Acids

1. Acids and Salts Bases

2. What Is a Solution? • Solutions can be made from any combinations of solids, liquids, and gases.

4. Particles in a Solution • When a solution forms, particles of the solute leave each other and become surrounded by particles of the solvent.

6. Colloids and Suspensions • Colloids and suspensions are mixtures that have properties different from those of solutions.

8. Liquid water solution Effects of Solutes on Solvents • At 0ºC, pure water freezes, but water mixed with a solute does not. Solutes lower the freezing point of a solvent. Solid (frozen) water

9. Assessment • What is a solution? • Suppose you mix food coloring in water to make it blue. Have you made a solution or a suspension? Explain. • How are solutions different from colloids and suspensions?

10. Assessment • What happens to the solute particles when a solution forms? • What affects do solutes have on a solvent’s freezing and boiling points? • Why is the temperature needed to freeze ocean water lower than the temperature needed to freeze the surface of a freshwater lake? • Why does salt sprinkled on icy roads cause the ice to melt?

12. CONCENTRATION Definition: The amount of a substance per defined space. Concentration usually is expressed in terms of mass per unit volume.

13. To calculate the concentration of a solution, compare the amount of solute to the amount of solution and multiply by 100 percent. For example, if a solution contains 10 grams of solute dissolved in 100 grams of solution, then its concentration can be reported as 10 percent. Calculating a Concentration

14. A solution contains 12 grams of solute dissolved in 36 grams of solution. What is the concentration of the solution? Try This

15. Solubility • Solubility is a measure of how much solute can dissolve in a solvent at a given temperature.

16. Examples: Key Terms: unsaturated solution supersaturated solution An unsaturatedsolution can continue to dissolve more solute. A supersaturatedsolution has more dissolved solute than is predicted by its solubility at the given temperature. dilute solution A dilute solution is a mixture that has only a little solute dissolved in a certain amount of solvent. concentrated solution A concentrated solution is one that has a lot of solute dissolved in the same amount of solvent. solubility Solubility is a measure of how much solute can dissolve in a solvent at a given temperature. saturated solution A saturated solution contains so much solute that no more dissolves.

18. Assessment • What is concentration? • What quantities are compared when the concentration of a solution is measured? • Solution A contains 50 g of sugar. Solution B contains 100g of sugar. Can you tell which solution has a higher sugar concentration? Explain.

19. Assessment • What is solubility? • How can solubility help identify a substance? • What are the three factors that affect solubility?

20. Acid: A substance that releases H+ ions in an aqueous solution “aqueous” means: water

21. Characteristics of Acids: • Acids have a sour taste • Acids react with metals • Acids contain Hydrogen • Many are poisonous and corrosive to skin H

22. Strong Acids (break down completely to give off many H+ ions)

23. Weak Acids (only partially breaks down, gives less H+)

24. Common Acids: All others considered Weak (examples) Weak AcidThe Formula Acetic acid (vinegar) HC2H3O2 Carbonic acid HCO3

25. Base: A substance that releases OH- ions in an aqueous solution

26. Characteristics of Bases: • Bases usually taste bitter • Bases feel slippery • Bases contain hydroxide ions • STRONG bases are also poisonous and corrosive to skin OH-

27. Common Bases: (Hydroxides of Group 1 and Group 2 Metals are STRONG) All others are WEAK

28. Some bases (VERY FEW) don’t have OH- Most commonly: ammonia NH3

29. Section 3 Assessment • What are four properties of acids? Of bases? • How can you use litmus paper to distinguish and acid from a base? • How might you tell if a food contains an acid as one of its ingredients?

30. Section 3 Assessment • What are three practical uses of an acid? Of a base? • Where are you most likely to find acids and bases in your own home? Explain. • Why is it wise to wear gloves when spreading fertilizer in a garden?

31. Salts

32. Reactionsbetween acids and bases When and acid and a base react with each other, the characteristic properties of both are destroyed. This is called neutralization.

33. Reactions between acids and bases General formula for acid base reaction: Acid + Base → H2O + Salt “Salt” means any ionic compound formed from an acid/base reaction NOT JUST NaCl !!

34. Neutralization HCl + NaOH → H2O + NaCl acid base water salt

35. Neutralization Another Example HNO3 + KOH → H2O + KNO3 K OH H NO3 acid base water salt

36. pH pH stands for “potential hydrogen” and is a measure of how many H+ ions there are in solution. The MORE H+ there are, the LOWER the pH will be.

37. Indicators An indicator is a compound that will change color in the presence of an acid or base • Red Litmus-Turns blue in base • Blue Litmus-Turns red in acid • Universal indicator (pH paper) Used for the full pH range • Phenolphthalein-Turns pink in base

38. pH Scale Shows the range of H+ concentrations High H+ concentration Low H+ concentration

39. Section 4 Assessment • What does a substance’s pH tell you? • If a solution has a pH of 6, would the solution contain more or fewer hydrogen ions (H+) than an equal volume of solution with a pH of 3?

40. Digestion and pH