Binary acids – use the prefix “hydro” + the name of the negative (second ion), changing the en...
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HCl (aq)hydrochloric acid HBr (aq)hydrobromic acid HI (aq)hydroiodic acid PowerPoint PPT Presentation


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Binary acids – use the prefix “hydro” + the name of the negative (second ion), changing the ending to “-ic acid”. Oxy-acids – Name the polyatomic ion, change the ending to either “-ic acid” or “-ous acid” according to the “ate = ic, ite = ous” rule. HCl (aq)hydrochloric acid

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HCl (aq)hydrochloric acid HBr (aq)hydrobromic acid HI (aq)hydroiodic acid

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Hcl aq hydrochloric acid hbr aq hydrobromic acid hi aq hydroiodic acid

Binary acids – use the prefix “hydro” + the name of the negative (second ion), changing the ending to “-ic acid”.Oxy-acids – Name the polyatomic ion, change the ending to either “-ic acid” or “-ous acid” according to the “ate = ic, ite = ous” rule.

  • HCl (aq)hydrochloric acid

  • HBr (aq)hydrobromic acid

  • HI (aq)hydroiodic acid

  • HF (aq)hydrofluoric acid

  • H2S (aq)hydrosulfuric acid

  • H2SO4sulfuric acid

  • H2SO3sulfurous acid

  • H3PO4phosphoric acid

  • H3PO3phosphorous acid

  • HNO3nitric acid


Acids and bases

Acids and Bases


What is an acid base

What is an Acid? Base?

  • What do you think and acid is?

  • What do you think a base is?


Properties of acids and bases

Properties of Acids and Bases!

  • Acids have specific properties

    • Sour taste

    • pH beow 7.00 S.U.

    • Turn litmus paper red

    • Dissolve metals

  • Bases have similar properties

    • Bitter taste

    • pH above 7.00 S.U.

    • Feel slippery

    • Turn litmus paper blue


What else can they do

What else can they do?

  • Acids and bases neutralize each other

    • In other words, they raise/lower the pH to a non-acid/non-base

  • Acids and Bases can both destroy human tissue


How do they do that

How do they do that?

  • Acids and bases are electrolytes

    • The ions that they produce give them their properties


Strength of acids

Strength of Acids

  • A strong acid is one that dissolves completely in solution.

    • A weak acid is one that does not dissolve completely.

  • Why would an acid not dissolve completely?


Do you know any acids or bases

Do you know any acids or bases?

  • List some common acids and bases

    • Vinegar is Acetic Acid

    • Ammonia is a Base

    • Sodium Bicarbonate (Baking soda) is a Base

    • Batteries contain Sulfuric Acid

    • Your stomach contains Hydrochloric Acid!


There are more than one

There are more than one

  • There are 3 different types of acids and bases

    • Arrhenius

    • Brönsted-Lowry

    • Lewis


Arrhenius acids and bases

Arrhenius Acids and Bases

  • An Arrhenius Acid is a substance that releases H3O+ ions in an aqueous solution

    • HCl H2O H3O+ + Cl-

  • An Arrhenius Base is a substance that releases –OH in an aqueous solution

    • NaOH H2O Na+ + OH-


Br n sted lowry acids and bases

Brönsted-Lowry Acids and Bases

  • A Brönsted-Lowry acid is any species that can donate a proton (H+ ion) to another species; a proton donor

  • A Brönsted-Lowry base is any speices that can accept a proton (H+ ion) from another species; a proton acceptor


Hcl h 2 o h 3 o cl

HCl + H2O  H3O+ + Cl-

  • Which is the Brönsted-Lowry acid/base?

    • Acid is the proton donator

    • Base is the proton acceptor

    • HCl is the acid

    • H2O is the base


Water acid or base

Water: Acid or Base?

  • Take a look at these two reactions

    1. NH3 + H2O  NH4++ OH-

    2. HCl + H2O  H3O++ Cl-

  • In reaction #1, which is the B-L acid? Base?

    • Water is the acid and ammonia is the base

  • In reaction #2?

    • HCl is the acid and water is the base


Amphiprotic

Amphiprotic

  • A compound that can be both a proton donor OR a proton acceptor in separate reactions is called amphiprotic or amphoteric


Lewis acids and bases

Lewis Acids and Bases

  • A Lewis Acid is any species that can accept a pair of electrons from another species; electron pair acceptor

  • A Lewis Base is any species that can donate a pair of electrons from another species; electron pair donor


Remember lewis structures

Remember Lewis Structures!

  • Let’s look at a few examples

    H+H+ is an electron pair acceptor

    :Ö-H-OH- is an electron pair donor

    :Ö-HLewis acid-base product

..

H

..


Compare the definitions

Compare the Definitions


Acid base equilibria

Acid-Base Equilibria

  • In a chemical reaction involving both acids and bases, dynamic equilibrium can still be achieved

  • A species that is an acid in the forward direction, can become the base in the reverse direction


Hno 2 h 2 o h 3 o no 2 acid base acid base

HNO2 + H2O  H3O+ + NO2-acid baseacidbase

  • Let’s take a look at this reaction

    • HNO2 donates a proton in the forward reaction and is therefore a B-L acid

    • H2O accepts a proton in the forward reaction and is the B-L base

    • In the reverse direction, H3O+ donates a proton; B-L acid

    • And NO2- accepts a proton; B-L base


Conjugate pairs

Conjugate Pairs

  • When an acid donates a proton, it becomes a conjugate base

  • When a base accepts a proton, it becomes a conjugate acid

  • Why?

    • The acid-base reaction can be a reversible reaction and so when you move in the opposite direction, the compounds are redefined as acids and/or bases


Conjugates

Conjugates

  • For example, look at the following reaction

    HCl + H2O  H3O+ + Cl-

  • Which reactant is the acid? The base?

  • Now, in the reverse direction, which product is the acid? The base?

  • Now, what are the conjugate pairs?


Conjugates some more

Conjugates, some more

  • Look at this reaction:

    NH3 + H2O  NH4+ + OH-

  • Which reactant is the acid? The base?

  • Now, in the reverse direction, which product is the acid? The base?

  • Now, what are the conjugate pairs?


Conjugate practice

Conjugate Practice

  • What are the conjugate pairs for the following reactions?

    • HNO3 + OH-  H2O + NO3-

      • HNO3 is the acid and NO3- is the conjugate base

      • OH- is the base and H2O is the conjugate acid

    • H2SO4(aq) + SO32-(aq)  HSO4-(aq) + HSO3-(aq)

      • Sulfuric acid is the acid and HSO4- is the conjugate base

      • Sulfite ion is the base and HSO3- is the conjugate acid


Strength

Strength

  • If a acid is strong, then the conjugate base is weak and vice-versa


Strong weak electrolytes

Strong/Weak Electrolytes

  • An electrolyteis a solution that will conduct an electrical current.

  • Any ionic compound that dissociates in solution will conduct electricity.

  • If a substance dissociates 100%, it is called a strongelectrolyte.

  • A weak electrolyte dissociates < 100% (usually < 5%)


Strong acids

Strong Acids

  • Binary acids:

    • HCl, HBr, and HI are strong acids. All other binary acids are weak.

  • Oxy acids:

    • If the number of oxygen atoms exceed the number of hydrogen atoms by 2 or more, the acid is strong.


Strong bases

Strong Bases

  • Hydroxides made from metals in group 1 or group 2 are strong bases.

  • All other hydroxides are weak bases.


Molecular structure and the strength of acids

Molecular Structure and the Strength of Acids

  • The strength of an acid depends on a number of factors, such as the properties of the solvent, the temperature, and the molecular structure of the acid.

  • We compare the strengths of two acids, in the same solvent and at the same temperature. That way we can focus on the structure of the acid.


Binary hydrides

Binary Hydrides

  • HA ---> H+ + A-

  • Two factors influence the extent to which the acid undergoes ionization.

  • One is the strength of the H-A bond

    • the stronger the bond, the more difficult it is for the HA molecule to break up and hence the weaker the acid.


Polarity versus strength

Polarity versus Strength

  • The other factor is the polarity of the H-A bond.

    • The difference in electronegativities between H and A results in a polar bond.

    • If the bond is highly polarized, it is a stronger acid.


Hydrohalic acids

Hydrohalic Acids

  • The halogens form a series of binary acids called the hydrohalic acids.

  • The strengths of the hydrohalic acids increase in the following order:

    • HF<<HCl<HBr<HI


Other non metallic acid strengths

Other Non-metallic Acid Strengths

  • In any vertical column (Group) of nonmetallic elements, there is a tendency toward increasing acidity of the hydride with increasing atomic number (as you go down the group).

  • For example, among the group VIA elements the acid strength increases in the order:

    • H2O< H2S<H2Se<H2Te


Oxyacids

Oxyacids

  • Many common acids contain one or more O-H bonds.


Hcl aq hydrochloric acid hbr aq hydrobromic acid hi aq hydroiodic acid

Practice Problems

  • HF

  • weak

  • H2S

  • weak

  • H2SO4

  • strong

  • H2CO3

  • weak

  • Fe(OH)3

  • weak

6.Barium hydroxide

strong

7.Chloric acid

strong

8.Sulfurous acid

weak

9.Hypochlorous acid

weak

10.Tin(IV) hydroxide

weak

Ba(OH)2

HClO3

H2SO3

HClO

Sn(OH)4


Review

Review

  • In the following equations, name the acid and base. What was your justification?

    • NH3 + H2O  NH4+ + OH-

    • 2NaBr + H2SO4  Br2 + SO2 + 2NaOH


Review1

Review

  • What is the difference between a strong acid and a weak acid?

  • A buffer is a solution made from a weak acid and it’s conjugate base that neutralizes a small amount of acids or bases added to it


Calculating ph

Calculating pH


Hcl aq hydrochloric acid hbr aq hydrobromic acid hi aq hydroiodic acid

pH

  • pH is a measure of how acidic, neutral or basic a solution is

  • The scale for pH is 0-14

    • 7 is neutral

    • 0-7 is acidic

    • 7-14 is basic


The numbers mean

The Numbers mean . . .

  • pH + pOH = 14 S.U.

  • pH = -log10[H3O+]

  • pOH = -log10[OH-]


What is ph

What is pH?

  • The term pH refers to a scale that describes how strongly acidic or basic a solution is

    • pH + pOH = 14

    • Acidic = 0-7

    • Neutral = 7

    • Basic = 7-14


The k w constant

The Kw Constant

  • Kw = 1.0 x 10-14

    • at standard thermodynamic temperature (25oC or 298 K)


Ionization constants of acids and bases

Ionization Constants of Acids and Bases

  • HA(aq) + H2O(l) ↔ H3O+(aq) + A-(aq)

  • Keq= [H3O+][A-] / [HA][H2O]

  • In a dilute solution, the concentration of water is constant, so

    • Keq= [H3O+][A-] / [HA]


Ionization constants

Ionization Constants

  • The Ionization Constant for water; Kw is derived as follows:

  • First: for the acids

    HA(aq) + H2O(l)  H3O+(aq) + A-(aq)

    Keq = Ka = [H3O+][A-] / [HA]


Now the bases

Now the bases . . .

B(aq) + H2O(l)  BH+(aq) + OH-(aq)

Keq = Kb = [BH+][OH-] / [B]


Combine the two

Combine the two

HA(aq) + H2O(l)  H3O+(aq) + A-(aq)

Keq = Ka = [H3O+][A-] / [HA]

&

B(aq) + H2O(l)  BH+(aq) + OH-(aq)

Keq = Kb = [BH+][OH-] / [B]

=

Kw= [H3O+][OH-]


Calculations

Calculations

  • Problem:

    What are the hydronium and hydroxide ion concentrations in a 0.10M HCl?

    HCl(aq) + H2O(l)  H3O+(aq) + Cl-(aq)

    Kw = [H3O+][OH-]

    1.0 x 10-14 = (0.1M) x [OH-]

    [OH-] = 1.0 x 10-13


Calculating ph1

Calculating pH

  • A pH is equal to the -log10 of the Hydronium ion concentration

    pH = -log10[H3O+]

  • If an acid has a [H3O+] of 1.0 x 10-2M; then the pH is 2 S.U.

  • S.U. = standard unit


Calculating h 3 o

Calculating [H3O+]

  • The concentration of Hydronium ions can be determined by the reverse calculation, sort of

    • If the pH of a solution is 5.05 S.U., then the concentration of [H3O+] is 10-pH.

    • 5.05 S.U. = 10-5.05 = 8.9 x 10-6 M


Tricks

Tricks

  • If your concentration is 1.0 x 10-10 M, then your pH will be 10 S.U.!

    • The negative exponent becomes the pH

  • If your concentration is greater than 1.0, then the pH will be less than the negative exponent.

    • 2.5 x 10-10 M = >10 S.U. = 9.6

  • This comes in handy when you are answering multiple choice questions about the pH of a solution.


Practice problems

Practice Problems

  • What is the pH of a solution if the [H3O+] is 5.0 x 10-3M?

  • What is the pH of a solution if the [OH-] is 2.0 x 10-3M?

  • What is the [H3O+] of a solution whose pH is 3.3?

  • What is the [OH-] of a solution whose pH is 8.1?


Arrhenius neutralization reaction

Arrhenius Neutralization Reaction

  • An Arrhenius acid-base reaction looks something like this (does it kind-a look familiar?

    HCl + NaOH

    HCl + NaOH  H2O + NaCl


Neutralization reactions

Neutralization Reactions

  • Any acid-base reaction is called a neutralization reaction.

    • By products are always a salt, water (or a gas). Heat is also generated

    • These reactions can be violent


Predict the products

Predict the Products

  • HNO3 + KOH 

    • KNO3 + HOH

  • HBr + NH4OH 

    • NH4Br + HOH

  • H3PO4 + Ca(OH)2 

    • Ca3(PO4)2 + HOH

  • H2SO3 + LiOH 

    • Li2SO3 + HOH


How do you measure ph

How do you measure pH?

  • Litmus Paper

  • Color change indicator

  • pH meter


Compare the scale

Compare the Scale


Acid base indicators

Acid & Base Indicators

  • Acid and Base indicators are substances that change color in response to a specific pH

  • Different indicators are used depending on the range of the sample


Comparison chart

Comparison Chart

Which of these indicators can be used to distinguish between a solution whose pH is 4.6 S.U. and one that is 7.9 S.U.?

Look at the chart. Only Bromothymol blue can distinguish between the two solutions.


Comparison chart1

Comparison Chart

Which indicators can be used to distinguish between Soln. A: pH = 2.0 and Soln. B pH = 5.0?

Methyl orange


Comparison chart2

Comparison Chart

Which indicators can be used to distinguish between Soln. A: pH = 5.0 and Soln. B pH = 9.0?

Bromothymol blue or litmus


Titrations

Titrations

  • Titration The process, operation, or method of determining the concentration of a substance in a solution to which the addition of a reagent having a known concentration is made in carefully measured amounts until a reaction of definite and known proportion is completed, as shown by a color change or by electrical measurement, and then calculating the unknown concentration.

  • The equivalence point (end point) is reached when a titrant is added and is stoichiometrically equal to the amount of moles of substance (known as analyte) present in the sample; or, the smallest amount of titrant that is sufficient to fully neutralize or react with the analyte


Titrations1

Titrations

  • NaVa = NbVb

    • (look familiar?)

    • N is normality

    • N = M x n (the number of moles of H+ or OH- ions released into solution)

  • The titrant is usually the solution of known concentration that is delivered by a burette into a known quantity of the solution of unknown concentration

  • The titraver is the indicating solution


Naming acids

Naming Acids

  • Acids are formed when a Hydrogen is added to an anion

  • Take the anion root,

    • Add a hydro- in front

    • Change the ending from –ide or -ate to –ic; or from –ite to -ous

    • Put them all together and add the word “acid”


Hcl aq hydrochloric acid hbr aq hydrobromic acid hi aq hydroiodic acid

HCl

  • Take the anion root,

    • Add a hydro- in front

      • Hydro

    • Change the ending from –ide or –ate to –ic; or from –ite to -ous

      • chloride  chloric

    • Put them all together and add the word “acid”

      • Hydrochloric Acid


Acid base nomenclature

Acid/Base Nomenclature

  • Arrhenius Theory

    • Binary Acids:

      • Prefix = hydro--

      • Suffix = --ic

        Examples:

        HCl

        Hydrochloric acid

        HBr

        Hydrobromic acid


Acid base nomenclature1

Acid/Base Nomenclature

  • Arrhenius Theory

    • Oxy acids:

      H+combined with a polyatomic anion containing oxygen (P.178)

    • No prefix

    • If the name of the anion ends –ate, the acid ends –ic

    • If the name of the anion ends –ite, the acid ends -ous


Oxy acid examples

Oxy Acid Examples

Ion Acid

SO4-2

H2SO4

Sulfate

Sulfuric acid

NO3-

HNO3

Nitrate

Nitric acid

NO2-

HNO2

Nitrite

Nitrous acid

CO3-2

H2CO3

Carbonate

Carbonic acid


Acid base nomenclature2

Acid/Base Nomenclature

  • Arrhenius Theory

    • Bases:

      Name the hydroxide base.


Naming bases

Naming Bases

  • Bases are MUCH easier to name

  • Simply name the cation and anion

    • NaOH

    • Sodium hydroxide


Practice problems1

Practice Problems

  • HF

  • hydrofluoric acid

  • H2S

  • hydrosulfuric acid

  • H2SO3

  • sulfurous acid

  • NaOH

  • Sodium hydroxide

  • Fe(OH)3

  • Iron (III) hydroxide

6.Calcium hydroxide

Ca(OH)2

7.Chromic acid

H2CrO4

8.Phosphorous acid

H3PO3

9.Acetic acid

HC2H3O2

10.Hydroselenic acid

H2Se


Homework quiz p 538 1 13

Homework Quiz: p. 538 #1-13

  • What are the observable properties of an acid?

  • What is an Arrhenius definition of a base?

  • How does a strong acid differ from a weak acid?

  • How does the definition of a Bronsted-Lowry definition of an acid differ from that of the Arrhenius definition?


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