Acids/Bases/ch 15
This presentation is the property of its rightful owner.
Sponsored Links
1 / 52

Acids/Bases/ch 15 PowerPoint PPT Presentation


  • 35 Views
  • Uploaded on
  • Presentation posted in: General

Acids/Bases/ch 15. Acid/base. Electrolyte—any substance which will form ions in solution and conduct electricity Three classes of electrolytes: A) Acids B) Bases C) Salts. Acid/Base. Properties of Acids: A) taste sour B) turn litmus red C) clear in phenolphthalein

Download Presentation

Acids/Bases/ch 15

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Acids bases ch 15

Acids/Bases/ch 15


Acid base

Acid/base

  • Electrolyte—any substance which will form ions in solution and conduct electricity

  • Three classes of electrolytes:

  • A) Acids

  • B) Bases

  • C) Salts


Acid base1

Acid/Base

  • Properties of Acids:

  • A) taste sour

  • B) turn litmus red

  • C) clear in phenolphthalein

  • D) react with water to form H3O+

  • E) react with metals to form H2 gas


Acid base2

Acid/Base

  • Strong acids—dissociate in water to form many ions “go to completion”. Have high Ka

  • Ex: HCl(aq) + H2O  H3O+(aq) + Cl-(aq)

  • Only 6 strong acids exist:

  • HCl HBr HI HNO3

  • HClO4 H2SO4

  • Show the dissociation on the board for each.


Acid base3

Acid/Base

  • Monoprotic acids---acids with only one hydrogen to ionize

  • HCl, HBr, HI, HF, HNO3, HClO4,CH3COOH


Acid base4

Acid/Base

  • Diprotic acids—those with 2 “H” to ionize

  • H2SO4 and H2CO3


Acid and base

Acid and Base

  • Triprotic Acids—those with 3 “H” to ionize

  • H3PO4

    Polyprotic acids---those with more than one “H” to ionize


Acid base5

Acid/Base

  • Binary acids---those with only two elements

  • Ternary acids—those with “3” elements


Acid base6

Acid --Base

  • Weak acids---- those which do NOT dissociate completely in water/

  • Equilibrium is reached ()

  • HF(aq) + H2O  H3O+(aq) + F-(aq)

  • Or

  • CH3COOH(aq) + H2O  H3O+(aq) + CH3COO-(aq)


Acid base7

Acid/Base

  • Properties of Bases:

  • A) taste bitter

  • B) turn litmus blue

  • C) turn pink in phenolpthalein

  • D) release OH- in solution

  • E) feel slippery to the touch

  • F) forms alkaline solutions


Acid base8

Acid -base

  • Strong bases---dissociate completely in water

  • Strong bases are: bases with cations from groups 1 or 2

  • ex: NaOH, KOH, LiOH, Ca(OH)2, Mg(OH)2


Acid base9

Acid/Base

  • Ex:

  • NaOH(aq) Na+(aq) + OH-(aq)

  • Ca(OH)2(aq)  Ca+2(aq) + 2OH-(aq)

  • ********note that when strong bases dissociate all OH- are released


Acid base10

Acid/Base

  • Weak bases—dissociate only a small amount and few ions form. Equilibrium is reached ()

  • NH4OH(aq)  NH4+(aq) + OH-(aq)

    or

    Al(OH)3(aq)  Al+3(aq) + 3OH-(aq)


Acid base11

Acid/Base

  • Neutralization: (double replacement)

  • Acid + base => water + salt

  • HCl + KOH => HOH + KCl

  • Write the balanced equation for?

  • Sulfuric acid reacts with calcium hydroxide


Acid base12

Acid/Base

  • Acids will always form the hydronium ion

  • (H3O+) when put into water.

  • Draw the structural formula on board

  • Structural formula shows bonding and where each atom is located in the molecule.


Acid base13

Acid/Base

  • Three classes of Acids and Bases:

  • A) Arrhenius

  • B) Bronsted-Lowry

  • C) Lewis


Acid base14

Acid/Base

  • Arrhenius:

    • Acid: releases H+ into solution (HBr, HCl, etc)

    • Base: releases OH- into solution (KOH, NaOH,etc)


Acid base15

Acid/Base

  • Bronsted-Lowry:

  • Acid: a proton donor

  • Base: a proton acceptor

  • HCl(aq) + H2O  H3O+(aq) + Cl-(aq)

  • (Cl-) is the spectator ion ( does NOT participate in reaction)


Acid base16

Acid/Base

  • H2SO4(aq) + H2O => H3O+(aq) + HSO4-(aq)

  • What is the spectator ion?


Acid base17

Acid -Base

  • Conjugate base: of an acid is the part that remains after a proton has been released

  • (always a product)

  • HF + H2O => H3O+ + F-

  • F- is the conjugate base

  • Demo on the board


Acid base18

Acid- Base

  • Conjugate acid- of a base is formed when the base accepts the proton from the acid

  • ( always a product)

  • H3O+ is the conjugate acid of the previous reaction

    H2SO4 + H2O => H3O+ + HSO4-

    acid base c. acid c. base


Acid base19

Acid/Base

  • A B

  • HI_____

  • CH3COOH ______

  • H3O+ _______

  • ______ OH-

  • ______ HSO4-


Acid base20

Acid-Base

  • Lewis :

  • acid: an e- pair acceptor

  • base: an e- pair donor

  • BF3 + NH3 => F3BNH3

  • Demo on board


Acid base21

Acid/Base

  • Amphoteric: substance which acts as an acid or a base ex: water

  • Demo on board

  • hydrochloric acid + water =>

  • ammonia + water =>


Acid base22

Acid/Base

  • Anhydrous: Without water

  • Acidic anhydride---an oxide that will produce an acid when added to water

  • carbon dioxide + water => carbonic acid

  • Basic anhydride—an oxide that will produce a base when added to water

  • sodium oxide + water => sodium hydroxide


Ph scale

pH Scale

  • Acid or base ?

  • pH scale is from 0-14

  • less than 7 ----acid

  • Greater than 7---basic

  • pH 7 ---neutral

  • Pure water is neutral


Ph scale1

pH Scale

  • Acid /base indicators can be used to determine if a solution is an acid or a base. Acid base

  • Litmus red blue

  • Phenolphthalein clear pink

  • Phenol red yellow green

  • Different indicators will work at different pH levels


Acid base23

Acid/Base

  • Phenolphthalein works best between 8.5 and 10.

  • Could you use Phenolphthalein on a solution with pH 6.5 ? Why? Why not?


Acid base24

Acid/Base

  • Pure water will ionize only a small amount.

  • ( it will be at equilibrium)

  • HOH(l) H+(aq) + OH-(eq)

  • K(eq) = [H+][OH-]

  • Since it takes 107 liters of water to form 1 mole of hydroxide ion and 1 mole of hydrogen ion, its Molarity is 1Mol/107liters

  • M = 1 X 10-7 for each ion


Acid base25

Acid/Base

  • The special equilibrium for water is :

  • Kw = [H+][OH-]

  • Kw = [ 1x 10-7][ 1 x 10-7]

  • Kw = 1 X 10 -14

  • Kwalways = 1 x10-14

  • ******note H+ is the same as H3O+


Acid base26

Acid – Base

  • [H+] = [OH-] in pure water

  • If you know the [ ] of the H+ you can calculate the [ ] of the OH- and vice versa


Acid base27

Acid-base

  • Ex: What is the [OH-] in a solution of .25M hydrochloric acid .

  • Step one: determine if acid is strong

  • Step two: write hydrogen ion concentration in exponential form

  • Step three: use Kw to solve the problem

  • Kw = [H+][OH-]

  • 1 x 10-14 = [ 2.5 x 10-1] [ OH-]

  • [OH-] = 1 X 10-14/ 2.5 X 10-1

  • [OH-] = 4 X 10 -14


Acids bases ch 15

  • What is the [H3O+] in a .004 M NaOH solution. Is this an acidic or basic solution?


Acids bases ch 15

  • What is the [OH -] in a .50M solution of HNO3 solution?


Acid base28

Acid - Base

  • Demo on the board

  • Page 541 (1-4)


Acids bases ch 15

pH

  • pH can be calculated from the [H+]

  • pH = -log[H+]

  • Ex: What is the pH of a solution with:

  • [H3O+] = 1 X 10-3

  • pH = -log(1 X 10-3)

  • pH = -1(-3)

  • pH = 3

  • Demo on calculator


Acids bases ch 15

pOH

  • pOH = -log [OH-]

  • What is the pOH of a solution that is .0001 M sodium hydroxide?

  • Sodium hydroxide is a strong base so it ionizes completely.

  • [OH-] = 1 X 10 -4

  • pOH = -log ( 1 X 10-4)

  • pOH = -1(-4)

  • pOH = 4


Ph and poh

pH and pOH

  • pH + pOH = 14


Acids bases ch 15

pH

Calculate the pH of the following:

a) [H+] = 3.0 X 10-8

b) [OH-] = 4.0 X 10-6

c) [H3O+] = 8.2 X 10-6

Determine for each example if it is acid, base, or neutral.


Acids bases ch 15

pH

  • True or false:

  • As the [H3O+] increases the pH increases.

  • As the solution becomes more basic the [OH-] increases

  • As the pH increases the [OH-] increases

  • In pure water [H+] = [OH-]


Titrations

Titrations

  • Acid-base titration—process in which a neutralization reaction is used to determine the concentration of a solution with unknown molarity.


Titrations1

Titrations

  • An acid base indicator showing the color change at the “end point” will be used.

  • End point—point in the titration in which the color of the solution changes

  • Equivalence point---the point at which the amount of acid will neutralize the base. Mols of [H+] = mols of [OH-]


Titration

Titration

  • Titration curves:

  • Strong acid titrated with strong base (p551)

  • Weak acid titrated with strong base

  • Strong acid titrated with weak base

  • Plateau of each curve represents the part of the titration in which the hydrogen ion is neutralizing the hydroxide ion.


Titrations2

Titrations

  • Solving titration problems:

  • VaMa = VbMb

    What is the molarity of a NaOH solution if 40.0 ml of the solution is neutralized by 35.6 ml of .24 M solution of HBr.

    VaMa = VbMb

    35.6 ml x .24 M = 40.0ml X Mb

    Mb = .21 M


Acids bases ch 15

  • How many milliliters of .005 M KOH is needed to neutralize 50 ml of .05M HNO3?


Acids bases ch 15

  • Performing a titration page 552 and 553


Acids bases ch 15

  • Buffer solutions: solutions which resist changes in pH

  • Blood needs to have pH from 7.35 to 7.45.

  • If below 7.35 you suffer acidosis

  • If above 7.45 you suffer alkalosis


Acids bases ch 15

  • Acidosis: blood overwhelmed with too much acid ( leg cramps after exhausting excerise)

  • Alkalosis: blood has too little acid. ( hyperventilation ---body loses too much CO2)


Acids bases ch 15

  • Buffer solution : is made from a WEAK acid and its conjugate base. This will neutralize the change in pH.

  • If the solution is “buffered” the addition of a small amount of acid or base will NOT change the pH


Salts

Salts

  • Salt—an ionic compound composed of the cation of the base and the anion of the acid. May be soluble or insoluble.

  • Old book page 920---table

    ex: sulfuric acid reacts with calcium hydroxide.

  • Write the balanced equation

  • Classify the reaction

  • Name the salt

  • Determine if the salt is soluble or insoluble


Salts1

Salts

  • Aluminum hydroxide reacts with nitric acid.

  • Write the balanced equation

  • Name the salt

  • Is the salt insoluble or soluble


Review

Review

  • Pp 566-567

  • # 1-2

  • #4-9

  • #11

  • #14-19

  • # 25

  • #29

  • #40-45


  • Login