Bond enthalpy, gas properties reading

Select all of the statements that correctly describe bond enthalpies.

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

In which phase do the individual particles (atoms or molecules) remain much farther apart and have the ability to move freely?

Gas

Select all the statements that correctly describe the properties of gases.

Gases are much more compressible than liquids or solids. Gases have relatively low densities. Temperature changes have a large effect on the volume of a gas.

Select all the statements that correctly describe the arrangement of individual particles in the three physical states of matter. Relate these particulate views to the observable properties of matter.

Gases occupy the entire volume of the container. The particles in a gas move quite freely. The particles in a solid occupy fixed positions. Liquids take the shape of the container.

Select all the diatomic elements that exist as gases at room temperature.

Hydrogen gas Halogens such as F2 and Cl2 Nitrogen and oxygen

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

Which molecules are gases at room temperature?

NH3 CO2 HCl

Which of the following factors determine whether a given substance exists as a solid, liquid, or gas? Select all that apply.

Pressure Temperature

Select the statement that correctly explains the source of the energy change in a chemical reaction.

The main contribution to ΔH is the difference in the bond energies of reactants and products.

The particles in a gas have a _____ distance between them than the particles of a liquid or a solid and their movement is random. Gas particles therefore move _____ freely than the particles of solids or liquids.

greater, more

Gases tend to have _____ densities than either liquids or solids, and their _____ change greatly with changes in temperature or pressure.

lower, volumes

The enthalpy of a reaction may be calculated using average bond enthalpies using an equation in which the energy _____ bonds form is subtracted from the energy _____ break bonds.

released when; required to

Select the answer that best completes the following sentence:The bond enthalpy is ______.

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

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

x + y - 2z

Which of the following options correctly describe the procedure used to calculate ΔH for a reaction using bond energies? Select all that apply.

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

Select the correct form of the equation to find the enthalpy of a reaction from average bond enthalpies.

ΔH° = ΣBE(reactants) - ΣBE(products)