BRN – place these items in the T-chart AcidNeutralBase

Safety  WEAR goggles at ALL times!  Today we are working with HCl (Hydrochloric acid) CaCl 2 and NaOH which can irritate skin. If some gets on your skin rinse immediately with water.  Dispose of chemicals down sink.  WEAR goggles at ALL times!  Today we are working with HCl (Hydrochloric acid) CaCl 2 and NaOH which can irritate skin. If some gets on your skin rinse immediately with water.  Dispose of chemicals down sink.

Lab Activity- Part 1  Put small amounts of 12 different substances in the sample well plates.  Use a small sample of red, blue, and pH paper to dip into well plate and record observations  Put small amounts of 12 different substances in the sample well plates.  Use a small sample of red, blue, and pH paper to dip into well plate and record observations

Lab Activity- Part 2  Using the pH values that you found in part 1, place the substances on the pH scale.

Share Out!  Did the results of the lab activity surprise you?  Which substances are acids?  Which are bases?  What happened with neutral substances?  What were some of the color patterns you saw?  Did the results of the lab activity surprise you?  Which substances are acids?  Which are bases?  What happened with neutral substances?  What were some of the color patterns you saw?

Acid/Base Notes New Section in Table of Contents

What is an acid?

 KC 1: Properties of acids  Tart, sour taste  Conduct electricity well  React with many metals  Contain H + ion  Generate hydronium ions – H 3 O +  pH less than 7  Neutralizes bases  KC 1: Properties of acids  Tart, sour taste  Conduct electricity well  React with many metals  Contain H + ion  Generate hydronium ions – H 3 O +  pH less than 7  Neutralizes bases

How are acids measured?  KC 2: pH is a logarithmic scale that express the concentrations of hydrogen ions in aqueous solutions  pH = - log[H + ]  KC 2: pH is a logarithmic scale that express the concentrations of hydrogen ions in aqueous solutions  pH = - log[H + ]

pH Scale

Weak vs. Strong acids  KC 3: A strong acid fully dissociates into H + cations and its respective anion.  KC 4: Weak Acids do not ionize completely  Strong versus weak is not related to pH.  KC 3: A strong acid fully dissociates into H + cations and its respective anion.  KC 4: Weak Acids do not ionize completely  Strong versus weak is not related to pH.

Common Acids  HCl- hydrochloric- stomach acid  H 2 SO 4 - sulfuric acid - car batteries  HNO 3 – nitric acid - explosives  HC 2 H 3 O 2 - acetic acid - vinegar  H 2 CO 3 -carbonic acid – sodas  H 3 PO 4 - phosphoric acid - flavorings  HCl- hydrochloric- stomach acid  H 2 SO 4 - sulfuric acid - car batteries  HNO 3 – nitric acid - explosives  HC 2 H 3 O 2 - acetic acid - vinegar  H 2 CO 3 -carbonic acid – sodas  H 3 PO 4 - phosphoric acid - flavorings

What is a base?

 KC 5 Properties of Bases:  pH greater than 7  Feels slippery  Dissolves fats and oils  Usually forms OH - ions in solution  Neutralizes acids  Commonly used as cleaning products.  KC 5 Properties of Bases:  pH greater than 7  Feels slippery  Dissolves fats and oils  Usually forms OH - ions in solution  Neutralizes acids  Commonly used as cleaning products.

Weak vs. strong bases  Key Concept 6: A strong base fully dissociates into OH - anions and its respective cations.  Weak Bases: ammonia; potassium carbonate, sodium carbonate  Strong Bases: sodium hydroxide; sodium phosphate; barium hydroxide; calcium hydroxide  Strong versus weak is not related to pH.  base-solutions base-solutions  Key Concept 6: A strong base fully dissociates into OH - anions and its respective cations.  Weak Bases: ammonia; potassium carbonate, sodium carbonate  Strong Bases: sodium hydroxide; sodium phosphate; barium hydroxide; calcium hydroxide  Strong versus weak is not related to pH.  base-solutions base-solutions

Common Bases  NaOH- sodium hydroxide (LYE) soaps, drain cleaner  Mg (OH) 2 - magnesium hydroxide-antacids  Al(OH) 3 -aluminum hydroxide-antacids, deodorants  NH 4 OH-ammonium hydroxide- “ammonia”  NaOH- sodium hydroxide (LYE) soaps, drain cleaner  Mg (OH) 2 - magnesium hydroxide-antacids  Al(OH) 3 -aluminum hydroxide-antacids, deodorants  NH 4 OH-ammonium hydroxide- “ammonia”

Acids and Bases  KC 7: Arrhenius acid and base:  Acids increase H + cation concentration in water  Bases increase OH - anion concentration in water  KC 7: Arrhenius acid and base:  Acids increase H + cation concentration in water  Bases increase OH - anion concentration in water HCl(aq) + H 2 O(l)  H 3 O + (aq) + Cl - Increases H + Increases OH -

HCl(aq) + H 2 O(l)  H 3 O + (aq) + Cl - Loses a proton Gains a proton Acids and Bases  KC 8: Brønsted-Lowry acid and base:  Acids are proton (H+) donators  Bases are proton acceptors  KC 8: Brønsted-Lowry acid and base:  Acids are proton (H+) donators  Bases are proton acceptors

Conjugate Acid/Base  KC 9: Conjugate acid – an acid that forms when a base gains a proton  KC 10: Conjugate base – a base that forms when an acid loses a proton  KC 9: Conjugate acid – an acid that forms when a base gains a proton  KC 10: Conjugate base – a base that forms when an acid loses a proton AcidConjugate Acid Conjugate BaseBase

Acids and Bases  KC 11: Amphoteric – substance that has the properties of an acid and the properties of a base H 2 O (l) + H 2 O (l) ↔ H 3 O + (aq) + OH - (aq) AcidConjugate Acid Conjugate BaseBase

pH pH = -log [H + ]

pH is a measure of the number of hydronium ions 2H 2 O ↔ H 3 O + + OH -

pH Paper  pH paper changes color to indicate a specific pH value.

Indicators  Key Concept 12: Chemical dyes whose color are affected by acidic and basic solutions are called acid-base indicators.  Not all indicators show when the pH is 7.  Key Concept 12: Chemical dyes whose color are affected by acidic and basic solutions are called acid-base indicators.  Not all indicators show when the pH is 7.

Indicators  The following table can be used to see when each indicator should be used:

Natural Indicators  There are some natural indicators such as cabbage juice or hydrangeas.

Ionization of Water H 2 O + H 2 O ↔ H 3 O + + OH -  [H 3 O + ] = [OH - ] = 1.00 x  [H 3 O + ][OH - ] = K w = (1.00 x )(1.00 x ) = 1.00 x H 2 O + H 2 O ↔ H 3 O + + OH -  [H 3 O + ] = [OH - ] = 1.00 x  [H 3 O + ][OH - ] = K w = (1.00 x )(1.00 x ) = 1.00 x

Concentrations and Kw Solution[H 3 O + ][OH - ]Kw = [H 3 O + ] [OH - ] Pure water1.0 x x M strong acid1.0 x x x M strong acid1.0 x x x M strong base1.0 x x x M strong base1.0 x x x M strong acid2.5 x x x M strong base4.0 x x x

pH  KC 13: pH is based on the concentration of hydronium (H 3 O) (hydrogen, H + ) ions  KC 14: pH = -log[H 3 O + ] (pH = -log[H + ])  KC 15: pOH is based on the concentration of hydroxide (OH) ions  KC 16: pOH = -log[OH]  KC 13: pH is based on the concentration of hydronium (H 3 O) (hydrogen, H + ) ions  KC 14: pH = -log[H 3 O + ] (pH = -log[H + ])  KC 15: pOH is based on the concentration of hydroxide (OH) ions  KC 16: pOH = -log[OH]

pH  KC 17:  pH + pOH = 14  pH < 7 = acid  pH > 7 = base  pH = 7 = neutral  [H + ] [OH - ] = 1.0 x  KC 17:  pH + pOH = 14  pH < 7 = acid  pH > 7 = base  pH = 7 = neutral  [H + ] [OH - ] = 1.0 x

pOH scale: pOH pH

[OH] = 1.0x / [H + ] [H + ] = 1.0x / [OH - ] pOH= 14 - pH pH = 14 - pOH [H + ] = 10 -pH pH = -log[H + ] [H + ] [OH - ] pH pOH [OH - ] = 10 -pOH pOH = -log[OH-] PH/pOH to concentration conversion flowchart

Calculating pH/pOH  Example – calculate the pH of a solution containing 3 mol of HCl dissolved in 400mL of water.

Calculating pH/pOH  KC 18: A solution has a hydronium ion concentration of 6.7 x M, what is its pH?

Calculation Practice  KC 19: If the hydronium ion concentration of a solution is 1.63 x M, what is the hydroxide ion concentration?

Reactions Between Acids and Bases  Key Concept 20: A neutralization reaction is a reaction in which an acid and a base in an aqueous solution react to produce salt and water.neutralization reaction  Key Concept 21: A salt is an ionic compound made up of a cation from a base and an anion from an acid.salt  Composed of the negative ion of an acid and the positive ion of a base.  Key Concept 22: Neutralization is a double- replacement reaction.  Key Concept 20: A neutralization reaction is a reaction in which an acid and a base in an aqueous solution react to produce salt and water.neutralization reaction  Key Concept 21: A salt is an ionic compound made up of a cation from a base and an anion from an acid.salt  Composed of the negative ion of an acid and the positive ion of a base.  Key Concept 22: Neutralization is a double- replacement reaction.

Reactions Between Acids and Bases  A neutralization reaction is the reaction an acid with a base to produce salt and water HCl + NaOH → NaCl + H 2 O 2 NaOH + H 2 SO 4 → 2 H 2 O + Na 2 SO 4  A neutralization reaction is the reaction an acid with a base to produce salt and water HCl + NaOH → NaCl + H 2 O 2 NaOH + H 2 SO 4 → 2 H 2 O + Na 2 SO 4

Predicting Acid/Base Reactions  KC 23: Predict the products of the following reactions:  NaOH + H 3 PO 4 →  KOH + HF →  H 2 SO 4 + LiOH →  KC 23: Predict the products of the following reactions:  NaOH + H 3 PO 4 →  KOH + HF →  H 2 SO 4 + LiOH →

BeakerIndicatorBasic ColorAcidic Color pH Range 1 Universal Indicator purpleorange 10 to 4 2 Bromcresol green blueyellow-green5.4 to 3.8 3Methyl Redyellow Red6.2 to Bromthymol Blue blue Yellow7.6 to 6.0

Neutralization Reactions  KC 24: M 1 V 1 = M 2 V 2 can be used to calculate the volume and/or concentrations of neutralization reactions  KC 25: If 50.0mL of 1.00M HI is neutralizaed by 35.41mL of KOH, what is the molarity of the KOH solution?  KC 24: M 1 V 1 = M 2 V 2 can be used to calculate the volume and/or concentrations of neutralization reactions  KC 25: If 50.0mL of 1.00M HI is neutralizaed by 35.41mL of KOH, what is the molarity of the KOH solution?

Neutralization Reactions  KC 26: Titrations are a lab technique used to experimentally find and calculate the concentration of an unknown acid or base

Titrations  The volume of base added can then be graphed versus the pH to determine the equivalence point  The concentration of the acid can then be determined from M 1 V 1 = M 2 V 2  The volume of base added can then be graphed versus the pH to determine the equivalence point  The concentration of the acid can then be determined from M 1 V 1 = M 2 V 2

Titrations  KC 27: What is the molarity of sodium hydroxide if 20.0 ml of solution is neutralized by 28.0 ml of a 1.00 M solution of hydrochloric acid?

Titrations  KC 28: A base is reacted with an acid at a 1:1 ratio. If it took 23.5 mL of acid to react completely with 45.2 mL of 2.4M base what is the concentration of the acid?

Titrations  video video  video video