Chem 1075 Chapter 13 Liquids and Solids Lecture Outline

Transcription

1 Chem 1075 Chapter 13 Liquids and Solids Lecture Outline Slide 2-3 Properties of Liquids Unlike gases, liquids respond dramatically to temperature and pressure changes. We can study the liquid state and make 5 general observations. 1. Liquids have a, but a. Liquids take the shape of their 2. Liquids usually readily. However, not all liquids flow at the. 3. Liquids do not or significantly The volume of a liquid varies as the temperature and pressure change. 4. Liquids have a compared to gases. Liquids are about more dense than gases. 5. Liquids that are soluble mix. Liquids than gases but eventually will form a homogeneous mixture. Slide 4 Intermolecular Bond Concept An intermolecular bond is an attraction molecules, whereas intramolecular bonds are between atoms a molecule. Some properties of liquids, such as vapor pressure, viscosity, and surface tension, are determined by the strength of attraction between molecules. Intermolecular bonds are than intramolecular bonds. Slide 5 Intermolecular Bonds Recall, that a molecule has positive and negative charges concentrated in different regions due to of electrons in bonds. This uneven distribution of electrons in a molecule is called a. Intermolecular attractions result from or dipoles in molecules. There are three intermolecular forces: Slide 6 Dispersion Forces Dispersion forces, or London forces, are the result of. Electrons are constantly and a region may become temporarily and slightly while another region becomes slightly negative. This creates a temporary dipole and two molecules with temporary dipoles are to each other.

2 Slide 7 Dispersion Forces Continued Dispersion forces are the intermolecular force. Dispersion forces are present in molecules. The of the dispersion forces in a molecule is related to the in the molecule: The in a molecule, the the dispersion forces. Slide 8 Dipole Forces Polar molecules have a dipole. The oppositely charged ends of polar molecules are attracted to each other, this is the. The strength of a dipole force is typically of a covalent bond s strength. Dipole forces are than dispersion forces. Slide 9 Hydrogen Bonds Hydrogen bonds are a special type of dipole attraction. Hydrogen bonds are present when a molecule has an,, or bond. Hydrogen bonds are especially important in water and living organisms. Slide 10 Physical Properties of Liquids There are 4 physical properties of liquids that we can relate to the intermolecular attractions present in the molecules: Slide 11 Vapor Pressure At the of a liquid, some molecules gain enough energy to the intermolecular attractions of neighboring molecules and enter the. This is. The process is condensation. When the rates of evaporation and condensation are equal, the pressure exerted by the gas molecules above a liquid is called the.

3 Slide 12 Vapor Pressure Continued The the intermolecular forces between the molecules in the liquid, the molecules escape into the gas phase. As the between molecules, vapor pressure. Slide 13 Vapor Pressure Comparison Lets compare water and ether. Water has intermolecular attractions and ether has only intermolecular attractions. At 0 C, has a significant vapor pressure. At 35 C, ether has a vapor pressure and water. Slide 14 Vapor Pressure vs. Temperature As the temperature the vapor pressure of a liquid. Again, the the intermolecular attractions, the the vapor pressure at a given temperature.

4 Slide 15 Boiling Point The normal boiling point of a substance is the temperature where the vapor pressure is to the standard atmospheric pressure. As we saw in the previous graph, the the intermolecular attractions, the the boiling point of the liquid. A liquid with a boiling point has a vapor pressure. Slide 16 Viscosity The viscosity of a liquid is a liquid s. Viscosity is the result of an between molecules. The the intermolecular forces, the the viscosity. Slide 17 Surface Tension The between molecules at the of a liquid is called surface tension. For an object to sink in a liquid, it must first break through the surface. The the intermolecular attractions, the the surface tension of a liquid. Slide Properties of Solids Unlike gases, solids do not respond dramatically to temperature and pressure changes. We can study the solid state and make 5 general observations. 1. Solids have a shape and volume. Unlike liquids, solids are 2. Solids are either or. Crystalline solids contain particles in a regular, repeating. 3. Solids compress or expand to any degree Assuming no change in physical state, temperature and pressure have a on the volume of a solid. 4. Solids have a slightly density than their corresponding liquid One important is ; ice is less dense than liquid water. 5. Solids by diffusion The particles are to diffuse in a solid heterogeneous mixture.

5 Slide 20 Crystalline Solids There are three types of crystalline solids examples of which are shown below: a) b) c) Slide 21 Ionic Solids A crystalline is composed of positive and negative ions arranged in a pattern. In table salt, NaCl, sodium ions and chloride ions are arranged in a regular three-dimensional structure referred to as a crystal lattice. Other ionic compounds will have different crystal lattices. Slide 22 Molecular Solids A crystalline has arranged in a particular conformation. In water, H 2 O, the molecules are arranged in a regular three-dimensional structure. Other examples of crystalline molecular solids are table sugar, C 12 H 22 O 11, and sulfur, S 8. Slide 23 Metallic Solids A crystalline is composed of arranged in a definite pattern. A metallic crystal is made up of surrounded by. Metals are good conductors of electricity because electrons are about the crystal. This is referred to as the. Slide 24 General Properties of Solids Table 13.4 in Text Type of Solid General Properties Examples IONIC MOLECULAR METALLIC

6 Slide 25 Structure of Water Lets start with the electron dot formula for water: Water has a molecular shape and the bond angle is Water is a molecule that exhibits strong. Slide 26 Properties of Ice Water is a one of the few substances that is as a solid than as a liquid. As water freezes, the hydrogen bonds organize the water molecules into a three-dimensional structure where the molecules are than in the liquid. Liquid water has a density of 1.00 g/ml while ice has a density of g/ml. Slide 27 Physical Properties of Water Water has unusually melting and boiling points, especially compared to the other hydrogen compounds of Group IVA/16. This is due to, which is present but in H 2 S, H 2 Se, or H 2 Te.