11.1 – 11.2 Student Notes

States of Matter; Liquids and Solids

I. States of Matter

A. Comparison of Gases, Liquids, and Solids

1. Gases

2. Liquids

3. Solids

4. van der Waals equation

(P + n²a/V²)(V – nb) = nRT

a.

b.

B. Changes of State

1. Change of state – phase transition –

2. Phase Transitions

a. Melting –

b. Freezing –

c. Vaporization –

d. Sublimation –

e. Condensation –

3. Vapor Pressure

a. Def –

b. Process of becoming a vapor

c. Rate of condensing equals rate of vaporizing à

d.

e. Volatile –

4. Boiling Point and Melting Point

a. Boiling point –

b. When the vapor pressure equals the atmospheric pressure,

c. Freezing point –

d. Melting point –

e. Freezing point =

5. Heat of Phase Transition

a. When heat is added during a phase transition,

b. The length of each flat region is proportional

c. Heat of fusion (enthalpy of fusion) – ΔH_fus –

d. Heat of vaporization (enthalpy of vaporization) – ΔH_vap –

e. Melting -

Vaporizing –

f. Calculating the Heat Required for a Phase Change of a Given Mass of Substance

A particular refrigerator cools by evaporating liquefied dichlorodifluormethane, CCl₂F₂. How many kilograms of this liquid must be evaporated to freeze a tray of water at 0° C? The mass of the water is 525 g, the heat of fusion of ice is 6.01 kJ/mol, and the heat of vaporization of dichlorofluoromethan is 17.4 kJ/mol.

6. Clausisus – Clapeyron Equation: Relating Vapor Pressure and Liquid Temperature

Formula

a. Calculating the Vapor Pressure at a Given Temperature

Estimate the vapor pressure of water at 85° C. Note that the normal boiling point of water is 100° C and that its heat of vaporization is 40.7 kJ/mol.

b. Calculating the Heat of Vaporization from Vapor Pressures

Calculate the heat of vaporization of diethyl ether, C₄H₁₀O, form the following vapor pressures: 400 mm Hg at 18° C and 760 mm Hg at 35° C. (Each pressure value has three significant figures.)