Presentation on theme: "Acids and Bases. Acids: Compounds that dissociate (give off) one or more hydrogen ions (H+) when dissolved in water (proton donors) Bases: Compounds that."— Presentation transcript:
Acids: Compounds that dissociate (give off) one or more hydrogen ions (H+) when dissolved in water (proton donors) Bases: Compounds that dissociate (give off) one or more hydroxide ions (OH-) when dissolved in water (proton acceptors)
The pH Scale pH is a measure of H + ion concentration. The formula for calculating pH is: pH = -log[H + ]
The pH Scale The pH Scale pH = -log[H + ] I Do: A solution has a hydrogen ion concentration of 0.001 M. What is the pH of this solution?____ We Do: What is the pH of a solution with a hydrogen ion concentration of 0.0001 M?_______ You Do: What is the pH value of a solution that has a hydrogen ion concentration of 0.0000005 M?_______
The pH Scale Acids have a pH value less than 7. Bases have a pH value greater than 7. Neutral substances have a pH of exactly 7. (Alkaline is another way to say basic)
pH Indicators An indicator is a compound used to detect the presence of H + ions in solution. Indicators typically change color when exposed to acids and bases and can be used to determine whether a substance is acidic, basic, or neutral. Some common indicators are: Litmus paper (turns red when exposed to acid, blue when exposed to base) Phenolphthalein (clear = acid, pink = base) Universal indicator (red = acid, blue = base) Bromothymol blue (yellow = acid, blue = base) Cyanidin (red cabbage juice) (red = acid, yellow/green = base) Phenol red (yellow = acid, red = base)
Properties of Acids Acids taste sour Acids have a pH lower than 7 Acids effect indicators Blue litmus turns red Universal indicator turns red
Properties of Acids Acids are proton (hydrogen ion, H + ) donors Acids react with active metals, produce H 2 Acids react with carbonates Acids neutralize bases
Acids Effect Indicators Blue litmus paper turns red in contact with an acid.
Formation of Hydronium ion, H 3 O + H 2 O + HCl H 3 O + + Cl - Proton donor Proton acceptor Hydronium
Acids and Bases Can Be Strong or Weak Strong acids are assumed to be 100% ionized in solution (good proton donors). Weak acids are usually less than 5% ionized in solution (poor proton donors). HClH 2 SO 4 HNO 3 H 3 PO 4 HC 2 H 3 O 2 Organic acids
Acids Can Be Strong or Weak Which acid is a strong acid?____________ How do you know? Which acid is a weak acid? ___________ How do you know?
Acids and Bases Can Be Concentrated or Dilute A concentrated solution contains a high amount of solute per liter of solution. Example: 12M HCl A dilute solution contains a low amount of solute per liter of solution. Example: 0.01 M HCl
Acids and Bases Can Be Concentrated or Dilute Which solution is most concentrated? ___ How do you know? Which solution is lease concentrated?___ How do you know? A B
Neutralization Neutralization What happens when an acid is mixed with a base? Neutralization!
Products of Neutralization HCl + NaOH H 2 SO 4 + Ca(OH) 2 The products of neutralization are always a ______ and _______. NaCl + H 2 O CaSO 4 + 2 H 2 O salt water