Reading Assignment Chapter 10.5 - 10.8

Calculate the standard enthalpy change for the reaction SiO2 (s) + 4HF (g) → SiF4 (g) + 2H2O (l) given the information in the table below. Compound ΔH°f (kJ/mol) HF (g) -273.0 H2O (l) -285.8 SiF4 (g) -1614.9 SiO2 (s) -910.9 -4189.4 kJ +183.6 kJ -2005.4 kJ -183.6 kJ

-183.6 kJ

Which of the following reactions is associated with the standard enthalpy of formation of NH3 (g)? N (g) + 3H (g) → NH3 (g) 1212N2 (g) + 3232H2 (g) → NH3 (g) N2 (g) + 3H2 (g) → 2NH3 (g)

1212N2 (g) + 3232H2 (g) → NH3 (g)

Calculate ΔH°rxn for the reaction A + 2B → 2C using the ΔH°f values given below. Compound ΔH°f A a B b C c (a) + 2(b) - 2(c) (c) - (a) - (b) (a) + (b) - (c) 2(c) - (a) - 2(b)

2(c) - (a) - 2(b)

The standard enthalpy of formation of a compound is the enthalpy change associated with the reaction that generates mole(s) of that compound from its component when all of the substances are under conditions.

Blank 1: 1, one, or 1.0 Blank 2: elements Blank 3: standard, standard-state, or standard state

For a reaction that proceeds through a series of steps, ΔHoverall = ΔH1 + ΔH2 + ΔH3 + .... This is a restatement of law.

Blank 1: Hess's, Hess', or Hess

By definition, the standard enthalpy of formation of a pure in its standard state is equal to 0 kJ/mol.

Blank 1: element

The standard enthalpy of is the change in enthalpy associated with the chemical reaction that generates 1 mole of a substance from its constituent in their standard states.

Blank 1: formation Blank 2: elements

The amount of energy required to separate 1 mole of ions in a crystalline solid into separate gaseous ions is called energy. This energy is a measure of the total strength of the bonds in the solid.

Blank 1: lattice Blank 2: ionic

An element that is in its most stable form at ordinary atmospheric pressure is in its state (usually signified by a degree sign).

Blank 1: standard

Select all of the statements that correctly describe bond enthalpies. Bond enthalpies are always positive. Bond enthalpies are always negative. Bond enthalpies are the energy generated when a bond is broken. Bond enthalpies can be positive or negative Bond enthalpies represent the energy required to break bonds.

Bond enthalpies are always positive. Bond enthalpies represent the energy required to break bonds.

Which of the following reactions would have an enthalpy change equal to ΔHf°? Select all that apply. C(graphite) + O2 (g) → CO2 (g) CH4 (g) → C(graphite) + 2H2 (g) 3O2 (g) → 2O3 (l) Fe (s) + 3232Cl2 (g) → FeCl3 (s) Hg (s) + S (s) → HgS (s)

C(graphite) + O2 (g) → CO2 (g) Fe (s) + 3232Cl2 (g) → FeCl3 (s)

The formation of an ionic bond involves a number of different processes. If we consider the separate electron transfer processes involved in the formation of sodium chloride, which individual steps would require an input of energy? The overall process is represented by the equation shown below. Select all that apply. 2Na (s) + Cl2 (g) → 2NaCl (s) Attraction of Na+ and Cl- to form NaCl Conversion of Na (s) → Na (g) Dissociation of Cl2 to form 2Cl The addition of an electron to each Cl atom Removal of an electron from Na

Conversion of Na (s) → Na (g) Dissociation of Cl2 to form 2Cl Removal of an electron from Na

Which of the following reactions would have an enthalpy change equal to ΔHf°? Select all that apply. Fe (s) + 3232Cl2 (g) → FeCl3 (s) Hg (s) + S (s) → HgS (s) 3O2 (g) → 2O3 (l) C(graphite) + O2 (g) → CO2 (g) CH4 (g) → C(graphite) + 2H2 (g)

Fe (s) + 3232Cl2 (g) → FeCl3 (s) C(graphite) + O2 (g) → CO2 (g)

Which of the following substances would have a standard enthalpy of formation equal to 0 kJ/mol? Select all that apply. Br2 (g) H2 (g) O3 (g) Ar (g) Hg (l) C (diamond)

H2 (g) Ar (g) Hg (l)

Ionic compounds differ significantly from molecular compounds. Select the all of the features that are typical of ionic compounds. Ionic substances tend to be gases at room temperature. Ionic compounds have high melting points. Ionic compounds vaporize easily. Ionic substances form electrically conductive solutions when dissolved. Ionic substances tend to be solids at room temperature.

Ionic compounds have high melting points. Ionic substances form electrically conductive solutions when dissolved. Ionic substances tend to be solids at room temperature.

Select the statements that correctly describe lattice energy. Lattice energy is the energy required to arrange the ions of an ionic solid in a regular lattice. Lattice energy is a measure of the total strength of interaction between ions in the solid. Lattice energy decreases as the attraction between the ions increases. Lattice energy is the energy required to force gaseous ions together to form 1 mol of an ionic solid. Lattice energy is the energy required to separate 1 mol of an ionic solid into gaseous ions.

Lattice energy is a measure of the total strength of interaction between ions in the solid. Lattice energy is the energy required to separate 1 mol of an ionic solid into gaseous ions.

Generate the equation A + 2B → 2D from a combination of the reactions provided. Reaction 1: A + 2B → 2C Reaction 2: C → D How must reactions 1 and 2 be combined to sum to the overall reaction? Reaction 1 + 2(Reaction 2) Reaction 1 + Reaction 2 Reaction 1 + (-Reaction 2) 2(Reaction 1) + Reaction 2

Reaction 1 + 2(Reaction 2)

Which of the following relationships are correct regarding forces of attraction in molecular and ionic species? The attractive forces between ions tend to be stronger than the attractive forces between adjacent molecules. The weak forces between molecules causes them to be unstable. Weak forces between molecules result in gaseous, liquid, or low-melting covalent compounds. The high bond enthalpies in molecular compounds causes them to form strong, brittle solids.

The attractive forces between ions tend to be stronger than the attractive forces between adjacent molecules. Weak forces between molecules result in gaseous, liquid, or low-melting covalent compounds.

The formation of an ionic compound involves the transfer of electrons. The removal of one or more electrons from a metal is a process that _____ energy, whereas the addition of one or more electrons to a nonmetal _____ energy. releases; absorbs absorbs; releases

absorbs; releases

An element that is in its most stable form at ordinary atmospheric pressure is in its ______ state (usually signified by a degree sign). 25 oC formation Hess' standard

standard

Hess's law states that the enthalpy change for an overall process (which can be broken into multiple steps) will be equal to the _____ of the enthalpy changes of its individual steps. product sum difference

sum

Select the answer that best completes the following sentence:The bond enthalpy is ______. the enthalpy change associated with forming a particular bond in one mole of gaseous molecules the total enthalpy change when 1 mole of gaseous molecules is formed from its elements the enthalpy change associated with breaking a particular bond in one mole of gaseous molecules

the enthalpy change associated with breaking a particular bond in one mole of gaseous molecules

Select the answer that best completes the following sentence:The bond enthalpy is ______. the total enthalpy change when 1 mole of gaseous molecules is formed from its elements the enthalpy change associated with breaking a particular bond in one mole of gaseous molecules the enthalpy change associated with forming a particular bond in one mole of gaseous molecules

the enthalpy change associated with breaking a particular bond in one mole of gaseous molecules

Select the answer that best completes the following sentence. The standard enthalpy of formation, ΔHfo, is ______. the enthalpy change when one mole of a substance breaks down into its constiuent elements the enthalpy change when one mole of a substance is formed from standardized substances the enthalpy change when one mole of a substance is converted to its standard state the enthalpy change when one mole of a substance is formed from its constituent elements in their standard states

the enthalpy change when one mole of a substance is formed from its constituent elements in their standard states

Consider the following reactions: A → 2B; ΔH = x kJ B → C; ΔH = y kJ What would be the enthalpy change associated with the reaction below? A → 2C x - y x + 2y x + y 2x + y

x + 2y

For the hypothetical reaction below, select the expression that would be equal to the enthalpy of the reaction. A-A + B-B → 2 A-B Bond Enthalpies: A-A = x B-B = y A-B = z z - x - y x + y - z x + y - 2z 2 z - x - y

x + y - 2z

CO (g) can be produced by the reaction of coal with steam, as shown by the balanced equation: H2O (g) + C (s) → CO (g) + H2 (g). Which of the following options correctly reflect the steps required to calculate ΔH for this reaction, given the information shown below? Select all that apply. Reaction 1: H2 (g) + 1212O2 (g) → H2O (g); ΔH = -242.0 kJ Reaction 2: 2CO (g) → 2C (s) + O2 (g); ΔH = +221.0 kJ ΔH = -131.5 kJ ΔH = -21 kJ ΔH = +131.5 kJ Reaction 1 must be divided by 2. Reaction 2 must be reversed and divided by 2.

ΔH = +131.5 kJ Reaction 2 must be reversed and divided by 2.

Which of the following options correctly describe the procedure used to calculate ΔH for a reaction using bond energies? Select all that apply. ΔHbonds formed is always endothermic. ΔH for the reaction is given by (sum of ΔHbonds formed) + (sum of ΔHbonds broken) The sum ΔHbonds broken is given a positive value. ΔH is obtained by adding together the absolute values of the bond energies for all bonds broken and formed.

ΔH for the reaction is given by (sum of ΔHbonds formed) + (sum of ΔHbonds broken) The sum ΔHbonds broken is given a positive value.

Consider the reaction shown. Select all the statements that correctly apply to the calculation of ΔH for this reaction using the bond energies provided. In this reaction, two C-C bonds are broken. ΔH for this reaction is equal to -168 kJ/mol. ΔH for this reaction is equal to +168 kJ/mol. In this reaction, two C-Cl bonds are formed.

ΔH for this reaction is equal to -168 kJ/mol. In this reaction, two C-Cl bonds are formed.

Select the correct form of the equation to find the enthalpy of a reaction from average bond enthalpies. ΔH° = ΣBE(products) - ΣBE(reactants) ΔH° = ΣBE(reactants) - ΣBE(products) ΔH° = ΣBE(reactants) × ΣBE(products) ΔH° = ΣBE(products)ΣBE(reactants)

ΔH° = ΣBE(reactants) - ΣBE(products)