7. ldenity the strongest intermolecuarforcepresent n each pure sudstance and ine

ID: 588023 • Letter: 7

Question

7. ldenity the strongest intermolecuarforcepresent n each pure sudstance and ineach miature and weite your answer in the table below: LiNO3 NHs CH4 CH3OH HCI 8. Determine the sign of AH in each process below. Identify them as exothermic or endothermic. a. Ice melts in a warm room b. A gas is cooled at constant pressure. c. A mixture of gases undergoes a chemical reaction that releases heat into the lab room. 9. Which substance has the higher boiling point? Explain! CH3CH2OH or CH3CH2CH3 NO or N2 HF or HC 10. How much heat energy (in kJ) is needed to vaporize 36 g of liquid water at 100°C?

Explanation / Answer

7) Note the strongest intermolecular forces present in each of the pure substance below.

LiNO3: electrostatic force of attraction and repulsion between ions (LiNO3 is an ionic compound)

NH3: covalent compound; hydrogen bonding (dispersion forces and dipole-dipole forces are also present; however, hydrogen bonding between adjacent NH3 molecules is the major force)

CH4: covalent compound; dispersion forces

CH3OH: hydrogen bonding (dispersion forces and dipole-dipole forces are also present; however, hydrogen bonding between adjacent CH3OH molecules is the major force)

C2H6: dispersion forces

HCl: dipole-dipole forces (HCl is a molecular compound)

Next, fill up the chart as below.

LiNO3

NH3

CH4

CH3OH

Ion-dipole forces (LiNO3 is ionized into ions; CH3OH, being a dipole, interacts via ion-dipole interactions)

Hydrogen bonding (both the molecules are capable of forming hydrogen bonds)

Dispersion forces (CH3OH is polar while CH4 is non-polar)

C2H6

Dispersion forces and Electrostatic forces (infact, no intermolecular force can bring the two together; C2H6 has dispersion forces while LiNO3 has electrostatic forces)

Dispersion forces (NH3 is polar while C2H6 is non-polar)

Dispersion forces (both the molecules are non-polar)

HCl

Ion-dipole forces (LiNO3 is ionized into ions; HCl, being a dipole, interacts via ion-dipole interactions)

Hydrogen bonding (NH3 can form hydrogen bonds)

Dispersion forces (HCl is polar while CH4 is non-polar)