Objectives Learn the properties and definitions of acids / bases

Properties of Acids 1. sour to taste 2. have hydrogen in front of formula: HCl, H 2 SO 4 3. pH range is from dissolved in water (aqueous) –contains more hydronium(H 3 O + ) ions than hydroxide(OH - ) ions 5. turns litmus paper red 6. feel “rough” 7. conduct electricity in solution 8. react with metals to produce hydrogen gas 9. corrosive 10. proton donors (H+) 11. neutralize bases

Properties of Bases 1.bitter to taste 2.the formula usually ends in OH (hydroxide): NaOH – an exception is NH 3 (ammonia) 3.pH range is from dissolved in water (aqueous) –contains more hydroxide ions than hydronium ions 5.turns litmus paper blue 6.feel “slippery” 7.conduct electricity in solution 8.a strong base can be just as harmful as a strong acid 9.neutralize acids 10.proton acceptors (H+) 11.react with oils and greases (used as cleaners)

Acids reaction with Metal Acids can be identified by their reaction with some metals to produce hydrogen gas For example: Aluminum reacts with aqueous solutions of hydrochloric acid to produce hydrogen gas and aluminum chloride.

Ion Concentration is used to identify solutions of acids and bases. Aqueous solutions of acids cause blue litmus paper to turn Red and aqueous solutions of bases cause red litmus paper to turn BLUE. Solutions are ACIDIC, BASIC, or NEUTRAL due to the relative amount of Hydrogen (H+) ions and Hydroxide (OH-) ions in solution.

If Hydrogen ions are greater than Hydroxide ions, the solution is Acidic In acidic solutions, [H+] >[OH–] If Hydroxide ions are greater than Hydrogen ions, the solution is basic. In basic solutions, [OH–] > [H+] If Both ions are equal then the solution is neutral. [H+] and [OH–] are both 1.0 X or pH = 7 and pOH = 7

Arrhenius Theory (H or OH will appear in the formula) -Acids produce ____H+ Ions________ in aqueous solution. EX: -Bases produce _____OH- Ions________ in aqueous solution. EX:

Bronsted-Lowry Theory -Acids are __________Proton Donors_____________________. -Bases are _____________Proton Acceptors____________. An H + ion is transferred from an acid to a water molecule to produce the __Hydronium Ion ____. HX + H 2 O → H X - When an acid donates a proton, what remains is called the Conjugate Base. When a base receives a proton, the species that forms is called the Conjugate Acid.

Conjugate Acid-Base Pairs A conjugate acid is the species produced when a base accepts a hydrogen ion from an acid. The conjugate base is the species that results when an acid donates a hydrogen ion to a base. Example: HC 2 H 3 O 2 + H 2 O ↔ H 3 O+ + C 2 H 3 O 2− acid base conjugate conjugate acidbase

Identify the conjugate acid-base pairs in the following reactions. NH 4 + (aq) + OH - (aq) ↔ NH 3 (aq) + H 2 O HBr(aq) + H 2 O(l) ↔ H 3 O + (aq) + Br - (aq) CO 3 2- (aq) + H 2 O(l) ↔ HCO 3- (aq) + OH - (aq) HSO 4 - (aq) + H 2 O(l) ↔ H 3 O + (aq) + SO 4 2- (aq)

Strength of Acids Strong acids are acids that ionize completely Because they ionize completely they are good conductors of electricity Rules to determine strong acids: 1)Binary acids: HCl, HBr, HI are strong 2)Ternary acids: General rule: if the # of oxygen atoms exceeds the number of hydrogen atoms by two or more, the acid is strong: HClO 4, H 2 SO 4, HNO 3 HCl --> H+ + Cl- This is a strong acid and the reaction goes to completion and is shown with only one arrow. That means that if you have 1M HCl you yield 1M H+ and 1M Cl-. Weak acids partially ionize/dissociate in water HF H+ + F- This is a weak acid and the reaction does not go to completion and is shown with a double arrow.

Strengths of Bases Strong bases dissociate entirely into metal ions and hydroxide ions Rules to determine strong bases: In general, Groups I and II metallic hydroxides are considered strong. All others are weak. NaOH  Na+ + OH- This is a strong base and the reaction goes to completion and is shown with only one arrow. That means that if you have 1M NaOH you yield 1M Na+ and 1 M OH-. Weak bases partially ionize/dissociate in water NH 3 + H2O  NH OH- This is a weak base and the reaction does not go to completion and is shown with a double arrow.

What is pH? A.Water self-ionizes by the following rxn: 2 H 2 O H 3 O+ + OH- B.Kw=[H 3 O+][OH-] where Kw=ion product constant for water Kw=1.008x10 25°C

Example Problem: At 298 K, the H+ ion concentration of an aqueous solution is 1.0 x M. What is the OH- ion concentration in the solution? Is the solution acidic, basic or neutral?

A. pH= negative logarithm of the hydronium ion (hydrogen ion) concentration in solution B. pH is a logarithmic scale (based on powers of ten) 1.numbers are more manageable 2.scale from 0 to 14 C. pH = - log [H+] or pH = -log[H 3 O+] (same thing) D. Practice finding the pH of solutions with the following [H+]: [H+] = 1 x M pH = [H+] = 3.5 x M pH= [H+] = 5.5 x M pH =

A.Pure Water Equilibrium H 2 O H + + OH - 1. Remember, for pure water: if: pH = 7, [H+] = 1 x M and: [H+] = [OH-] then:[OH-] = 1 x M 2. pOH scale used to express [OH-] (molar concentration of OH- ions) in solution pOH = -log[OH-] 3. pOH and pH are related by the statement: pH + pOH = 14

4. Practice finding the pOH and pH for the following [OH-] [OH-] = 3.4 x M pOH = pH = [OH-] = 6.7 x M pOH = pH = [OH-] = 5.5 x M pOH = pH =

A. To find the [H+] you will need to use the anti-log function or the 10x button on your calculator. B. Formula will be: [H+] = 10 -pH or [OH-] = 10 -pOH C. STEPS 1. enter the -pH value (change the sign of the pH) 2. Push the second log (antilog key 10x) 3. Change calculator to SCI Mode for best answer D. Practice with these pH and pOH values. pH = 6.7pOH = 2.5pH = 9.9 [H+] =[OH-] =[H+] =

Putting it all together A. By knowing any of the [H+], pH, or pOH values all other values can be calculated. B. Calculate the unknown values. C. Determine whether the substance is acidic or basic.

Practice [H+] = 3.46 x MpH = 8.90 pH =pOH = pOH =[H+] =[OH-] = [OH-] = 8.32 x MpOH = 3.71 pOH =[OH-]pH= [H+]= [H+] =

Naming Acids 1. Name these compounds as acids. a. HF b. HC2H3O2 c. H2SO4 d. HNO2 2. Write formulas for the following acids. a. chromic acid b. hydroiodic acid c. chlorous acid d. perchloric acid

Neutralization Reactions (acid-base reactions) A. General Rxn. : acid + base → salt + water Example: HCl + KOH → KCl + H2O B. water produced from the union of a H+ from acid and OH- from base C. Salt: compound formed from the positive ion of an aqueous base (other than hydrogen) and the negative ion of an aqueous acid (other than hydroxide) {NOT ALWAYS NaCl} D. Equal amounts of H+ and OH- will neutralize completely

Volumetric Calculations M 1 V 1 = M 2 V 2