Exam 2

The oxidation number of chlorine in the compound FeCl3 is

A) -1.

The formula weight of Al2(SO4)3 is ________ grams.

C) 342.14

Which quantity contains Avogadro's number of molecules?

C) 98 g of H2SO4

In a precipitation reaction the insoluble product can be identified by the symbol

(S)

In the reaction shown, what is the mole ratio that would be used to determine the number of moles of oxygen needed to react with 3.2 moles of C4H10? 2 C4H10 + 13 O2 --> 8 CO2 + 10 H2O

13 moles O2 _____________________ 2 moles C4H10

Which reaction is not an example of a redox reaction?

2 (NH4)3PO4(aq) + 3 Ba(NO3)2(aq) Ba3(PO4)2(s) + 6 NH4NO3(aq)

2 AgNO3(aq) + K2SO4(aq) 2 KNO3(aq) + Ag2SO4(s) The net ionic reaction for the balanced equation shown above is

2 Ag+(aq) + SO42-(aq) --> Ag2SO4(s)

The balanced equation for the reaction occurring when iron(III) oxide, a solid, is reduced with pure carbon to produce carbon dioxide and molten iron is

2 Fe2O3(s) + 3 C(s) 4 Fe l) + 3 CO2(g).

Consider the balanced equation shown and identify the statement that is not true. Na2SO4(aq) + BaCl2(aq) 2 NaCl(aq) + BaSO4(s)

2 NaCl (aq) could also be correctly written as Na2Cl2 (aq).

Consider the reaction shown: 304.0 kcal + 4 PCl3(l) --> P4(s) + 6 Cl2(g)

27.67; consumed

The balanced equation for the reaction occurring when calcium nitrate solution is mixed with sodium phosphate solution is

3 Ca(NO3)2(aq) + 2 Na3PO4(aq) Ca3(PO4)2(s) + 6 NaNO3(aq).

34) In the reaction shown, what is the mole ratio that would be used to determine the number of moles of H2 that would be produced when 3.5 moles of AlCl3 are produced? 2 Al + 6 HCl -> 2 AlCl3 + 3 H2

3 moles H2 ____________________ 2 moles AlCl3

Based on the reaction shown, which statement is true? N2 + O2 2 NO H = 43.2 kcal

43.2 kcal are consumed when 1.00 mole of O2 reacts.

Based on the reaction shown, which statement is true? S + O2 SO2 + 70.8 kcal

70.8 kcal are produced when 32.1 g of sulfur reacts.

Which statement concerning the mole is not correct? A) A mole of a diatomic element contains 2 × NA moles of atoms of the element. B) The molar mass of any compound is equal to its molecular weight in grams. C) A mole of any compound contains one mole of each kind of atom found in that compound. D) A mole of metal contains NA atoms of that metal. E) All of these statements are correct.

A mole of any compound contains one mole of each kind of atom found in that compound.

The oxidation number of sulfur in calcium sulfate, CaSO4, is

A) +6.

Calculate the number of moles of aspirin, C9H8O4, in 4.0 gram sample.

A) 0.022 moles

How many molecules are present in 3.25 mol of C2H6O?

A) 1.96 × 1024 molecules

The molecular weight of PCl3 is ________ amu.

A) 137.33

If a tablet of acetaminophen, C8H9NO2, weighs 324 mg, how many moles are there in the tablet?

A) 2.15 × 10-3

How many molecules are present in 4.25 mol of CCl4?

A) 2.56 × 1024 molecules

When the reaction shown is correctly balanced, the coefficients are: ________ HBr + ________ Ca(OH)2 ________ CaBr2 + ________ H2O

A) 2; 1; 1; 2

When the reaction shown is correctly balanced, the coefficients are: ________ KClO3 ________ KCl + ________ O2

A) 2; 2; 3

When the following reaction is balanced, the coefficient in front of carbon dioxide is: ________ C5H12 + ________ O2 ________ CO2 + ________ H2O

A) 5

A thimble of water contains 4.0 × 1021molecules. The number of moles of H2O is

A) 6.6 × 10-3.

he reaction N2 + 3 H2 2 NH3 is used to produce ammonia. When 450. g of hydrogen was reacted with nitrogen, 1575 g of ammonia were produced. What is the percent yield of this reaction?

A) 62.1%

The combustion of propane gas (C3H8) is used to fuel barbeque grills. In order to produce 5.65 moles of water how many moles of oxygen gas are needed? C3H8(g) + 5 O2(g) 3 CO2(g) + 4 H2O(l)

A) 7.06 mol

Consider the reaction shown: N2 + O2 --> 2 NO DELTA H = 43.2 kcal When 50.0 g of N2 react, ________ kcal will be ________.

A) 77.1; consumed

The number of grams in 0.350 mol of Na is

A) 8.05

A solid sample at room temperature spontaneously sublimes forming a gas. This change in state is accompanied by which of the changes in the sample?

A) Entropy and energy increase.

Which factors would decrease the rate of a reaction? I. Lowering the temperature II. Increasing the concentration of reactants III. Adding a catalyst

A) I only

All of the reactions shown are oxidation-reduction reactions except

A) K2SO4(aq) + BaCl2(aq) BaSO4(s) + 2 KCl(aq).

The percentage yield of a reaction can best be described as the ________ times 100%.

A) amount of product obtained divided by the maximum possible amount of product

The element chlorine is very reactive as a(an) ________ agent because it readily ________ electrons to form the chloride ion.

A) oxidizing; gains

Which of the following can affect the activation energy of a reaction?

A) use of a catalyst

The oxidation number of iron in the compound FeBr3 is

B) +3.

Calculate the enthalpy for the combustion of propane shown using the given bond dissociation energies: C3H8 + 5 O2 3 CO2 + 4H2O Number and types of bonds in each molecule: C3H8 (2 C-C, 8 C-H bonds); O2 (1 O=O); (2 C=O bonds); (2 O-H bonds). Bond dissociation energies: C-C (347 kJ/mol); C-H (413 kJ/mol); O=O (498 kJ/mol; C=O (799 kJ/mol); O-H (467 kJ/mol)

B) -2042 kJ

The molar mass of Fe(OH)3 is ________ g.

B) 106.87

How much Ca(NO3)2 should be weighed out to have 0.650 mol?

B) 107 g

The combustion of propane gas is used to fuel barbeque grills. If 4.65 moles of propane, C3H8, are burned in a grilling session, how many moles of carbon dioxide gas are formed? C3H8(g) + 5 O2(g) 3 CO2(g) + 4 H2O(l)

B) 14.0 mol

The Haber process is used to make ammonia, which is an important source of nitrogen that can be metabolized by plants. Using the equation below, determine how many moles of ammonia will be formed from 8.55 mole of nitrogen. N2(g) + 3 H2(g) ---> 2 NH3(g)

B) 17.1 mol

In the reaction 2 C + O2 2 CO, how many moles of carbon are needed to produce 66.0 g of carbon monoxide?

B) 2.36

In a reaction to produce chlorine gas, the theoretical yield is 25.6g. What is the actual yield of the reaction if the percent yield is 83.5%?

B) 21.4 g

42.0 g Cl2 contains ________ molecules Cl2.

B) 3.57 × 1023

The Haber process is used to make ammonia, which is an important source of nitrogen that can be metabolized by plants. Using the equation below, determine how many kilograms of ammonia will be formed from 89.5 kg of hydrogen. N2(g) + 3H2(g) --> 2NH3(g)

B) 502 kg

The molar mass of butane, C4H10, is ________ grams.

B) 58.12

The fuel for your car is a mixture of octane and several other hydrocarbons. What mass of CO2 will be produced when 125 g of C8H18 react completely in the following equation? 2 C8H18 + 25 O2 --> 16 CO2 + 18 H2O

B) 6.03 g

When the reaction shown is balanced, there are ________ atoms of oxygen and ________ atoms of hydrogen on each side. _______ (NH4)2SO4(aq) + _______ Ba(C2H3O2)2(aq) _______ BaSO4(s) + _______

B) 8; 14

Which is the limiting reactant when 3.00 g of calcium are reacted with 8.00 g of water to produce hydrogen gas in the following equation? Ca(s) + 2 H2O(l) --> Ca(OH)2(aq) + H2(g)

B) Ca

Which of the following processes involve an increase in entropy of the system? Mothballs vaporize in a closet. II. Blocks are assembled into a house. III. Crystals grow from a sugar solution. IV. Recyclable plastics are sorted. V. Cake mix is manufactured from five basic ingredients.

B) I, V

Which is the correct equation for the reaction of magnesium with hydrochloric acid to produce hydrogen and magnesium chloride?

B) Mg + 2 HCl -> H2 + MgCl2

The following equation represents the formation of nitrogen dioxide, a major component of smog, 2 NO + O2 --> 2 NO2 If 0.68 mole of NO is reacted with 0.79 mole of O2 to produce NO2, the limiting reactant is

B) NO.

In which of the following is the oxidation number for oxygen equal to zero?

B) O2

Interpret in words the equation shown. P4O10(s) + 6 H2O(l) 4 H3PO4(aq)

B) One mole of solid tetraphosphorus decaoxide reacts with six moles of liquid water to produce four moles of phosphoric acid solution.

For a chemical reaction to occur, all of the following must happen except

B) a large enough number of collisions must occur.

Which of the following contains kinetic energy?

B) a moving car

All of the statements regarding the symbol DELTA G are true except it 29) A) allows us to identify an endergonic reaction. B) allows us to identify an exothermic reaction. C) describes the effect of both enthalpy and entropy on a reaction. D) allows us to predict the spontaneity of a reaction. E) refers to the free energy of the reaction.

B) allows us to identify an exothermic reaction.

A process or reaction which takes in heat from the surroundings is said to be

B) endothermic.

All of the statements concerning free energy and spontaneity are true except A) if the value of G for a reaction is negative, the reaction is said to be spontaneous. B) enthalpy and entropy are of equal importance in determining the spontaneity of a reaction. C) a reaction which is nonspontaneous at low temperature cannot be spontaneous at higher temperatures. D) if the value of G for a reaction is 55.2 kcal, the value of G for the reverse reaction will be -55.2 kcal. E) the speed of a reaction is not influenced by its spontaneity.

B) enthalpy and entropy are of equal importance in determining the spontaneity of a reaction.

A process or reaction which releases heat to the surroundings is said to be

B) exothermic.

In a typical oxidation-reduction reaction the electrons are transferred

B) from what is being oxidized to the substance being reduced.

A rapid reaction is distinguished by

B) having a small value of activation energy.

In the process of dissolving sugar in water, the entropy increases. This means that the sign of DELTA S is ________, and that the randomness of the system ________.

B) positive; increases

Consider the reaction: A + 2 B <-----> 2 C + D

C) [C]2[D] ___________ [A][B]2

What is the oxidation number of oxygen in hydrogen peroxide, H2O2?

C) -1

A student weighed 0.550 g of lithium chloride, LiCl, to use in a reaction. How many moles is this?

C) 0.0130

As a pure element the oxidation number of zinc is ________, but in compounds such as ZnCO3 its oxidation number is ________.

C) 0; +2

105 g of MgCl2 contains ________ mol MgCl2.

C) 1.10

How many molecules are there in 3.00 moles of NH3?

C) 1.81 × 1024 molecules

Ammonium sulfate is a common component of fertilizer. Calculate it's formula weight.

C) 132.13 amu

The formula mass of copper(II) chloride is ________ g.

C) 134.45

The number of grams in 2.65 mol of SO2 is

C) 170.

Consider the reaction shown: P4(s) + 10 Cl2(g) --> 4 PCl5(s) + 452 kcal When 50.00 g of P4 react, ________ kcal will be ________.

C) 182.4; produced

When the following reaction is balanced, the coefficient in front of oxygen is: ________ C8H18 + ________ O2 ________ CO2 + ________ H2O

C) 25

Calculate the enthalpy for the following reaction: N2 + O2 2 NO given the following bond dissociation energies: N2 = 226 kcal/mol O2 = 119 kcal/mol NO = 145 kcal/mol.

C) 55 kcal/mol

n the reaction shown, how many moles of HCl are needed to react with 2.4 moles of Al? 2 Al + 6 HCl 2 AlCl3 + 3 H2

C) 7.2

A solution containing 145.0 g AgNO3 is mixed with a CaCl2 solution and 98.4 of AgCl is recovered. Calculate the % yield of the reaction.

C) 80.44%

For the reaction given below, what quantity of heat will be produced if 90.0 g of C3H8 are consumed in the reaction? C3H8 + 5 O2 --> 3 CO2 + 4 H2O+ 488 kcal

C) 996 kcal

Which factors would increase the rate of a chemical reaction? I. Increasing the temperature II. Removing products as they are formed III. Adding a catalyst

C) I, II, and III

Based on the bond energies given for each of the following which is the most stable?

C) NN 946 kJ/mol

Which of the following conditions characterizes a system in a state of chemical equilibrium?

C) Reactants are being consumed at the same rate they are being produced.

In order to determine if a reaction is at equilibrium which of the following must be true?

C) The rate at which the forward and reverse reactions are proceeding are equal.

Which process is not likely to be considered reversible?

C) cutting down a tree

In the reaction A + B AB, which of the following will not increase the rate?

C) decreasing the temperature

To simplify comparisons, the energy value of fuels is expressed in units of

C) kcal/g.

In the reaction shown, ________ is the oxidizing agent because it ________. Ni(s) + CuCl2(aq) Cu(s) + NiCl2(aq)

CuCl2; gets reduced

50.0 g of Cl2 contains ________ mol Cl2.

D) 0.705

Acid rain forms in the upper atmosphere by the reaction of sulfur trioxide with water forming sulfuric acid. Calculate the mass in grams of 5.65 × 1021 molecules of SO3.

D) 0.751 g

When the reaction shown is correctly balanced, the coefficients are: ________ HNO3 + ________ KOH ________ KNO3 + ________ H2O

D) 1; 1; 1; 1

How many moles of NaHCO3 are present in a 2.00 g sample?

D) 2.38 × 10-2 mol

When the reaction shown is correctly balanced, the coefficients are: ________ C6H14(l) + ________ O2(g) ________ CO2(g) + ________ H2O(g)

D) 2; 19; 12; 14

When the reaction shown is correctly balanced, the coefficients are: ________ Li + ________ Br2 ________ LiBr

D) 2; 1; 2

The active ingredient in many antacid tablets is calcium carbonate, CaCO3. How many moles of calcium carbonate are contained in a tablet weighing 550. mg?

D) 5.51 × 10-3

In a reaction to produce ammonia, the theoretical yield is 420.g. What is the percent yield if the actual yield is 350.g?

D) 83.3%

The formula weight of ammonium carbonate, (NH4)2CO3 is ________ amu.

D) 96.09

Which of the following will affect all reaction rates? 48) A) the temperature of the reactants B) the presence of a catalyst C) the concentrations of the reactants D) All are correct.

D) All are correct.

Which of the following equations is not balanced?

D) C7H16 + O2 7 CO2 + 8 H2O

In the redox reaction shown, ________ is oxidized and becomes ________. Fe(s) + CuCl2 aq) Cu(s) + FeCl2(aq)

D) Fe; Fe2+

Which one of the following substances is produced during an acid/base (or neutralization) reaction?

D) H2O

In order to form the salt calcium sulfate, which acid and base combination should you choose?

D) H2SO4 and Ca(OH)2

Which statement concerning the mole concept is not true? 2) A) The molar mass of a metal is its atomic weight expressed in grams. B) One mole of water contains the same number of molecules as one mole of ammonia. C) The mole concept makes a connection between the mass of a substance and the number of particles or units of that substance. D) One mole of any compound contains one mole of atoms. E) One mole of sodium contains the same number of atoms as one mole of carbon.

D) One mole of any compound contains one mole of atoms.

2 Al2O3(s) --> 4 Al(s) + 3 O2(g) DELTA G = +138 kcal Consider the contribution of entropy to the spontaneity of this reaction. As written, the reaction is ________, and the entropy of the system ________.

D) non-spontaneous; increases

31) A process which is unfavorable with respect to enthalpy, but favorable with respect to entropy could

D) occur at high temperatures, but not at lower temperatures.

A reaction which is unfavorable with respect to entropy, but favorable with respect to enthalpy could

D) occur at low temperatures but not at higher temperatures.

In the following reaction which species is being oxidized and which is being reduced? 2 Cr(s) + 3 Cl2(g) 2 CrCl3(s)

D) oxidized: Cr; reduced: Cl2

When a substance loses electrons it is ________; the substance itself is acting as a(an) ________ agent.

D) oxidized; reducing

When potassium hydroxide and hydrobromic acid are combined the products are

D) potassium bromide and water.

All of the statements regarding redox reactions are true except 35) A) halogens usually behave as oxidizing agents because they readily gain electrons. B) a reducing agent causes another substance to be reduced. C) metal ions are produced when pure metals are oxidized. D) when a substance is oxidized its charge (or oxidation number) decreases. E) alkali metals often behave as reducing agents because they readily lose electrons.

D) when a substance is oxidized its charge (or oxidation number) decreases.

How much heat is released during the combustion of methane using the given bond dissociation energies: CH4 + 2 O2 CO2 + 2H2O Number and types of bonds in each molecule: CH4 (4 C-H bonds); O2 (1 O=O); (2 C=O bonds); (2 O-H bonds). Bond dissociation energies: C-C (347 kJ/mol); C-H (413 kJ/mol); O=O (498 kJ/mol; C=O (799 kJ/mol); O-H (467 kJ/mol)

E) -8181 kJ

How many grams of C will be consumed when 5.00 grams of Na2SO4 react according to the balanced reaction shown? Na2SO4 + 2 C --> Na2S + 2 CO2

E) 0.844 g

In the balanced reaction shown, the mole ratio of Fe2S3 to O2 is Fe2S3 + 4 O2 2 FeO + 3 SO2

E) 1 to 4.

How many moles of CO2 are produced when 2.5 moles of O2 react according to the following equation? C3H5 + 5 O2 3 CO2 + 4 H2O

E) 1.5

31) Determine the number of moles of water produced when one mole of NH3 reacts according to the balanced reaction shown. 4 NH3 + 5 O2 -> 4 NO + 6 H2O

E) 1.50

How many grams of fluorine are required to produce 20.0 grams of FeF3 from the reaction shown? 2 Fe + 3F2 --> 2 FeF3

E) 10.1 g

The number of grams in 7.00 moles of N2 is

E) 196.

In the correctly balanced reaction, the coefficient for H2O is: ________ Al(OH)3 + ________ H2SO4 ________ Al2(SO4)3 + ________ H2O

E) 6

What does the balanced equation given below mean? CH4 + 2 O2 --> CO2 + 2H2O

E) A and C are correct.

Which reaction is an example of an acid-base reaction?

E) H2SO4(aq) + Ca(OH)2(aq) CaSO4(aq) + 2 H2O(l)

Which of the following equations is not balanced?

E) SO2 + O2 SO3

Which of the following contains potential energy?

E) a book on a table

Reduction is the process of A) forming an anion from a neutral atom. B) gaining hydrogen. C) gaining electrons. D) losing oxygen. E) all of the above

E) all of the above

The following reaction can be classified as what type(s) of reaction(s)? 2 Al(OH)3(aq) + 3 H2SO4(aq) Al2(SO4)3(s) + 6 H2O(l) A) precipitation B) acid-base neutralization C) redox reaction D) combustion E) both A and B

E) both A and B

Consider the reaction shown: 2 CO(g) + O2(g) CO2(g) + 135.2 kcal This reaction is ________ because the sign of H is ________.

E) exothermic; negative

Consider the reaction shown: C3H8 + 5 O2 3 CO2 + 4 H2O + 488 kcal We can say that this reaction is ________ and that the sign of H is ________.

E) exothermic; negative

All of the statements are true for spontaneous reactions except A) the value of G is less than zero. B) if the enthalpy change is unfavorable, they occur at a high temperature. C) the value of G is unaffected by a catalyst. D) they are said to be exergonic. E) the reaction rate is determined by the value of G.

E) the reaction rate is determined by the value of DELTA G.

The combination of ions most likely to produce a precipitate is

Fe3+ and OH-.

Which reaction is an example of a precipitation reaction?

FeCl3(aq) + 3 KOH(aq) Fe(OH)3(s) + 3 KCl(aq)

The formation of which one of the compounds below will act as the driving force for an acid-base reaction?

H20

Which reaction is an example of both a precipitation and a neutralization?

H2SO4(aq) + Ba(OH)2(aq) BaSO4(s) + 2 H2O(l)

Which statement best describes the way a catalyst works?

It decreases the value of Eact.

The combination of ions least likely to produce a precipitate is

Mg2+ and C2H3O2-.

The balanced equation for the reaction between aqueous ammonium sulfate and aqueous barium acetate is

NH4)2SO4(aq) + Ba(C2H3O2)2(aq) BaSO4(s) + 2 NH4C2H3O2(aq).

Which statement based on the mole concept is not correct? 3) A) One mole of methane, CH4, contains the same number of atoms as one mole of carbon dioxide, CO2. B) The number of atoms in one mole of platinum is the same as the number of atoms in one mole of uranium. C) The molar mass of a diatomic element is its atomic weight in grams times two. D) One mole of sodium chloride, NaCl, contains the same number of ions as one mole of calcium sulfate, CaSO4. E) One mole of bromine, Br2, contains the same number of molecules as one mole of propane, C3H8.

One mole of methane, CH4, contains the same number of atoms as one mole of carbon dioxide, CO2.

Which of the following statements can be assumed to be true about how reactions occur?

Reactant particles must collide with each other.

Which statement regarding balanced chemical equations is not true?

Subscripts may be changed to make an equation simpler to balance.

Consider the reaction shown and identify the statement that is not true. CaCO3(s) ---->825°C -----> CaO(s) + CO2(g)

Water must be present for this reaction to occur.

Based on the reaction shown, which statement is true? P4(s) + 10 Cl2(g) 4 PCl5(s) --> H = -435.2 kcal

When 1 mol P4(s) reacts, 435.2 kcal are released.

Which of the following states of matter should have the lowest entropy value?

a crystalline solid

Entropy can be defined as the

amount of disorder in a system.

Activation energy can best be described as the

difference in energy between reactants and the maximum energy.

In the reaction energy diagrams shown, reaction A is ________, and it occurs ________ reaction B.

endergonic; faster than

In the reaction energy diagrams shown, reaction B is ________, and it occurs ________ reaction B.

endergonic; faster than

Consider the reaction shown: 452 kcal + 4 PCl5(s) P4(s) + 10 Cl2(g) This reaction is ________ because the sign of H is ________.

endothermic; positive

The concept of free energy allows prediction of spontaneity of a process by considering the changes in ________ and ________ during the process.

enthalpy; entropy

Based on the reaction shown, which statement is true? 4 PCl3(l) --> P4(s) + 6 Cl2(g) H = 304.0 kcal

hen 1 mol P4(s) is produced, 304.0 kcal are consumed.

The function of a catalyst in a reaction system is to

increase the rate of the reaction.

Entropy is used to

indicate the disorder of a system.

Which of the following is not soluble in water?

iron(III) hydroxide

When a solution of iron(III) nitrate is mixed with a solution of sodium hydroxide, a rust colored precipitate forms. This precipitate is probably

iron(III) hydroxide.

The reaction 2 AgNO3(aq) + K2SO4(aq) 2 KNO3(aq) + Ag2SO4(s) is an example of a(an)

precipitation

A reaction that is spontaneous can be described as

proceeding without external influence once it has begun.

Reaction rates are determined by all of the following factors except the

spontaneity of the reaction.

The scientific principle which is the basis for balancing chemical equations is

the Law of Conservation of Mass.

When a reaction system is at equilibrium

the rates of the reaction in the forward and reverse directions are exactly equal.

In a balanced chemical equation

there are equal numbers of atoms on each side of the reaction arrow.

Consider the endothermic reaction: N2(g) + 2 H2(g) N2H4(l) The entropy change of this reaction is ________ and the enthalpy change is ________, so at a very high temperature, this reaction is probably ________.

unfavorable; unfavorable; nonspontaneous

All of the statements regarding redox reactions are true except

when a substance is oxidized its charge (or oxidation number) decreases.