Acids Acids and and

BasesBases

Acids:Acids: Compounds that Compounds that dissociate (give off) one or dissociate (give off) one or more more hydrogen ionshydrogen ions (H+) (H+) when dissolved in water when dissolved in water (proton donors)(proton donors)

Bases:Bases: Compounds that Compounds that dissociate (give off) one or dissociate (give off) one or more more hydroxide ionshydroxide ions (OH-) (OH-) when dissolved in water when dissolved in water (proton acceptors)(proton acceptors)

The pH ScaleThe pH Scale

pH is a measure of H+ ion concentration.

The formula for calculating pH is:

pH = -log[H+]

The pH ScaleThe 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 ScaleThe 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 IndicatorspH Indicators

An An indicator indicator is a compound used to detect the presence of His a compound used to detect the presence of H++ ions in solution. Indicators typically change color when ions in solution. Indicators typically change color when exposed to acids and bases and can be used to determine exposed to acids and bases and can be used to determine whether a substance is acidic, basic, or neutral. Some whether a substance is acidic, basic, or neutral. Some common indicators are:common indicators are:

  

Litmus paper (turns red when exposed to acid, blue when Litmus paper (turns red when exposed to acid, blue when exposed to base) exposed to base)

Phenolphthalein (clear = acid, pink = base)Phenolphthalein (clear = acid, pink = base)

Universal indicator (red = acid, blue = base) Universal indicator (red = acid, blue = base) Bromothymol blue (yellow = acid, blue = base) Bromothymol blue (yellow = acid, blue = base)

Cyanidin (red cabbage juice) (red = acid, yellow/green = Cyanidin (red cabbage juice) (red = acid, yellow/green = base) Phenol red (yellow = acid, red = base) Phenol red (yellow = acid, red = base) base)

Properties of AcidsProperties of Acids

Acids taste sourAcids have a pH lower than 7Acids effect indicators

Blue litmus turns redUniversal indicator turns red

Properties of AcidsProperties of Acids

Acids are proton (hydrogen ion, H+) donors Acids react with active metals, produce H2

Acids react with carbonates Acids neutralize bases

Acids Effect IndicatorsAcids Effect Indicators

Blue litmus paper turns red in contact with an acid.

Acids Acids Have a pH Have a pH less than less than

77

Properties of BasesProperties of Bases Bases taste bitterBases have a pH greater than 7 Bases effect indicators

Red litmus turns blueUniversal indicator turns bluePhenolphthalein turns purple

Properties of BasesProperties of Bases

Bases are proton (H+) acceptors and usually have hydroxide ions- OH- Solutions of bases feel slippery Bases neutralize acids

Bases Effect Bases Effect IndicatorsIndicators

Red litmus paper turns blue in contact with a base. Phenolphthale

in turns purple in a base.

Bases Bases have a pH have a pH

greater greater than 7than 7

Common Strong AcidsCommon Strong Acids

Sulfuric Acid, H2SO4

Perchloric acid, HClO4

Hydrochloric Acid, HCl

Hydrobromic Acid, HBr

Nitric Acid, HNO3

Hydroiodic Acid, HI

Common Strong BasesCommon Strong Bases

Lithium Hydroxide, LiOH Sodium Hydroxide, NaOH

Potassium Hydroxide, KOH Calcium Hydroxide Ca(OH)2

Strontium Hydroxide, Sr(OH)2 Barium Hydroxide, Ba(OH)2

Common Weak AcidsCommon Weak Acids

Formic Acid, HCOOH

Acetic Acid, CH3COOH

Hydrofluoric, Acid HF

Hydrocyanic acid, HCN

Common Weak BasesCommon Weak Bases

Sodium hydroxide, NaOH Ammonia, NH3

Potassium hydroxide, KOH Calcium hydroxide, Ca(OH)2

Formation of Formation of HydroniumHydronium ion, ion, HH33OO++

H2O + HCl H3O+ + Cl-

Protondonor

Protonacceptor

Hydronium

Acids and Bases Can Be Acids and Bases Can Be Strong or WeakStrong 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).

HCl

H2SO4 HNO3

H3PO4 HC2H3O2 Organic acids

Strong Acid DissociationStrong Acid Dissociation

Weak Acid DissociationWeak Acid Dissociation

Acids Can Be Strong or WeakAcids Can Be Strong or Weak

Which acid is a Which acid is a strong acid?____________ strong acid?____________

How do you know?How do you know?

Which acid is a weak Which acid is a weak

acid? ___________acid? ___________

How do you know?How do you know?

Acids and Bases Can Be Acids and Bases Can Be Concentrated or DiluteConcentrated 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 Acids and Bases Can Be Concentrated or DiluteConcentrated or Dilute

Which solution is most concentrated? ___ How do you know?Which solution is lease concentrated?___How do you know?

A B

NeutralizationNeutralization

What happens when an acid is mixed with a base?

Neutralization!

Products of NeutralizationProducts of Neutralization

HCl + NaOH H2SO4 + Ca(OH)2

The products of neutralization are always a ______ and _______.

NaCl + H2O

CaSO4 + 2 H2O

salt water