1 Chapter 8 Solutions 8.1 Solutions The water lost from the body is replaced by the intake of fluids.

2 Solute and Solvent Solutions are homogeneous mixtures of two or more substances contain a solute, usually in smaller quantity contain a solvent, usually in greater quantity

3 Solutes spread evenly throughout the solution cannot be separated by filtration can be separated by evaporation are not visible but can give a color to the solution Nature of Solutes in Solutions

4 Examples of Solutions The solutes and solvents in solutions can be solids liquids gases

5 Identify the solute in each of the following solutions: A. 2 g of sugar (1) and 100 mL of water (2) B mL of of ethyl alcohol(1) and 30.0 mL of methyl alcohol (2) C mL of water (1) and 1.50 g of NaCl (2) D. Air: 200 mL of O 2 (1) and 800 mL of N 2 (2) Learning Check

6 Identify the solute in each of the following solutions: A. 2 g of sugar (1) B mL of methyl alcohol (2) C. 1.5 g of NaCl (2) D. 200 mL of O 2 (1) Solution

7 Water is the most common solvent Review electronegativity -

8 Water is the most common solvent Draw a water molecule Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons. The Pauling scale is the most commonly used. Fluorine (the most electronegative element) is assigned a value of 4.0, and values range down to caesium and francium which are the least electronegative at 0.7.

9 Water is the most common solvent is a polar molecule forms hydrogen bonds between the hydrogen atom in one molecule and the oxygen atom in a different water molecule

10 Formation of a Solution Na + and Cl  ions on the surface of a NaCl crystal are attracted to polar water molecules in solution are hydrated as several H 2 O molecules surround each

Attractions in Solutions Interactions between solutes and solvents that are similar in polarity will form a solution are not similar will not form a solution 11

12 When NaCl(s) dissolves in water, the reaction can be written as H 2 O NaCl(s) Na + (aq) + Cl  (aq) solid separation of ions Equations for Solution Formation

13 Solid LiCl is added to water. It dissolves because A. the Li + ions are attracted to the 1) oxygen atom (  - ) of water 2) hydrogen atom (  + ) of water B. the Cl  ions are attracted to the 1) oxygen atom (  - ) of water 2) hydrogen atom (  + ) of water Learning Check

14 Solid LiCl is added to water. It dissolves because A. the Li + ions are attracted to the 1) oxygen atom (  - ) of water. B. the Cl  ions are attracted to the 2) hydrogen atom (  + ) of water. Solution

15 Two substances form a solution when there is an attraction between the particles of the solute and solvent when a polar solvent such as water dissolves polar solutes such as sugar and ionic solutes such as NaCl when a nonpolar solvent such as hexane (C 6 H 14 ) dissolves nonpolar solutes such as oil or grease Like Dissolves Like

16 Water and a Polar Solute

17 Like Dissolves Like Solvents Solutes Water (polar) Ni(NO 3 ) 2 CH 2 Cl 2 (nonpolar) (polar) I 2 (nonpolar)

18 Will the following solutes dissolve in water? Why? 1) Na 2 SO 4 2) gasoline (nonpolar) 3) I 2 4) HCl Learning Check

19 Will the following solutes dissolve in water? Why? 1) Na 2 SO 4 Yes, the solute is ionic. 2) gasoline No, the solute is nonpolar. 3) I 2 No, the solute is nonpolar. 4) HClYes, the solute is polar. Most polar and ionic solutes dissolve in water because water is a polar solvent. Solution

20 Solutions Continued Properties of Solutions Ethylene glycol is added to a radiator to form a aqueous solution that has a lower freezing point than water.

21 Solutions contain small particles (ions or molecules) that are uniformly dispersed in the solvent are not separated by filters or a semipermeable membrane

22 Colloids contain large solute particles that are uniformly dispersed in the solvent cannot be separated by filtration can be separated by semipermeable membranes

23 Examples of Colloids

24 Suspensions have very large particles that settle out are separated by filters must be stirred to stay suspended Examples: blood platelets, muddy water, and calamine lotion

Properties of Different Types of Mixtures 25

Solutions Colloids, and Suspensions 26