic elements of the same period?

> Which elements in a given period (horizontal row) of the periodic table lose electrons most easily? Why?

> Which of the following elements most easily gives up electrons during reactions: Li, K, or Cs? Explain your choice.

> Give some similarities that exist among the elements of Group 7.

> What types of ions do the metals and the nonmetallic elements form? Do the metals lose or gain electrons in doing this? Do the nonmetallic elements gain or lose electrons in doing this?

> The “Chemistry in Focus” segment Light as a Sex Attractant discusses fluorescence. In fluorescence, ultraviolet radiation is absorbed and intense white visible light is emitted. Is ultraviolet radiation a higher or a lower energy radiation than visible l

> For each of the following unbalanced equations, calculate how many grams of each product would be produced by complete reaction of 12.5 g of the reactant indicated in boldface. Indicate clearly the mole ratio used for the conversion. a. TiBr4(g) + H2(g)

> The “Chemistry in Focus” segment The Chemistry of Bohrium discusses element 107, bohrium (Bh). What is the expected electron configuration of Bh?

> Write the valence shell electron configuration of each of the following elements, basing your answer on the element’s location on the periodic table. a. rubidium, Z = 37 b. barium, Z = 56 c. titanium, Z = 22 d. germanium, Z = 32

> Write the valence-electron configuration of each of the following elements, basing your answer on the element’s location on the periodic table. a. uranium, Z = 92 b. manganese, Z = 25 c. mercury, Z = 80 d. francium, Z = 87

> For each of the following elements, indicate which set of orbitals is filled last. a. radium, Z = 88 b. iodine, Z = 53 c. gold, Z = 79 d. lead, Z = 82

> Based on the elements’ locations on the periodic table, how many 4d electrons would be predicted for each of the following elements? a. ruthenium, Z = 44 b. palladium, Z = 46 c. tin, Z = 50 d. iron, Z = 26

> How many 3d electrons are found in each of the following elements? a. nickel, Z = 28 b. vanadium, Z = 23 c. manganese, Z = 25 d. iron, Z = 26