Understanding Solutions Solution – A well mixed mixture – Ex Water(H2O) & Salt( NaCl)  The salt dissolves & the dissolved particles ( can’t see them) are much smaller than suspended particles. Suspension – A mixture in which particles can be seen & easily separated by settling or filtration. Ex. Pepper in water

Understanding Solutions 3. Solvent – The part of a solution that is present in the largest amount. It dissolves other substances. 4. Solute – A substance that is present in a solution in a smaller amount. It is dissolved by the solvent. 5. Water – “ Universal solvent” In many common solutions the solvent is water. Ex.’s: Blood, Saliva, Tears, & Sweat

Understanding Solutions 6. Solutions & Conductivity – Salt Solution vs. Sugar Solution Conducts Does Not Electricity Conduct Electricity 7. Particles in Solution – When a solution forms, particles of the solute leave each other & become surrounded by solvent (water). H2O H2O H2O Salt H2O H2O Sugar H2O H2O H2O

Understanding Solutions 8. Colloids – A mixture with small un-dissolved particles that do not settle out. Colloidal particles scatter light. Solutions and suspensions do not scatter light. Examples of colloids are gelatin, whipped cream & milk. 9. Lower Freezing Points – Solutes lower the freezing point of a solvent. Salt water freezes at -4 0 C. Fresh water freezes at 0 0 C.

Understanding Solutions 10. Higher Boiling Points – Solutes raise the boiling point of a solvent. Salt water boils at 104 o C. fresh water boils at 100 o C. 11. Dilute Solution – Only a little solute is dissolved in the solvent. 12. Concentrated Solution - A lot of solute dissolved in the solvent.

Understanding Solutions 13. Measuring Concentration – You compare the amount of solute to the amount of solvent or you compare the solute to the total amount of the solution. Ex.’s 10 g NaCl / 100mL H20 = 1g / 10mL or A 70% NaCl solution means 70% of the solution is NaCl

Understanding Solutions 14. Solubility – A measure of how well a solute can dissolve in a solvent at a given temp. 15. Saturated Solution – Contains as much dissolved solute as possible at a given temperature. 16. Unsaturated Solution – Does not contain as much of a solute as is possible at a given temperature. 17. Changing Solubility – By manipulating temperature, pressure & the type of solvent -

Understanding Solutions 18. Temperature – For most solids as the temperature increases their solubility increases. Ex. Sugar 19. Pressure – Changes the solubility of gases. The higher the pressure the more gas that can dissolve. 20. Solvents – Liquids -> Polar (Water) vs. Non polar (Oil) – Polar & Ionic compounds dissolve in water ( Vitamin C in water). Non Polar compounds dissolve in oil ( Vitamins A, D, E & K dissolve in oil (fat).

Understanding Solutions 21. Properties of Acids – a. Taste Sour – Lemon, Lime –citric acid b. React with Metals – Acids react with (corrode) metals to produce hydrogen gas. c. React with Carbonates – Acids react with carbonates (CO3-3) to produce CO2 gas. d. React with Indicators – Acids turn blue litmus paper red.

Understanding Solutions 22. Properties of Bases – a. Bitter Taste – Tonic Water, Soaps & Shampoos b. Slippery Feel – Bar of wet soap c. React with Indicators – Bases turn red litmus paper blue. d. Bases do not react with metals or carbonates.

Understanding Solutions 23. Acid – Any substance that produces hydrogen ions [H+] in water. HCL + water  H+ + Cl- 24. Hydrogen Ion [H+] – An atom of hydrogen that has lost its electron. 25. Base – Any substance that produces hydroxide ion [OH-] in water. NaOH + water  Na+ + OH- 26. Hydroxide Ion [OH-] – A polyatomic ion made of oxygen and hydrogen that has a negative charge.

Understanding Solutions 27. Strong Acid – Produces more [H+] in water than a weak acid. Ex. HCL 28. Strong Base – Produces more [OH-] in water than a weak base. 29. Measuring pH – Knowing the concentration of [H+] is the key to knowing how acidic or basic a solution is.

Understanding Solutions 30. pH Scale – A numeric scale with a range of values from 0 to 14. When the pH is low the concentration of [H+] is high. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Acidic Neutral Basic Stomach Acid Pure Drain Cleaner HCl Water NaOH

Understanding Solutions 31. Acid Rain – Sulfur oxides & nitrogen oxides, pollutants from industry and motor vehicles react with rain in the air to make sulfuric acid & nitric acid. 32. Neutralization Reaction – a reaction between an acid and a base. The acid- base mixture is not as acidic or basic as the individual starting solutions. This type of reaction always produces water and a salt.

Understanding Solutions 33. Digestion – Food must be broken down into simpler substances that your body can use for raw materials & energy. Decomposition Rx.’s -> Complex to Simple 34. Mechanical Digestion – A physical process in which large pieces of food are torn & ground into smaller pieces. 35. Chemical Reaction – A set of reactions that turn large molecules into smaller molecules. Enzymes are used. Some require a high pH. Some require a low pH.

Understanding Solutions 36. Mouth – Food is chewed & mashed by teeth (physical). Saliva (chemical) is mixed with food. The pH of saliva is about 7. Amylase, an enzyme in saliva breaks carbohydrates down into smaller sugar molecules. 37. Stomach – Cells in the lining of the stomach release enzymes & HCl with a pH of 2. Pepsin, an enzyme in gastric juice breaks down proteins into smaller amino acids.

Understanding Solutions 38. Small Intestine – Produces bicarbonate ion [HCO3-1] with a pH of 8. All enzymes in the sm. Intestine work better at a basic ph.