Chem 120 Acids and Bases

Views:
 
Category: Education
     
 

Presentation Description

Chem 120 Acids and Bases

Comments

By: siddhu.kadam22 (16 month(s) ago)

respected sir this is very nice presentation please send me this presentation at kadamsiddhu@yahoomail.com

By: eidalaa (20 month(s) ago)

Dear sir, this is Very nice presentation, kindly send it to me eidalaa@gmail.com is my email address.

By: dhruvdeka (22 month(s) ago)

moo impressed. good representation.

By: daiphu (29 month(s) ago)

Very good preparation for our students, our future

By: bhavjot (44 month(s) ago)

Very nice presentation

Presentation Transcript

Slide 1: 

Chapter 07 ACIDS AND BASES

Slide 2: 

Arrhenius Acid: A substance that dissociates in water to produce hydrogen ions, H1+. Arrhenius Base: A substance that dissociates in water to produce hydroxide ions, OH1-. Acid-Base Theory

Slide 3: 

Brønsted-Lowry Acid: A substance that can transfer hydrogen ions, H1+. In other words, a proton donor. Brønsted-Lowry Base: A substance that can accept hydrogen ions, H1+. In other words, a proton acceptor. Acid-Base Theory

Slide 4: 

Properies of Acids and bases Properties of Acids Are generally sour in taste Strong or concentrated acids often produce a stinging feeling on mucous membranes Change the color of pH indicators as follows: turn blue litmus and methyl orange red, turn phenolphthalein colorless React with metals to produce a metal salt and hydrogen React with metal carbonates to produce water, CO2 and a salt React with a base to produce a salt and water React with a metal oxide to produce water and a salt Conduct electricity, depending on the degree of dissociation Produce solvonium ions, such as hydronium (H3O+) ions in water Acid-Base Properties of Water Water is amphiprotic. It can act both as an acid and a base.

Slide 5: 

Properies of Acids and bases Properties of Bases Bitter taste (opposed to sour taste of acids) Slimy or soapy feel on fingers, due to saponification of the lipids in human skin Concentrated or strong bases are caustic (corrosive) on organic matter and react violently with acidic substances Aqueous solutions or molten bases dissociate in ions and conduct electricity Reactions with indicators: bases turn red litmus paper blue and phenolphthalein red

Slide 6: 

Strong and Weak Acids and Bases Acid or base strength is a measure of the degree of dissociation of an acid or base in solution, independent of its concentration. Acids and bases are classified as strong when the reaction with water is virtually 100% complete and as weak when the reaction with water is much less than 100% complete. Strong Acids HCl HNO3 H2SO4 Weak Acids CH3COOH H2CO3 Strong Bases NaOH KOH Weak Bases NH3 C5H5N C6H5NH2 CH3NH2

Slide 7: 

Conjugate Acids and Bases A conjugate acid is the species formed when a base accepts a proton A conjugate base is the species formed when an acid donates a proton. The acid and base on the opposite sides of the equation are collectively termed a conjugate acid-base pair. Acids with the greatest proton-donating capability (strongest acids) have the weakest conjugate bases. Strong bases(good proton acceptors) have weak conjugate bases

Slide 14: 

Example 7.1 Write the conjugate acid of HS- Identify the stronger base, HS- or F- Identify the stronger acid, H2S or HF H2S HS- is the stronger base HF is the stronger acid Predicting Relative Acid-Base Strengths

Slide 15: 

Kw = [H3O1+][OH1-] Ion-Product Constant for Water: Dissociation of Water: Kw = (1.0 x 10-7)(1.0 x 10-7) = 1.0 x 10-14 at 25°C: [H3O1+] = [OH1-] = 1.0 x 10-7 M The Dissociation of Water

Slide 16: 

Kw = [H3O1+][OH1-] = 1.0 x 10-14 The Dissociation of Water

Slide 17: 

The Dissociation of Water

Slide 18: 

pH = -log[H3O1+] pH < 7 pH > 7 pH = 7 Basic solution: Neutral solution: Acidic solution: pH and pOH

Slide 19: 

Example 7.2 Calculate the pH of a 1.0 x 10 -3 M solution of HCl pH = 3.00 Calculating pH from Acid Molarity

Slide 20: 

Example 7.3 Calculate the [H3O]+ concentration of a solution of hydrochloric acid with pH = 4.00 [H3O]+ = 1.0 x 10-4 M Calculating [H3O]+ from pH

Slide 21: 

Example 7.4 Calculate the pH of a 1.0 x 10-5 M solution of NaOH. pH = 9.00 Calculating the pH of a Base

Slide 22: 

Example 7.5 Calculate the and [OH-] of a sodium hydroxide solution with pH = 10.00. [OH-] = 1.0 x 10-4 M Calculating Both Hydronium and Hydroxide Ion Concentrations from pH

Slide 23: 

Example 7.6 Calculate the pH of a sample of lake water that has a [H3O+] = 6.5 x 10-5 M pH = 4.19 Calculating pH with Non-integer Numbers

Slide 24: 

Example 7.7 The measured pH of a sample of lake water is 6.40. Calculate [H3O+]. [H3O+] = 3.98 x 10-7 M Calculating [H3O+] from pH

Slide 25: 

Acid-Base Indicator: A substance that changes color in a specific pH range. Indicators exhibit pH-dependent color changes because they are weak acids and have different colors in their acid (HIn) and conjugate base (In1-) forms. Color B Color A Tools for Measuring pH

Slide 26: 

Tools for Measuring pH

Slide 30: 

Reaction Between Acids and Bases The reaction of an acid with a base to produce a salt and water is referred to as neutralization. A neutralization reaction may be used to determine the concentration of an unknown acid or base solution. The technique of titration involves the addition of measured amounts of a standard solution (one whose concentration is known with certainty) to neutralize the second (solution with unknown concentration)

Acid-Base Titration : 

Acid-Base Titration Titration Is a laboratory procedure used to determine the molarity of an acid. Uses a base such as NaOH to neutralize a measured volume of an acid. Base (NaOH) Acid solution

Indicator : 

Indicator An indicator Is added to the acid in the flask. Causes the acid solution to change color when the acid is neutralized.

End Point of Titration : 

End Point of Titration At the end point, The indicator has a permanent color. The volume of the base used to reach the end point is measured. The molarity of the acid is calculated using the neutralization equation for the reaction.

Calculating Molarity from A Titration with A Base : 

Calculating Molarity from A Titration with A Base What is the molarity of an HCl solution if 18.5 mL of a 0.225 M NaOH are required to neutralize 10.0 mL HCl? HCl(aq) + NaOH(aq) NaCl(aq) + H2O(l) STEP 1 Calculate the moles of base. 18.5 mL NaOH x 1 L x 0.225 mole NaOH 1000 mL 1 L = 0.00416 mole NaOH

Calculating Molarity (continued) : 

Calculating Molarity (continued) STEP 2 Calculate the moles of HCl. HCl(aq) + NaOH(aq) NaCl(aq) + H2O(l) 0.00416 mole NaOH x 1 mole HCl 1 mole NaOH = 0.00416 mole HCl STEP 3 Calculate the molarity of HCl. 10.0 mL HCl = 0.010 L HCl 0.00416 mole HCl = 0.416 M HCl 0.0100 L HCl