Question

1) What type of intermolecular forces must be overcome in converting each of the following from a liquid to a gas? (circle all that apply) (a) CO2 dispersion dipole-dipole hydrogen bonding ion-dipole (b) NH3 dispersion dipole-dipole hydrogen bonding ion-dipole (c) CHCl3 dispersion dipole-dipole hydrogen bonding ion-dipole (d) CF4 dispersion dipole-dipole hydrogen bonding ion-dipole 2) What is the total quantity of heat required to convert 0.45 moles of ice from –7.0 °C to steam at 108.0 °C? ΔHfus = 334Jg ΔHvap = 2260Jg Cice(s) = 2.09Jg⋅°C Cwater(l) = 4.18Jg⋅°C Csteam(g) = 2.03Jg⋅°C

Answer 1

1.   

(a) CO2 =   dispersion forces.

(b) NH3 =   hydrogen bonding

(c) CHCl3 = dipole-dipole forces.

(d) CF4 = dispersion forces.

2.   Heat required = mice*s*DT + w*DHfus + mwater*s*DT + w*DHvap + msteam*s*DT

      mass of ice = 0.45*18 = 8.1 grams

                       = 8.1*2.09*(0--7) +8.1*334 + 8.1*4.18*(100-0)+8.1*2260+8.1*2.03*(108-100)

                   = 24647.25 joule.

                 = 24.647 kj