Define a Solution Summary Activity Read pp. 266 – 268 Define the following terms: solution, homogeneous mixtures, solute, solvent, alloy, and aqueous solutions How are solutions classified? Utilize p. 266 Table 1 for examples What are some properties of aqueous solutions? Provide key terms, definitions and examples of each. Assigned Questions: p. 269 Practice UC #1, 2, 3, 4, 5, 6, 7 1

Define a Solution Summary Activity Read pp. 266 – 268 Define the following terms: solution, homogeneous mixtures, solute, solvent, alloy, and aqueous solutions How are solutions classified? Utilize p. 266 Table 1 for examples What are some properties of aqueous solutions? Provide key terms, definitions and examples of each. Assigned Questions: p. 269 Practice UC #1, 2, 3, 4, 5, 6, 7 2

Define a Solution Summary Activity Read pp. 266 – 268 Define the following terms: solution, homogeneous mixtures, solute, solvent, alloy, and aqueous solutions How are solutions classified? Utilize p. 266 Table 1 for examples What are some properties of aqueous solutions? Provide key terms, definitions and examples of each. Assigned Questions: p. 269 Practice UC #1, 2, 3, 4, 5, 6, 7 3

Define a Solution Summary Activity Read pp. 266 – 268 Define the following terms: solution, homogeneous mixtures, solute, solvent, alloy, and aqueous solutions How are solutions classified? Utilize p. 266 Table 1 for examples What are some properties of aqueous solutions? Provide key terms, definitions and examples of each. Assigned Questions: p. 269 Practice UC #1, 2, 3, 4, 5, 6, 7 4

Explaining Solutions

6 Bonding Forces Intramolecular Forces “intra” means within forces that bond atoms and ions within a compound Intermolecular Forces “inter” means between responsible for how molecules arrange themselves in an orderly fashion (i.e. lattice structure) relatively weak compared to intramolecular (e.g. covalent bonds)

Explaining Solutions7 Polar Covalent Bonds when atoms are identical (e.g. Cl 2 ) the electrons are share equally however, when two different elements form bond the electron sharing is unequal, bonding electrons spend more time near one atom than the other Ex. H-Cl (because Cl is more electronegative than H, it has a greater ability to attract electrons when bonded and as a result Cl is slightly negative and H is slightly positive)

Explaining Solutions8 “slightly” is represented by the Greek letter delta (  ) which represents small difference Example :  + H – Cl  - In general, if the absolute value of the difference in electronegativities is 1.7 or less the bond tends to be polar covalent (Review p. 83 Table 1 and p. 84 Figure 3)

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Explaining Solutions11 Polar Molecules if a molecule contains polar covalent bonds, the entire molecule may have a positive end and a negative end. Therefore, called a polar molecule however, not all molecules with polar covalent bonds are polar molecules (e.g. HCl and CCl 4 ) Review Guidelines for Predicting Polar and Nonpolar Molecules p. 85 Table 3

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Explaining Solutions14 Intermolecular Forces van der Waals forces (2 types) London dispersion forces –exist between ALL molecules, polar or nonpolar –result of temporary shift of electron “cloud” around atoms in molecule, they are short- lived dipoles (lasts tiny fractions of seconds)

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Explaining Solutions16 Dipole-dipole forces –forces of attraction between oppositely charged ends of polar molecules –positive end of each molecule attracts negative end of neighbouring molecules (kinda, like a weak version of ionic bond)

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Explaining Solutions18 Hydrogen Bonds occur among highly polar molecules containing F – H, O – H, and N –H bonds hydrogen bonds are much stronger than van der Waals water tends to “stick together” because of these bonds

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Intermolecular Forces Explaining Solutions21

SEATWORK Read and Summarize pp. 273 – 275 -Explaining molecular substances in water -The effects of polarity and hydrogen bonds Read Lab Exercise Predicting High and Low Solubilities (pp ) - Within a small group answer the Prediction (a) Explaining Solutions22

23 Predicting High and Low Solubilities (pp ) Highest Solubility - Acetic Acid and Methanol Molecules are polar Formation of hydrogen bonds with water molecules High Solubility - Dimethyl ether Molecule is polar Presence of oxygen atom means some hydrogen bonding with O-H ends of water molecules Slightly Soluble - Carbon dioxide and Oxygen Should be non-polar, but oxygen presence means that there is a possibility of some hydrogen bonding with water molecules. Insoluble - Propane and Tetrachloromethane Nonpolar molecules Little or no solubility in water, cannot participate in dipole- dipole forces and hydrogen bonding

Explaining Solutions24 SEATWORK Assigned Questions p. 277 # 3, 4, 5 Read and Summarize pp Ionic compounds in water -Explaining non-aqueous mixtures -Water – “The Universal Solvent”