Magic Pitcher What is phenolphthalein? Examine table M. What do you think was in each of the following? Pitcher- Beaker 1 – Beaker 2 – Beaker 3 – Beaker 4 -

Electrolyte-Conducts electricity - ions into solution Nonelectrolyte - Does not put ions into solution -Will not conducts electricity All ionic substances can be electrolytes NaCl DissociationWhen IONIC compounds break apart in a liquid to form ions Na + Cl - CaCl 2 (s)  Ca 2+ (aq) + 2 Cl - (aq)

Example- Write out the dissociations for the following ionic compounds. a.KBr  b.MgCl 2  c.LiNO 3  d.Na 3 PO 4  K + (aq) + Cl - (aq) Mg +2 (aq) + 2 Cl - (aq) Li + (aq) + NO 3 - (aq) 3 Na + (aq) + PO 4 -3 (aq) Ionization- Process by which some polar molecules can be broken into “ions” H2SH2S H2SH2S H2SH2S H2SH2S H2SH2S H2SH2S H2SH2S H2SH2S 2 H + (aq) + S -2 (aq) Most is H 2 S, but a small portion is broken into ions H + H + S -2

Acids and bases are important to many parts of our life Acids Bases Vitamin C =Ascorbic acid Vinegar =Acetic Acid HCl is used for digestion Lye -Cleaning agent Used to refine soap, paper, rayon Milk of magnesiaMg(OH) 2 Table K – Names of common acids Table L – Names of common bases

Acids and bases are active only in solution Solid NaOH has no effect. In solution, it can dissolve clothing, skin, etc.

Cl Table J Any metal listed above H 2 will do this 2 HCl + Zn  ZnCl 2 + H 2(g) Properties of Acids Table K = names of common acids 1. Aqueous solutions of acids are electrolytes - Ions conduct electricity 2. Acids react with some metals to produce H 2(g) PbMgZn Cl Cl 2 ZnH

Water to grape to juice The first beaker contains water and phenolpthalein. What is in the second beaker? What is in the third beaker that returns the solution to colorless? Sodium bicarbonate is added to beaker 4 causing the release of carbon dioxide. Draw the electron dot structure for carbon dioxide. In beaker five the following reaction takes place H 2 SO 4 + Ba(NO 3 ) 2  HNO 3 + BaSO 4 What type of reaction is the one shown? Which of the products is the precipitate? Why did the beaker return to the pink color?

3. Acids affect the color of some indicators IndicatorChemical which changes its appearance in the presence of an acid or base Litmus paperBlue paper turns red Phenolphthalein pinkcolorless Turns from pink to colorless 4 Acids will react with bases (hydroxides) to form water and salt 5. Dilute acids have a sour taste Citric acid Lemon juice Acetic acidVinegar Bromthymol blue blue yellow Turns from blue to yellow Table M Neutralization Ex. NaOH + HCl  H 2 O + NaCl When diluting acids remember “ Do as you otter, add acid to water”

Arrhenius Theory – acids release H + (H 3 O + ) in solution Hydronium ion Properties of Bases 1. Aqueous solutions of bases are electrolytes 2. Bases cause indicators to change colors Litmus- Red litmus paper turns blue Phenolphthalein - clearpink Changes from clear to pink 4. Bases neutralize acids Most are poisonous and corrosive to the skin Bromthymol blue yellow to blue - Turns from yellow to blue - Conduct electricity when in solution 3. Bases taste bitter and are slippery Base + Acid  Water + Salt

Arrhenius Theory of Bases Base- Any substance that yields (OH - ) as the only negative ions in solution NaOH  Na + (aq) + OH - (aq) *** Just because it has OH does not mean that it is a base Ex. CH 3 OH – is methyl alcohol and is NOT a base

Neutralization Reaction -Occurs when an acid and base are mixed together - The H+ H+ from the acid and the OH - from the base combine to form water NaOH HCl H 2 O + NaCl NaOH + HCl --> The important part of the reaction is: H + + OH - --> H 2 O The overall reaction is:Acid + Base --> Salt + Water The Na+ and Cl- are not involved in the neutralization. These are referred to as SPECTATOR IONS H + Cl - Na + OH - H+H+ OH - H 2 O Notice how we need one H + for every OH - ? This will be important for our next section on Titrations

All properties of acids are due toH+H+ All properties of bases are due to OH- When H + meet OH-, water is created. H+H+ OH- H 2 O Since there are no more H + or OH-, the solution is neither acidic nor basic In order to completely neutralize a solution, we need the exact same number of H + from acids and OH- from bases Too many H +, still acidic. Too many OH-, still basic H+H+ H+H+ H+H+ H+H+ OH- H2OH2O H2OH2O H2OH2O H2OH2O AcidicNeutralBasic

Rainbow in a Cylinder Demo What is meant by universal indicator? Could the solution be reused?

Titration of Acids and Bases Titration- Procedure used to calculate the molarity of an unknown acid or base -Based on the fact that for every H +, we need one OH- in order to cancel it out - react unknown with a known molarity and volume M a V a = M b V b Ex. If 5.0 ml of 0.2 M solution is required to neutralize exactly 10.0 ml of NaOH, what is the concentration (molarity) of the base? M a = M b = V a = Vb =

Example -1. How many milliliters of 1.0 M HCl are needed to neutralize ml of a 2.0 M NaOH solution? M a x V a = M b x V b 1.0 xx =2.0 x200.0 ml x= ml = V a 2. How much 0.10 M HCl is needed to neutralize ml of a 0.30 M NaOH solution? M a x V a = M b x V b 0.10 M x V a = 0.30 M x ml V a = 600 ml M a = M b = V a = Vb = M a = M b = V a = Vb =

HCl creates only one H + NaOH creates only one OH- Since these two match up, we can use the simple formula. Sometimes the H + in the acid will not equal the OH- of the base. H 2 SO 4 Creates 2 H + LiOHCreates only 1 OH- In this case, we need to use a special formula n a xM a x V a = n b x M b x V b n a = number of H + in the acid n b = number of OH- in the base We would need 2 LiOH to neutralize one H 2 SO 4

Examples 1. What is the concentration of HCl if 30.0 ml of the acid are neutralized by 50.0 ml of a 3.0 M Ca(OH) 2 solution? n a xM a x V a = n b x M b x V b 1 x M a x 30.0= 2 x 3.0 x 50.0 M a = 10. M 2. How many ml of 0.50 M H 2 SO 4 is needed to neutralize ml of a 2.5 M KOH solution? n a xM a x V a = n b x M b x V b 2 x 0.50 x V a = 1 x 2.5 x V a = 250 ml n a = M a = M b = n b = V a = V b = n a = M a = M b = n b = V a = V b =

Changes in H + concentration Adding an acid or a base to water will alter the H + and the OH- concentration AcidIncreases [H + ] and decreases [OH-] Base Decreases [H + ] and increases [OH-] [H+][OH-][H]x [OH-] [H+][OH-][H]x [OH-] [H+][OH-][H]x [OH-] DON’T WRITE

pH scale - pH is defined as the -logarithum of the H + in solution pH = -log [H + ] This means that if the solution has 1 x M H +, the pH is Determine the pH of the following solutions [H + ] = 1 x M [H + ] = 1 x M [H + ] = 1 x M pH = Used to express the [H + ] in a solution - Is a number between 0 and 14 - Is a logarithmic scale DO NOT WRITE - Each pH number represents a 10x increase or decrease - As [H + ] increases the [OH - ] decreases

Questions 1. If the pH changes from 2 to 4, how much does the [H + ] change, and is it higher or lower? pH change of 2 changes [H+] by 10 x 10 or100x Since the pH goes up, the [H+] goes down pH scale is based on a 1-14 scale with 7 being neutral

If the [H + ] is high (1 x M), the pH is lower Low pH = High pH = Acidic Basic Acidic Basic pH = 3 If the [OH + ] is high (1 x M), the pH is higherpH = 10 Basis for litmus paper and other acid/base indicators

Table M – Shows the approximate color change for some common indicators bromthymol blue – Example –1. If thymol blue is yellow and bromcresol green is blue, what could the pH be? Bromthymol blue - _________________________ Methyl orange - ___________________________ Litmus -Red if pH is below 5.5, and blue if above 8.2 changes from yellow to blue if the pH changes from below 6 to above If a solution contains 1.0 x M of hydrogen ions, what color will the following indicators be? Thymol blue – below 8 Bromcresol green – above 5.4 Between 5.4 and 8 If [H + ] is 1 x M, pH is 5 yellow

Naming acids and bases 1. Binary Acids – only contain two elements - HX where X is some nonmetal hydro/ stem / ic acid prefixsuffix Ex. HF HBr H2SH2S Hydrofloric acid Hydrobromic acid Hydrosulfic acid 2. Ternary Acids- Have more than two elements ( polyatomic ions ) - ate radicals  ic acid - ite radicals  ous acid Ex. H 2 SO 4 - H 2 SO 3 - HNO 2 Sulfuric acid Sulfous acid Nitrous acid

Salts are ionic compounds - they contain cations and anions They are strong electrolytes - They will dissociate easily in water In a neutralization reaction To find the salt formed from a neutralization, cross out the H’s in the acid and cross out the OH in the base Determine the salt formed when the following acids and bases are mixed. C. NaOH + H 2 SO 4 B. NH 4 OH + HCl A. KOH + HNO 3 KNO 3 NH 4 Cl Na 2 SO 4 D. Ca(OH) 2 + HBr CaBr 2 Acid + Base Salt + Water