Acids and Bases

Acids Sour tastes pH: 0 – 6.9 Reacts with carbonate to produce CO2 gas. Turns Litmus from Blue to Red. Reacts with metals to produce hydrogen gas.

Acids Acids Solutions conduct electricity (In ion form) Strong (99%) HCl (aq) + H2O (l) H+ (aq) + Cl- (aq) or H2SO4 (aq) + H2O (l) H+ (aq) + HSO4- (aq) Weak or strong acids depends on how much the acid dissociates.

Bases Bitter Taste pH: 7.1 – 14 Turns Litmus from Red to Blue Reacts with acids to form salts. Slippery feel

Bases Weak or Strong depends on how much it dissociates. Weak (4%) Na2CO3 (aq) + H2O (l) Na+ (aq) + CO3- (aq) Strong (99%) NaOH (aq) + H20 (l) Na+ (aq) + OH- (aq)

What is an Acid and What is a Base? Define acid and base in terms of water. H2O or HOH H-OH <Molecular Structure H+ = Hydrogen (Acid) OH- = Hydroxide (Base) If you have more hydrogen then hydroxide, you have an acid

What is an Acid and What is a Base? If you have more hydroxide then hydrogen you have a base. H+ = Acid OH- = Base HOH (H2O) = Neutral We measure acid and Base on the “pH” scale.

What is an Acid and What is a Base?

pH Scale The pH scale goes from 0 14

pH Scale Acid: pH 0 – 6.9 Base: pH 7.1 – 14 pH of 7 = Neutral pH

Common Acids Hydrochloric Acid = HCl Sulfuric Acid = H2SO4 Nitric Acid = HNO3

Common Bases Sodium Hydroxide = NaOH Ammonium Hydroxide = NH4OH Potassium Hydroxide = KOH

Types of Acids Monoprotic acids contain only one acidic hydrogen.

Types of Acids Diprotic contains 2 acidic hydrogens Triprotic contains 3 acidic hydrogens Polyprotic- more than 1 acidic hydrogen

Types of Acid Most acids are oxyacids, where the acidic proton is attached to an oxygen atom. HNO3 Nitric Acid H2SO4 Sulfuric Acid H3PO4 Phosphoric Acid

Types of Acids Amphoteric- can act as an acid or a base. H2O + H2O H3O+ + OH- Acid (1) Base (1) Acid (2) Base (2) The above is an autoionization of H2O, and involves the transfer of a proton from one water molecule to another to produce a OH- and H3O+.

Buffers and Buffer Solutions A buffered solution is one that “resists a change is its pH”, when either a hydroxide, OH- or hydrogen, H+, are added. Blood is a good example of a buffer. A buffer contains 2-components: an acid to neutralize the addition of OH-, and a base to neutralize the H+ from the addition of an acid.

Buffers and Buffer Solutions When base (OH-) is added to a buffer solution, the acid in the buffer provides H+ ions, which neutralizes the base, thus, preventing a large change in pH.

Buffers and Buffer Solutions The blood’s primary buffer system is made up of carbonic acid (H2CO3) and sodium bicarbonate(NaHCO3). H+ + HCO3- H2CO3 From Acid In Buffer Carbonic Acid OH- + H2CO3 HCO3- + H2O From Base In Buffer Bicarbonate Ion Buffer is weak base ammonia and its salt, used equation on page 531 to explain the buffer system.

Buffers and Buffer Solutions Original Buffer pH Added OH- ion replaced by acid ion or Added H+ ion replaced by base ion Final pH of Buffer Close to original

Acids and Bases Bases are ionic compounds containing metal cations and the hydroxide ion, OH-. When a “Base” completely dissociates in water to produce OH-, it is referred to as Alkaline.

Bronsted-Lowery Acids and Bases Bronsted–Lowery Acid is a molecule or ion that is a proton (H+) donor. Bronsted-Lowery Base is a molecule or ion that is a proton (H+) acceptor.

Bronsted-Lowery Bronsted-Lowery Acid is a molecule that is a Proton Donor. Example HCl + NH3 NH4+ + Cl- The proton is transferred from the hydrogen chloride to ammonia.

Bronsted-Lowery Bronsted-Lowery Base is a molecule that is a proton acceptor. Example HCl + NH3 NH4+ + Cl- Proton Proton Donor Acceptor Acid Base

Dissociates / Ionizes A strong acid is one that ionizes completely in an aqueous solution. A strong acid is a strong electrolyte. Electrolyte – Any compound that conducts electricity when melted or dissolved in water.

Dissociates / Ionizes Acids that are weak electrolytes are known as weak acids. They do not dissociate or ionize very much. Dissociation- The separation of ions that occurs when an ionic compound dissolves. Ionization-The process where ions form from a covalent compound.

Dissociates / Ionizes

Arrhenius Acids and Bases An Arrhenius Acid is a chemical compound that increases the concentration of hydrogen ions, H+, in an aqueous solution. Arrhenius Base is a substance that increases the concentration of hydroxide ions, OH-, in an aqueous solution.

Conjugated Acid and Bases When an acid gives up a proton, it can re-accept the proton and acts as a base. HF + H2O F- + H3O+ Acid Base Conjugated Conjugated Base Acid In the above reaction the water molecule is a Bronsted-Lowery Base. The hydronium ion is now able to donate a hydrogen proton, so it is called a conjugated acid.

Lewis Acids and Bases A Lewis acid is an electron-pair acceptor. A Lewis base is an electron-pair donor. H+ + [ O – H ]- H O H Lewis Acid Lewis Base

Graphic organizer time!

Neutralization Reaction The reaction of an acid and base is called a neutralization reaction because the properties of both the acid and base are diminished of neutralized when they react.

Concentration of Solution The concentration of a solution is a measure of the amount of the solute (solid) in a given amount of solvent (Liquid). Molarity- The number of moles of a solute in one liter of solution. Molarity, M= Moles/Liter

Concentration of Solution If 3 moles of LiCl are added to 100 L of water, what is the molarity of the solution? 3 mol/100 L = 0.03 M of LiCl

Concentration of Solution If you put 20.0 g of NaOH in 1-liter of water, what is the molarity (M). 20.0g NaOH 1 mole = 0.5 mole 40.0 g NaOH 0.5 mol/1.0 L = 0.5 M of NaOH

Concentration of Solution If you put 50.0 g of HCl in 2.0 liters of water, what is the molarity (M)? 50.0g HCl 1 mole = 1.37 mole 36.46 g HCl 1.37 mol/2.0 L = 0.69 M of HCl

Concentration of Solution When making-up a solution: M1V1=M2V2 M1 = Initial or Beginning Molarity V1 = Initial or Beginning Volume M2 = Final or Ending Molarity V2 = Final or Ending Volume

Concentration of Solution If you have 300mL of a 0.5 M solution of HNO3. What volume of water needs to be added to get 0.8 M solution of HNO3? M1 = 0.5 M V1 = 300 mL M2 = 0.8 M V2 = ? M1V1=M2V2

If you have 56 mL of a 3 M solution of H2SO4 If you have 56 mL of a 3 M solution of H2SO4. What volume of water needs to be added to get 0.1 M solution of H2SO4? M1 = 3 M V1 = 56 mL M2 = 0.1 M V2 = ?

If you have 56 mL of a 3 M solution of H2SO4 If you have 56 mL of a 3 M solution of H2SO4. What will the concentration of H2SO4 be if we add 1000mL (1L) of water? M1 = 3 M V1 = 56 mL M2 = ? M V2 = 1000 mL

If you have 5 mL of a 12 M solution of HCl If you have 5 mL of a 12 M solution of HCl. What will the concentration of HCl be if we add 500mL (1L) of water? M1 = 12 M V1 = 5 mL M2 = ? M V2 = 500 mL

Acid-Base Titration The general process of determining the molarity of an acid or a base through the use of an acid-base reaction is called an acid-base titration.

Acid-Base Titration The known reactant molarity is used to find the unknown molarity of the other solution. Solutions of known molarity that are used in this fashion are called standard solutions. In a titration, the molarity of one of the reactants, acid or base, is known, but the other is unknown.