1. Solutes, Solutions and Solvents Unique properties of water Chapter 2.2

2. KEY CONCEPT Water’s unique properties allow life to exist on Earth.

3. O HH _ ++ Life depends on hydrogen bonds in water. Water is a polar molecule. – Polar molecules have slightly charged regions. – Nonpolar molecules do not have charged regions. – Hydrogen bonds form between slightly positive hydrogen atoms and slightly negative atoms.

4. Hydrogen bonds are responsible for three important properties of water. –high specific heat –cohesion –adhesion

5. Many compounds dissolve in water. A solution is formed when one substance dissolves in another. – A solution is a homogeneous mixture. – Solvents dissolve other substances. – Solutes dissolve in a solvent. solution

6. Solvent, Solute, Solution

7. Give an Example… solution - salt water solvent - water solute - salt solution - lemonade solvent - water solute - lemonade mix solution - hot chocolate solvent - water solute - hot chocolate mix Chocolate square -- solute Saliva—solvent Liquid chocolate in mouth mixed in saliva-solution

8. Water is called the universal solvent …. because, given enough time, it will dissolve just about anything. There are two main factors that increase how fast something will dissolve: agitation and temperature.

9. “Like dissolves like.” –Polar solvents dissolve polar solutes. –Nonpolar solvents dissolve nonpolar solutes. –Polar substances and nonpolar substances generally remain separate. solution - salt water solvent - water solute - salt solution - lemonade solvent - water solute - lemonade mix solution - hot chocolate solvent - water solute - hot chocolate mix Chocolate square -- solute Saliva—solvent Liquid chocolate in mouth mixed in saliva- solution

10. One more thing… For a solvent to break down a solute, it must be in contact with the surface area of the solute. The more surface area the solvent is exposed to, the quicker it can break down the solute. So cocoa mix breaks down faster than a solid piece of chocolate melting in hot milk.

11. Some compounds form acids or bases. An acid releases a hydrogen ion when it dissolves in water. – high H + concentration – pH less than 7 more acidic stomach acid pH between 1 and 3

12. A base removes hydrogen ions from a solution. –low H + concentration –pH greater than 7 bile pH between 8 and 9 more basic

13. A neutral solution has a pH of 7. pure water pH 7