Question: The mass 1.66 * 10-24 g

> Where did the energy stored in wood, coal, petroleum, and natural gas originally come from?

> The “Chemistry in Focus” segment Burning Calories discusses calories in food. If a food is said to contain 350 calories per serving, determine this value in terms of joules.

> The total energy of the universe is .

> The enthalpy change for a reaction that occurs at constant pressure is (higher than/lower than/the same as) the heat for that reaction.

> In the “Chemistry in Focus” segment Firewalking: Magic or Science?, it is claimed that one reason people can walk on hot coals is that human tissue is mainly composed of water. Because of this, a large amount of heat must be transferred from the coals to

> The “Chemistry in Focus” segment Coffee: Hot and Quick(lime) discusses self-heating cups of coffee using the chemical reaction between quicklime, CaO(s), and water. Is this reaction endothermic or exothermic?

> What quantity of heat is required to raise the temperature of 55.5 g of gold from 20 8C to 45 8C? (See Table 10.1.) Table 10.1 The Specific Heat Capacities of Some Common Substances Specific Heat Capacity (Jig °C) Substance water (/)* (liquid) 4.184

> Calculate the number of moles of carbon atoms present in each of the following samples. a. 1.271 g of ethanol, C2H5OH b. 3.982 g of 1,4-dichlorobenzene, C6H4Cl2 c. 0.4438 g of carbon suboxide, C3O2 d. 2.910 g of methylene chloride, CH2Cl2

> If 100. J of heat energy is applied to a 25-g sample of mercury, by how many degrees will the temperature of the sample of mercury increase? (See Table 10.1.) Table 10.1 The Specific Heat Capacities of Some Common Substances Specific Heat Capacity (

> If 125 J of heat energy is applied to a block of silver weighing 29.3 g, by how many degrees will the temperature of the silver increase? (See Table 10.1.) Table 10.1 The Specific Heat Capacities of Some Common Substances Specific Heat Capacity (Jig

> What quantity of heat energy must have been applied to a block of aluminum weighing 42.7 g if the temperature of the block of aluminum increased by 15.2 °C? (See Table 10.1.) Table 10.1 Table 10.1 The Specific Heat Capacities of Some Comm

> If 69.5 kJ of heat is applied to a 1012-g block of metal, the temperature of the metal increases by 11.4 8(C. Calculate the specific heat capacity of the metal in J/g 8(C.

> Perform the indicated conversions. a. 91.74 kcal into calories b. 1.781 kJ into calories c. 4.318 * 103 J into kilocalories d. 9.173 * 104 cal into kilojoules

> What is the kinetic energy of a particle of mass m moving through space with velocity ν?

> Perform the indicated conversions. a. 625.2 cal into kilojoules b. 82.41 kJ into joules c. 52.61 kcal into joules d. 124.2 kJ into kilocalories

> Arrange the following substances in order of increasing mass percent of nitrogen. a. NO b. N2O c. NH3 d. SNH

> The chemical formula for aspirin is C9H8O4. What is the mass percent for each element in 1 mole of aspirin? (Give your answer to four significant figures.) carbon % hydrogen % охудen %

> Convert the following numbers of kilojoules into kilocalories. (Remember: kilo means 1000.) a. 652.1 kJ b. 1.00 kJ c. 4.184 kJ d. 4.351 * 103 kJ

> Calculate the number of molecules present in each of the following samples. a. 3.54 moles of sulfur dioxide, SO2 b. 3.54 g of sulfur dioxide, SO2 c. 4.46 * 1025 g of ammonia, NH3 d. 4.46 * 1025 moles of ammonia, NH3 e. 1.96 mg of ethane, C2H6

> How are the different types of electromagnetic radiation similar? How do they differ?

> a. How many atoms of carbon are present in 1.0 g of CH4O? b. How many atoms of carbon are present in 1.0 g of CH3CH2OH? c. How many atoms of nitrogen are present in 25.0 g of CO(NH2)2?

> Calculate the number of moles for each compound in the following table. Compound Mass Moles Magnesium phosphate 326.4 g Calcium nitrate 303.0 g Potassium chromate 141.6 g Dinitrogen pentoxide 406.3 g

> Convert the following numbers of calories into kilocalories. (Remember: kilo means 1000.) a. 8254 cal b. 41.5 cal c. 8.231 * 103 cal d. 752,900 cal

> Convert the following numbers of calories or kilocalories into joules and kilojoules (Remember: kilo means 1000.) a. 75.2 kcal b. 75.2 cal c. 1.41 * 103 cal d. 1.41 kcal

> If it takes 654 J of energy to warm a 5.51-g sample of water, how much energy would be required to warm 55.1 g of water by the same amount?

> If 8.40 kJ of heat is needed to raise the temperature of a sample of metal from 15 °C to 20 °C, how many kilojoules of heat will be required to raise the temperature of the same sample of metal from 25 °C to 40 °C?

> Topical hydrocortisone is often used to treat a variety of skin conditions, such as insect bites, eczema, and rashes. Each molecule of hydrocortisone contains 21 atoms of carbon (plus other atoms). The mass percentage of carbon in hydrocortisone is 69.58

> Write the conversion factors that would be necessary to perform each of the following conversions: a. an energy given in calories to its equivalent in joules b. an energy given in joules to its equivalent in calories c. an energy given in calories to

> What mass of sodium hydroxide has the same number of oxygen atoms as 100.0 g of ammonium carbonate?

> A system absorbs 215 kJ of heat, and 116 kJ of work is done on it. Calculate ∆E.

> Calculate the number of molecules present in each of the following samples. a. 4.75 mmol of phosphine, PH3 b. 4.75 g of phosphine, PH3 c. 1.25 * 10-2 g of lead(II) acetate, Pb(CH3CO2)2 d. 1.25 * 10-2 moles of lead(II) acetate, Pb(CH3CO2)2 e. a sampl

> The percent by mass of nitrogen is 46.7% for a species containing only nitrogen and oxygen. Which of the following could be this species? a. N2O5 b. N2O c. NO2 d. NO e. NO3

> What is meant by potential energy? Give an example of an object or material that possesses potential energy.

> How many anions are there in 5.00 g of calcium bromide?

> For an endothermic process, q will have a (positive/negative) sign.

> If q for a process is a positive number, then the system is (gaining/losing) energy.

> Calculate ∆E for each of the following cases. a. q = +65 kJ, w = -22 kJ b. q = +200. kJ, w = -73 kJ c. q = -18 kJ, w = -40. kJ

> The energy, E, of a system represents the sum of the kinetic and potential energies of all particles within the system.

> What do we mean by thermodynamics? What is the first law of thermodynamics?

> Consider the following unbalanced chemical equation: H2S(g) + O2(g) SO2(g) + H2O(g) Determine the maximum number of moles of SO2 produced from 8.0 moles of H2S and 3.0 moles of O2.

> Consider the following unbalanced chemical equation. LiOH(s) + CO2(g) / Li2CO3(s) + H2O(l) If 67.4 g of lithium hydroxide reacts with excess carbon dioxide, what mass of lithium carbonate will be produced?

> Calculate the mass in grams of each of the following samples. a. 0.994 mole of benzene, C6H6 b. 4.21 moles of calcium hydride c. 1.79 * 10-4 moles of hydrogen peroxide, H2O2 d. 1.22 mmol of glucose, C6H12O6 (1 mmol = 1⁄1000 mole) e. 10.6 moles of tin

> A 0.4230-g sample of impure sodium nitrate (contains sodium nitrate plus inert ingredients) was heated, converting all the sodium nitrate to 0.2339 g of sodium nitrite and oxygen gas. Determine the percent of sodium nitrate in the original sample.

> Consider the following unbalanced chemical equation for the combustion of pentane (C5H12): C5H12(l) + O2(g) CO2(g) + H2O(l) If a 20.4-gram sample of pentane is burned in excess oxygen, what mass of water can be produced, as

> Before going to lab, a student read in his lab manual that the percent yield for a difficult reaction to be studied was likely to be only 40. % of the theoretical yield. The student’s prelab stoichiometric calculations predict that the theoretical yield

> If sodium peroxide is added to water, elemental oxygen gas is generated: Na2O2(s) + H2O(l) NaOH(aq) + O2(g) Suppose 3.25 g of sodium peroxide is added to a large excess of water. What mass of oxygen gas will be produced?

> If an average sodium atom weighs 22.99 amu, how many sodium atoms are contained in 1.98 * 1013 amu of sodium? What will 3.01 * 1023 sodium atoms weigh?

> Using the average atomic masses given in Table 8.1, calculate the number of atoms present in each of the following samples. a. 160,000 amu of oxygen b. 8139.81 amu of nitrogen c. 13,490 amu of aluminum d. 5040 amu of hydrogen e. 367,495.15 amu of so

> Although exact isotopic masses are known with great precision for most elements, we use the average mass of an element’s atoms in most chemical calculations. Explain.

> A certain transition metal ion (Mn+) forms a compound with oxygen (MxOy). The molar mass of the compound is 250.2 g/ mol. If the charge on the transition metal ion is 13, what is the identity of the transition metal, M? a. Th b. Ti c. Hg d. Ru e. Ag

> Calculate the number of grams of lithium that contain the same number of atoms as 1.00 kg of zirconium.

> Calculate the mass in grams of each of the following samples. a. 0.251 mole of ethyl alcohol, C2H6O b. 1.26 moles of carbon dioxide c. 9.31 * 10-4 moles of gold(III) chloride d. 7.74 moles of sodium nitrate e. 0.000357 mole of iron

> A compound was analyzed and found to contain the following percentages of elements by mass: carbon, 79.89%; hydrogen, 20.11%. a. Determine the empirical formula of the compound. b. Which of the following could be a molar mass of the compound? i. 13.01

> You have a sample of copper (Cu) and a sample of aluminum (Al). You have an equal number of atoms in each sample. Which of the following statements concerning the masses of the samples is true? a. The mass of the copper sample is more than twice as grea

> Given that the molar mass of carbon tetrachloride, CCl4, is 153.8 g, calculate the mass in grams of 1 molecule of CCl4.

> For the following chemical reactions, determine the precipitate produced when the two reactants listed below are mixed together. Indicate “none” if no precipitate will form. Formula of Precipitate Sr(NO3)2(aq) + К,

> For the following chemical reactions, determine the precipitate produced when the two reactants listed below are mixed together. Indicate “none” if no precipitate will form. Formula of Precipitate Na,SO4(aq) + Pb(

> Find the item in column 2 that best explains or completes the statement or question in column 1. Column 1 (1) 1 amu (2) 1008 amu (3) mass of the “average” atom of an element (4) number of carbon atoms in 12.01 g of carbon (5) 6.022 * 1023 molecules

> Consider a solution with the following ions present: NO3-, Pb2+, K+, Ag+, Cl-, SO42-, PO43- All are allowed to react, and there are plenty available of each. List all of the solids that will form using the correct formulas in your explanation.

> Corrosion of metals costs us billions of dollars annually, slowly destroying cars, bridges, and buildings. Corrosion of a metal involves the oxidation of the metal by the oxygen in the air, typically in the presence of moisture. Write a balanced equation

> When a sodium chromate solution and aluminum bromide solution are mixed, a precipitate forms. Complete and balance the equation for this reaction, including the phases of each reactant and product.

> Consider the balanced equation C3H8(g) + 5O2(g) 3CO2(g) + 4H2O(g) What mole ratio enables you to calculate the number of moles of oxygen needed to react exactly with a given number of moles of C3H8 (g)? What mole ratios enable you to c

> Calculate the mass in grams of each of the following samples. a. 6.14 * 10-4 moles of sulfur trioxide b. 3.11 * 105 moles of lead(IV) oxide c. 0.495 mole of chloroform, CHCl3 d. 2.45 * 10-8 moles of trichloroethane, C2H3Cl3 e. 0.167 mole of lithium

> Hydrogen gas reacts with each of the halogen elements to form the hydrogen halides (HF, HCl, HBr, HI). Calculate the percent by mass of hydrogen in each of these compounds.

> For each of the following nonmetals, how many electrons will each atom of the nonmetal gain in reacting with a metal? a. oxygen b. fluorine c. nitrogen d. chlorine e. sulfur

> For each of the following metals, how many electrons will the metal atoms lose when the metal reacts with a nonmetal? a. sodium b. potassium c. magnesium d. barium e. aluminum

> True or false? For the reaction represented by the balanced chemical equation Mg(OH)2(aq) + 2HCl(aq) 2H2O(l) + MgCl2(aq) for 0.40 mole of Mg(OH)2, 0.20 mol of HCl will be needed.

> A compound with the empirical formula CH2 was found to have a molar mass of approximately 84 g. What is the molecular formula of the compound?

> A compound with empirical formula CH was found by experiment to have a molar mass of approximately 78 g. What is the molecular formula of the compound?

> Balance each of the following equations that describe decomposition reactions. a. NaHCO3(s) Na2CO3(s) + H2O(g) + CO2(g) b. NaClO3(s) NaCl(s) + O2(g) c. HgO(s) Hg(l) +

> Balance each of the following equations that describe synthesis reactions. a. FeO(s) + O2(g) Fe2O3(s) b. CO(g) + O2(g) CO2(g) c. H2(g) + Cl2(g) HCl(g) d. K(s) + S8(s)

> Which of the following statements is/are true regarding solutions? a. If a solute is dissolved in water, then the resulting solution is considered aqueous. b. If two solutions are mixed and no chemical reaction occurs, then a net ionic equation cannot

> What are the molecular and empirical formulas for the following molecule? Explain your reasoning. H Н-С—ОН Н. HO OH H HO `H. С—С H OH

> Calculate the mass in grams of each of the following samples. a. 1.25 moles of aluminum chloride b. 3.35 moles of sodium hydrogen carbonate c. 4.25 millimoles of hydrogen bromide (1 millimole = 1⁄1000 mole) d. 1.31 * 10-3 moles of uranium e. 0.00104

> A compound with empirical formula C2H5O was found in a separate experiment to have a molar mass of approximately 90 g. What is the molecular formula of the compound?

> For the reaction 16Fe(s) + 3S8(s) 8Fe2S3(s), show how electrons are gained and lost by the atoms.

> For the reaction 2Al(s) + 3I2(s) 2AlI3(s), show how electrons are gained and lost by the atoms. © Cengage Leaming

> What strong acid and what strong base would react in aqueous solution to produce the following salts? a. potassium perchlorate, KClO4 b. cesium nitrate, CsNO3 c. potassium chloride, KCl d. sodium sulfate, Na2SO4

> Write the balanced molecular, complete ionic, and net ionic equations for the reaction of ammonium sulfide with iron(III) chloride.

> For each of the following unbalanced molecular equations, write the corresponding balanced net ionic equation for the reaction. a. HCl(aq) + AgNO3(aq) AgCl(s) + HNO3(aq) b. CaCl2(aq) + Na3PO4(aq) Ca3(PO4)2(s) + Na

> Below are indicated the formulas of some salts. Such salts could be formed by the reaction of the appropriate strong acid and strong base (with the other product of the reaction being, of course, water). For each salt, write an equation showing the forma

> When 1.00 mg of lithium metal is reacted with fluorine gas (F2), the resulting fluoride salt has a mass of 3.73 mg. Calculate the empirical formula of lithium fluoride.

> Which of the following correctly identifies the precipitate formed when aqueous solutions of the following substances are mixed? Mixed Solutions……………………………………Precipitate Formed a. Na2SO4 (aq) + BaCl2(aq) BaSO4 b

> A favorite demonstration among chemistry instructors, to show that the properties of a compound differ from those of its constituent elements, involves iron filings and powdered sulfur. If the instructor takes samples of iron and sulfur and just mixes th

> Calculate the number of moles of the indicated substance present in each of the following samples. a. 1.95 * 10-3 g of lithium carbonate b. 4.23 kg of calcium chloride c. 1.23 mg of strontium chloride d. 4.75 g of calcium sulfate e. 96.2 mg of nitro

> Complete and balance each of the following molecular equations for strong acid/strong base reactions. Underline the formula of the salt produced in each reaction. a. HNO3(aq) + KOH(aq) b. H2SO4(aq) + Ba(OH)2(aq) c. HClO4(aq) + NaOH(aq)

> Without first writing a full molecular or ionic equation, write the net ionic equations for any precipitation reactions that occur when aqueous solutions of the following compounds are mixed. If no reaction occurs, so indicate. a. iron(III) nitrate and

> Which of the following ions form compounds with Ag+ that are generally soluble in water? a. S2- b. Cl2 c. NO3- d. SO42- e. Na+

> When 3.269 g of zinc is heated in pure oxygen, the sample gains 0.800 g of oxygen in forming the oxide. Calculate the empirical formula of zinc oxide.

> Balance each of the following equations that describe oxidation– reduction reactions. a. Al(s) + Br2(l) AlBr3(s) b. Zn(s) + HClO4(aq) Zn(ClO4)2(aq) + H2(g) c. Na(s) + P(s) Na3P(s) d. CH4(g) + Cl2(g)

> 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?