Question 1

Consider the following reaction: 2Al(s) + 3Cl₂(g) → 2AlCl₃(s), ΔH = -1390.81 kJ A) Is the reaction exothermic or endothermic? B) Calculate the heat produced when 10.0 g of AlCl₃ forms. C) How many grams of Al are required to produce 1.00 kJ of energy?

Accepted Answer

The answer of Consider the following reaction: 2Al(s) + 3Cl₂(g) →...

Question 2

The heat combustion of acetylene, C₂H₂(g), at 25°C, is -1299 kJ/mol. At this temperature, ΔH°_f values for CO₂(g) and H₂O(l) are -393 and -286 kJ/mol, respectively. Calculate ΔH°_f for acetylene.

Accepted Answer

The combustion reaction for acetylene is: 2C₂H₂(g) + 5O₂(g) → 4CO₂(g) + 2H₂O(l). Using ΔH° = ΣΔH°f(products) - ΣΔH°f(reactants), we have: -1299 kJ/mol = [4(-393) + 2(-286)] - [2(ΔH°f(C₂H₂))]. Solving for ΔH°f(C₂H₂), we get 227 kJ/mol.

Question 3

Consider the following data: Use Hess's law to find the change in enthalpy at 25°C for the following equation: CaC₂(s) + 2H₂O(l) → C₂H₂(g) + Ca(OH)₂(aq)

Accepted Answer

The answer of Consider the following data:  
Use Hess's...

Question 4

Acetylene (C₂H₂) and butane (C₄H₁₀) are gaseous fuels. Determine the ratio of energy available from the combustion of a given volume of acetylene to butane at the same temperature and pressure using the following data: The change in enthalpy of combustion for C₂H₂(g) = -49.9 kJ/g.The change in enthalpy of combustion for C₄H₁₀ = -49.5 kJ/g.

Accepted Answer

The answer of Acetylene (C₂H₂) and butane (C₄H₁₀) are gaseous...

Question 5

The standard state of carbon as a free element is graphite. C₆₀ is an allotropic form of carbon belonging to a class of structures known as fullerenes. for C₆₀ should be

Accepted Answer

The answer of The standard state of carbon as a...

Question 6

For which of the following reaction(s) is the enthalpy change for the reaction not equal to ΔH°_f of the product? I. 2H(g) → H₂(g) II. H₂(g) + O₂(g) → H₂O₂(l) III. H₂O(l) + O(g) → H₂O₂(l)

Accepted Answer

For reaction I, the enthalpy change for the reaction is equal to the standard enthalpy of formation of H2 minus twice the standard enthalpy of formation of H atom, which is not equal to the standard enthalpy of formation of H₂, thus the enthalpy change for the reaction is not equal to ΔH°_f of the product. For reaction II and III, the enthalpy change for the reactions are equal to the sum of the standard enthalpies of formation of the products minus the sum of the standard enthalpies of formation of the reactants, which is equal to ΔH°_f of the product.

Question 7

The standard enthalpy change for the following reaction is -542 kJ: H₂(g) + F₂(g) → 2HF(g) Calculate the standard enthalpy of formation of hydrogen fluoride.

Accepted Answer

The standard enthalpy change given is for the formation of 2 moles of HF. To find the enthalpy of formation per mole, divide -542 kJ by 2, resulting in -271 kJ/mol.

Question 8

Which of the following statements is true for a monatomic ideal gas?

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The answer of Which of the following statements is true...

Question 9

Using the information below, calculate ΔH°_f for C₂H₅OH(l).C₂H₅OH(l) + 3O₂(g) → 2CO₂(g) + 3H₂O(l), ΔH° = -1367 kJ ΔH°_f for CO₂(g) = -393.5 kJ/mol ΔH°_f for H₂O(l) = -286 kJ/mol

Accepted Answer

To find ΔH°f for C2H5OH(l), use the equation for the reaction's enthalpy change: ΔH° = ΣΔH°f(products) - ΣΔH°f(reactants). For the products, 2 mol of CO2(g) and 3 mol of H2O(l) contribute -393.5 kJ/mol * 2 + -286 kJ/mol * 3 = -1645 kJ. The only reactant with an unknown ΔH°f is C2H5OH(l), and O2(g) is a standard state element with ΔH°f = 0. Rearranging the equation gives ΔH°f(C2H5OH) = ΣΔH°f(products) - ΔH° - ΣΔH°f(reactants excluding C2H5OH). Substituting the given values yields ΔH°f(C2H5OH) = -1645 kJ - (-1367 kJ) = -278 kJ/mol.

Question 10

Consider the following standard heats of formation: P₄O₁₀(s) = -3110 kJ/mol H₂O(l) = -286 kJ/mol H₃PO₄(s) = -1279 kJ/mol Calculate the change in enthalpy for the following process: P₄O₁₀(s) + 6H₂O(l) → 4H₃PO₄(s)

Accepted Answer

The answer of Consider the following standard heats of formation: P₄O₁₀(s)...

Question 11

The heat of formation of Fe₂O₃(s) is -826 kJ/mol. Calculate the heat of the reaction 4Fe(s) + 3O₂(g) → 2Fe₂O₃(s) when a 15.2 g sample of iron is reacted.

Accepted Answer

The answer of The heat of formation of Fe₂O₃(s) is...

Question 12

The combustion of methanol takes place according to the reaction 2CH₃OH(l) + 3O₂(g) → 2CO₂(g) + 4H₂O(l) Calculate ΔH for the combustion of 1 mol of methanol under standard conditions. Use the following standard enthalpies of formation:

Accepted Answer

The answer of The combustion of methanol takes place according...

Question 13

Using the following data, calculate the standard heat of formation of ICl(g) in kJ/mol.

Accepted Answer

The answer of Using the following data, calculate the standard...

Question 14

Standard enthalpies of formation are tabulated on a

Accepted Answer

Standard enthalpies of formation are defined as the change in enthalpy when one mole of a compound is formed from its constituent elements in their standard states. Therefore, the best choice for tabulating these values is on a mole basis.

Question 15

For the reaction AgI(s) + (1/2)Br₂(g) → AgBr(s) + (1/2)I₂(s), ΔH° = -54.0 kJ ΔH°_f for AgBr(s) = -100.4 kJ/mol ΔH°_f for Br₂(g) = +30.9 kJ/mol The value of ΔH°_f for AgI(s) is

Accepted Answer

Using Hess's Law, we can add the enthalpies of formation of the products and subtract the enthalpies of formation of the reactants. ΔH° = ΣΔH°_f(products) - ΣΔH°_f(reactants) We are given the values for ΔH°_f for AgBr(s) and Br₂(g), but not for AgI(s). However, we know that AgI(s) is a reactant in the equation, so we can use algebra to solve for its enthalpy of formation: ΔH°_f for AgI(s) = ΣΔH°_f(reactants) - ΣΔH°_f(products) ΔH°_f for AgI(s) = [-54.0 kJ/mol] - [(1/2)(-100.4 kJ/mol)] - [(1/2)(30.9 kJ/mol)] ΔH°_f for AgI(s) = -61.8 kJ/mol Therefore, the best choice is C, with an explanation that we can use Hess's Law and the given enthalpies of formation to solve for ΔH°_f for AgI(s).

Question 16

Given the following two reactions at 298 K and 1 atm, which of the statements is true?

Accepted Answer

The answer of Given the following two reactions at 298...

Question 17

Using the information below, calculate ΔH°_f for PbO(s).PbO(s) + CO(g) → Pb(s) + CO₂(g), ΔH° = -131.4 kJ ΔH°_f for CO₂(g) = -393.5 kJ/mol ΔH°_f for CO(g) = -110.5 kJ/mol

Accepted Answer

To find ΔH°_f for PbO(s), use the equation: ΔH° = ΔH°_f(products) - ΔH°_f(reactants). Rearrange to find ΔH°_f(PbO): ΔH°_f(PbO) = ΔH°_f(CO₂) + ΔH°_f(Pb) - ΔH°_f(CO) - ΔH°. Substituting the values: ΔH°_f(PbO) = (-393.5) + 0 - (-110.5) - (-131.4) = -151.6 kJ/mol.

Question 18

The enthalpy of formation of an element in its standard state is

Accepted Answer

The enthalpy of formation of an element in its standard state is defined as the enthalpy change that accompanies the formation of one mole of the substance from its elements in their standard states, and since the element is already in its standard state, no formation is taking place, and therefore the enthalpy of formation is zero.

Question 19

Specific heat capacities are tabulated on a

Accepted Answer

The answer of Specific heat capacities are tabulated on a
...

Question 20

Choose the correct equation for the standard enthalpy of formation of CO(g), where ΔH°_f for CO = -110.5 kJ/mol.

Accepted Answer

The answer of Choose the correct equation for the standard...

Quiz 9: Energy, Enthalpy, and Thermochemistry

Consider the following reaction: 2Al(s) + 3Cl₂(g) → 2AlCl₃(s), ΔH = -1390.81 kJ A) Is the reaction exothermic or endothermic? B) Calculate the heat produced when 10.0 g of AlCl₃ forms. C) How many grams of Al are required to produce 1.00 kJ of energy?

The heat combustion of acetylene, C₂H₂(g) , at 25°C, is -1299 kJ/mol. At this temperature, ΔH°_f values for CO₂(g) and H₂O(l) are -393 and -286 kJ/mol, respectively. Calculate ΔH°_f for acetylene.

Consider the following data: Use Hess's law to find the change in enthalpy at 25°C for the following equation: CaC₂(s) + 2H₂O(l) → C₂H₂(g) + Ca(OH)₂(aq)

The standard state of carbon as a free element is graphite. C₆₀ is an allotropic form of carbon belonging to a class of structures known as fullerenes. for C₆₀ should be

For which of the following reaction(s) is the enthalpy change for the reaction not equal to ΔH°_f of the product? I. 2H(g) → H₂(g) II. H₂(g) + O₂(g) → H₂O₂(l) III. H₂O(l) + O(g) → H₂O₂(l)

The standard enthalpy change for the following reaction is -542 kJ: H₂(g) + F₂(g) → 2HF(g) Calculate the standard enthalpy of formation of hydrogen fluoride.

Which of the following statements is true for a monatomic ideal gas?

Using the information below, calculate ΔH°_f for C₂H₅OH(l) .C₂H₅OH(l) + 3O₂(g) → 2CO₂(g) + 3H₂O(l) , ΔH° = -1367 kJ ΔH°_f for CO₂(g) = -393.5 kJ/mol ΔH°_f for H₂O(l) = -286 kJ/mol

Consider the following standard heats of formation: P₄O₁₀(s) = -3110 kJ/mol H₂O(l) = -286 kJ/mol H₃PO₄(s) = -1279 kJ/mol Calculate the change in enthalpy for the following process: P₄O₁₀(s) + 6H₂O(l) → 4H₃PO₄(s)

The heat of formation of Fe₂O₃(s) is -826 kJ/mol. Calculate the heat of the reaction 4Fe(s) + 3O₂(g) → 2Fe₂O₃(s) when a 15.2 g sample of iron is reacted.

The combustion of methanol takes place according to the reaction 2CH₃OH(l) + 3O₂(g) → 2CO₂(g) + 4H₂O(l) Calculate ΔH for the combustion of 1 mol of methanol under standard conditions. Use the following standard enthalpies of formation:

Using the following data, calculate the standard heat of formation of ICl(g) in kJ/mol.

Standard enthalpies of formation are tabulated on a

For the reaction AgI(s) + (1/2) Br₂(g) → AgBr(s) + (1/2) I₂(s) , ΔH° = -54.0 kJ ΔH°_f for AgBr(s) = -100.4 kJ/mol ΔH°_f for Br₂(g) = +30.9 kJ/mol The value of ΔH°_f for AgI(s) is

Given the following two reactions at 298 K and 1 atm, which of the statements is true?

Using the information below, calculate ΔH°_f for PbO(s) .PbO(s) + CO(g) → Pb(s) + CO₂(g) , ΔH° = -131.4 kJ ΔH°_f for CO₂(g) = -393.5 kJ/mol ΔH°_f for CO(g) = -110.5 kJ/mol

The enthalpy of formation of an element in its standard state is

Specific heat capacities are tabulated on a

Choose the correct equation for the standard enthalpy of formation of CO(g) , where ΔH°_f for CO = -110.5 kJ/mol.

Quiz 9: Energy, Enthalpy, and Thermochemistry

Consider the following reaction: 2Al(s) + 3Cl2(g) → 2AlCl3(s), ΔH = -1390.81 kJ A) Is the reaction exothermic or endothermic? B) Calculate the heat produced when 10.0 g of AlCl3 forms. C) How many grams of Al are required to produce 1.00 kJ of energy?

The heat combustion of acetylene, C2H2(g) , at 25°C, is -1299 kJ/mol. At this temperature, ΔH°f values for CO2(g) and H2O(l) are -393 and -286 kJ/mol, respectively. Calculate ΔH°f for acetylene.

Consider the following data: Use Hess's law to find the change in enthalpy at 25°C for the following equation: CaC2(s) + 2H2O(l) → C2H2(g) + Ca(OH)2(aq)

The standard state of carbon as a free element is graphite. C60 is an allotropic form of carbon belonging to a class of structures known as fullerenes. for C60 should be

For which of the following reaction(s) is the enthalpy change for the reaction not equal to ΔH°f of the product? I. 2H(g) → H2(g) II. H2(g) + O2(g) → H2O2(l) III. H2O(l) + O(g) → H2O2(l)

The standard enthalpy change for the following reaction is -542 kJ: H2(g) + F2(g) → 2HF(g) Calculate the standard enthalpy of formation of hydrogen fluoride.

Which of the following statements is true for a monatomic ideal gas?

Using the information below, calculate ΔH°f for C2H5OH(l) .C2H5OH(l) + 3O2(g) → 2CO2(g) + 3H2O(l) , ΔH° = -1367 kJ ΔH°f for CO2(g) = -393.5 kJ/mol ΔH°f for H2O(l) = -286 kJ/mol

Consider the following standard heats of formation: P4O10(s) = -3110 kJ/mol H2O(l) = -286 kJ/mol H3PO4(s) = -1279 kJ/mol Calculate the change in enthalpy for the following process: P4O10(s) + 6H2O(l) → 4H3PO4(s)

The heat of formation of Fe2O3(s) is -826 kJ/mol. Calculate the heat of the reaction 4Fe(s) + 3O2(g) → 2Fe2O3(s) when a 15.2 g sample of iron is reacted.

The combustion of methanol takes place according to the reaction 2CH3OH(l) + 3O2(g) → 2CO2(g) + 4H2O(l) Calculate ΔH for the combustion of 1 mol of methanol under standard conditions. Use the following standard enthalpies of formation:

Using the following data, calculate the standard heat of formation of ICl(g) in kJ/mol.

Standard enthalpies of formation are tabulated on a

For the reaction AgI(s) + (1/2) Br2(g) → AgBr(s) + (1/2) I2(s) , ΔH° = -54.0 kJ ΔH°f for AgBr(s) = -100.4 kJ/mol ΔH°f for Br2(g) = +30.9 kJ/mol The value of ΔH°f for AgI(s) is

Given the following two reactions at 298 K and 1 atm, which of the statements is true?

Using the information below, calculate ΔH°f for PbO(s) .PbO(s) + CO(g) → Pb(s) + CO2(g) , ΔH° = -131.4 kJ ΔH°f for CO2(g) = -393.5 kJ/mol ΔH°f for CO(g) = -110.5 kJ/mol

The enthalpy of formation of an element in its standard state is

Specific heat capacities are tabulated on a

Choose the correct equation for the standard enthalpy of formation of CO(g) , where ΔH°f for CO = -110.5 kJ/mol.

Consider the following reaction: 2Al(s) + 3Cl₂(g) → 2AlCl₃(s), ΔH = -1390.81 kJ A) Is the reaction exothermic or endothermic? B) Calculate the heat produced when 10.0 g of AlCl₃ forms. C) How many grams of Al are required to produce 1.00 kJ of energy?

The heat combustion of acetylene, C₂H₂(g) , at 25°C, is -1299 kJ/mol. At this temperature, ΔH°_f values for CO₂(g) and H₂O(l) are -393 and -286 kJ/mol, respectively. Calculate ΔH°_f for acetylene.

Consider the following data: Use Hess's law to find the change in enthalpy at 25°C for the following equation: CaC₂(s) + 2H₂O(l) → C₂H₂(g) + Ca(OH)₂(aq)

The standard state of carbon as a free element is graphite. C₆₀ is an allotropic form of carbon belonging to a class of structures known as fullerenes. for C₆₀ should be

For which of the following reaction(s) is the enthalpy change for the reaction not equal to ΔH°_f of the product? I. 2H(g) → H₂(g) II. H₂(g) + O₂(g) → H₂O₂(l) III. H₂O(l) + O(g) → H₂O₂(l)

The standard enthalpy change for the following reaction is -542 kJ: H₂(g) + F₂(g) → 2HF(g) Calculate the standard enthalpy of formation of hydrogen fluoride.

Using the information below, calculate ΔH°_f for C₂H₅OH(l) .C₂H₅OH(l) + 3O₂(g) → 2CO₂(g) + 3H₂O(l) , ΔH° = -1367 kJ ΔH°_f for CO₂(g) = -393.5 kJ/mol ΔH°_f for H₂O(l) = -286 kJ/mol

Consider the following standard heats of formation: P₄O₁₀(s) = -3110 kJ/mol H₂O(l) = -286 kJ/mol H₃PO₄(s) = -1279 kJ/mol Calculate the change in enthalpy for the following process: P₄O₁₀(s) + 6H₂O(l) → 4H₃PO₄(s)

The heat of formation of Fe₂O₃(s) is -826 kJ/mol. Calculate the heat of the reaction 4Fe(s) + 3O₂(g) → 2Fe₂O₃(s) when a 15.2 g sample of iron is reacted.

The combustion of methanol takes place according to the reaction 2CH₃OH(l) + 3O₂(g) → 2CO₂(g) + 4H₂O(l) Calculate ΔH for the combustion of 1 mol of methanol under standard conditions. Use the following standard enthalpies of formation:

For the reaction AgI(s) + (1/2) Br₂(g) → AgBr(s) + (1/2) I₂(s) , ΔH° = -54.0 kJ ΔH°_f for AgBr(s) = -100.4 kJ/mol ΔH°_f for Br₂(g) = +30.9 kJ/mol The value of ΔH°_f for AgI(s) is

Using the information below, calculate ΔH°_f for PbO(s) .PbO(s) + CO(g) → Pb(s) + CO₂(g) , ΔH° = -131.4 kJ ΔH°_f for CO₂(g) = -393.5 kJ/mol ΔH°_f for CO(g) = -110.5 kJ/mol

Choose the correct equation for the standard enthalpy of formation of CO(g) , where ΔH°_f for CO = -110.5 kJ/mol.