LECTURE 2 THEME: Acid-base equilibrium in biological systems. Buffer solutions. ass. prof. Ye. B. Dmukhalska.

Slides:



Advertisements
Similar presentations
Acids & Bases Chemistry. Ms. Siddall..
Advertisements

Acids, Bases, and Salts Chapter 19.
Acid and Base Equilibrium
Acids and Bases Part 2. Classifying Acids and Bases Arrhenius Acid ◦ Increases hydrogen ions (H + ) in water ◦ Creates H 3 O + (hydronium) Base ◦ Increases.
Acids & Bases Acids: acids are sour tasting
1 Acid-Base Properties of a Salt Solution  One of the successes of the Brønsted- Lowry concept of acids and bases was in pointing out that some ions can.
Acids and Bases: Theory Arrhenius theory of acids Arrhenius definition of an acid: any compound that contains hydrogen and produces H + (H 3 O + when.
Analytical Chemistry Acid-Base. Arrhenius Theory: H+ and OH- This theory states that an acid is any substance that ionizes (partially or completely) in.
Acid-Base Equilibria Acids and bases are some of the more commonly encountered chemicals Acids and Bases control composition of blood and cell fluids,
Acids, Bases, and Salts CHM 1010 PGCC Barbara A. Gage.
Chapter 16 Acids and Bases. Chapter 16 Table of Contents Acids and Bases 16.2Acid Strength 16.3Water as an Acid and a Base 16.4The pH Scale 16.5.
Chapter 15 Applications of Aqueous Equilibria. The Common-Ion Effect Common-Ion Effect: The shift in the position of an equilibrium on addition of a substance.
Lecture Notes Alan D. Earhart Southeast Community College Lincoln, NE Chapter 14 Aqueous Equilibria: Acids and Bases John E. McMurry Robert C. Fay CHEMISTRY.
Dr. Saidunnisa Professor of Biochemistry Acids, bases, conjugate acid base pairs, body buffers.
Acids and bases, pH and buffers
Acid-Base Titrations.
ACIDS AND BASES Topic Reactions of acids and bases Acids with metals Produces a salt and hydrogen gas Mg + 2HCl  MgCl 2 + H 2 Acids with carbonates.
11 IB Topic 8: Acids & Bases 8.1 Theories of Acids & Bases 8.1.1Define acids and bases according to the Brǿnsted- Lowry and Lewis theories Deduce.
Chemical calculations used in medicine part 2 Pavla Balínová.
JF Basic Chemistry Tutorial : Acids & Bases Shane Plunkett Acids and Bases Three Theories pH and pOH Titrations and Buffers Recommended.
Mullis Acids, Bases and Salts Acids give up hydrogen ions (H + ) in a water solution. Bases give up hydroxide ions (OH - ) in a water solution.
Acids, Bases and Salts Acids give up hydrogen ions (H+) in a water solution. Bases give up hydroxide ions (OH-) in a water solution. Mullis.
Chapter 10 Acids and Bases.
Acids and Bases Chapter 15. Acids Have a sour taste. Vinegar owes its taste to acetic acid. Citrus fruits contain citric acid. React with certain metals.
Chapter 18 Acids and Bases Acids Arrhenius Acid – a compound containing hydrogen that ionizes to produce hydrogen ions (H + ) in water Names: Hydrochloric.
Acid-base theory pH calculations
Acids and Bases  Arrhenius ◦ Acid:Substance that, when dissolved in water, increases the concentration of hydrogen ions. ◦ Base:Substance that, when dissolved.
Bronsted-Lowry acids and bases
Chapter 18 “Acids, Bases and Salts”
ATB Question of the Day Day
11 IB Topic 8: Acids & Bases 8.1 Theories of Acids & Bases 8.1.1Define acids and bases according to the Brǿnsted- Lowry and Lewis theories Deduce.
Acids and Bases.
Acids and Bases. What are acids and bases? Lemons, grapefruit, vinegar, etc. taste sour because they contain acids. Acid in our stomach helps food digestion.
Buffer solutions. ass. prof. I. R. Bekus. Plan 1.Ionization of water. 2.Acid-base theory. 3.Buffer solutions. 4.Buffer in blood.
1 Introduction to Acids and Bases The earliest definition was given by Arrhenius: An acid contains a hydrogen atom and dissolves in water to form a hydrogen.
Karaganda State Medical University. Chemistry department. Lecture on the topic:Lecture on the topic: The doctrine of the solutions. Buffered solutions.
Buffer solutions. Theoretic bases of electrochemistry. LECTERE 2 Lecturer: Dmukhalska Ye. B.
8 8-1 © 2003 Thomson Learning, Inc. All rights reserved General, Organic, and Biochemistry, 7e Bettelheim, Brown, and March.
1 Acids, Bases and PH. 2 Some Properties of Acids þ Produce H + (as H 3 O + ) ions in water (the hydronium ion is a hydrogen ion attached to a water molecule)
Experiment 24 Page 257 Dr. Scott Buzby Ph.D..  Learn about the concept of hydrolysis  Acids  Bases  Hydrolysis  Gain a familiarity with acid-base.
Acids and Bases Chapter 15. Acids Have a sour taste. Vinegar owes its taste to acetic acid. Citrus fruits contain citric acid. React with certain metals.
19.1 Acid-Base Theories> 1 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. 1. Lactic acid, HC 3 H 5 O 3, has one acidic hydrogen.
Bettelheim, Brown, Campbell and Farrell Chapter 9
Chapter 7 Acids and Bases. Arrhenius Definitions - Acids produce hydrogen ion in aqueous, and bases produce hydroxide ions. Brønsted-Lowry Definitions.
Chapter 19: Acids, Bases, and Salts
1 Acids and Bases - the Three Definitions 1. The Arrhenius Definition of an Acid 2. Acid strength and pK a 3. K a, pK a, pK b 4. polyprotic acids, pK a1,
Mullis Acids, Bases and Salts Acids give up hydrogen ions (H + ) in a water solution. Bases give up hydroxide ions (OH - ) in a water solution.
CMH 121 Luca Preziati Chapter 8: Acids and Bases Acid = produces H + An acid is a compound that: 1. Has H somewhere 2. Has the tendency (is capable) of.
15 Acids and Bases Contents 15-1 The Bronsted-Lowry Definitions 15-2 The Ion Product of Water, Kw 15-3 The pH and Other “p” Scales 15-4 Concentrations.
According to the Arrhenius concept, a base is a substance that produce OH - ions in aqueous solution. According to the Brønsted-Lowry model, a base is.
Strength of Acids Strength of an acid is measured by the extent it reacts with water to form hydronium ions (H 3 O + ). Strong acids ionize ~100% so pH.
Equilibrium – Acids and Bases. Review of Acids and Bases Arrhenius Theory of Acids and Bases ▫An acid is a substance that dissociates in water to produce.
Acids and Bases. Arrhenius Acid & Base Which beaker contains a base?
THEME: Acid-base equilibrium in biological systems. Buffer solutions.
Applications of Aqueous Equilibria
Arrhenius Acids and Bases Acid: Acid: A substance that produces H 3 O + ions in aqueous solution. Base: Base: A substance that produces OH - ions in aqueous.
ATB Question of the Day Day
Acid and base Iman AlAjeyan. Acid-Base Theory Acids in water solutions show certain properties. They taste sour and turn litmus paper red. They react.
Acid/Base Titration Dr. Hisham Ezzat Abdellatef Prof. of Analytical Chemistry Dr. Hisham Ezzat Abdellatef Prof. of Analytical Chemistry Clinical Pharmacy.
Solutions. Acid–base equilibrium in biological systems.
Ch 9: Acids, Bases and Salts Suggested Problems: 2, 6, 10, 12, 28-44, 82, , Bonus: 118.
© Houghton Mifflin Harcourt Publishing Company Acids 1.Aqueous solutions of acids have a sour taste. 2.Acids change the color of acid-base indicators.
CHAPTER 9 Acids & Bases General, Organic, & Biological Chemistry Janice Gorzynski Smith.
ACIDS AND BASES. Acids 1.Aqueous solutions of acids have a sour taste. 2.Acids change the color of acid-base indicators. 3.Some acids react with active.
Unit III - Acid/Base - Chapter 15
CHAPTER 7.
Chemistry 100 Chapter 14 Acids and Bases.
Acids and bases.
Acid Base Chemistry.
Descriptions & Reactions
Presentation transcript:

LECTURE 2 THEME: Acid-base equilibrium in biological systems. Buffer solutions. ass. prof. Ye. B. Dmukhalska

Electrolytes in Aqueous Solution Electrolytes are substances such as NaCl or KBr, which dissolve in water to produce conducting solutions of ions. Nonelectrolytes are substances such as sucrose or ethyl alcohol, which do not produce ions in aqueous solution.

Anode Cathode (negative electrode) Solution of NaCl

Anode Solution of NaCl Cathode

According to the Degree of dissociation (α) electrolytes can be classified into the following: strong electrolytes are compounds that dissociate to a large extent (α> 30%) into ions when dissolved in water. For example, HCl, H 2 SO 4, HNO 3, HJ, NaOH, KOH, KCl. Medium electrolytes α = %. For istance, H 3 PO 4, H 3 PO 3. weak electrolytes are compounds that dissociate to only a small extent α<2%. For example, NH 4 OH, H 2 S, HCN, H 2 CO 3. nonelectrolytes α = 0 are compounds that don’t dissociate when dissolved in water.

Acid–Base Concept 1)The Arrhenius theory ACID A substance that provides H+ ions in water BASE A substance that provides OH- ions in water

2) The Brønsted-Lowry Theory All Brønsted–Lowry bases have one or more lone pairs of electrons:

3) The Lewis Acids and Base theory LEWIS ACID An electron-pair acceptor LEWIS BASE An electron-pair donor

Dissociation of Water Water acts as both an acid and a base at the same time: This reaction is characterized by the equilibrium equation Kw = [H 3 O+] [OH - ] The equilibrium constant Kw is called the ion-product constant for water.

The pH of a solution is defined as the negative base-10 logarithm (log) of the molar hydronium H3O+ ion concentration: 5. Equilibria in Solutions of Weak Acids The dissociation of a weak acid in water is characterized by an equilibrium equation. The equilibrium constant for the dissociation reaction, denoted Ka is called the acid-dissociation constant: Values of Ka and pKa = - log Ka for some typical weak acids are listed in Table The larger the value of Ka, the stronger the acid

Equilibria in Solutions of Weak Bases Weak bases, such as ammonia, accept a proton from water to give the conjugate acid of the base and OH- ions: The equilibrium constant Kb is called the base-dissociation constant: Relation Between Ka and Kb

BUFFERS Buffers are solutions which can resist changes in pH by addition of acid or alkali.

the Henderson-Hasselbalch equation. for acidic buffer solution [А - ] рН = pК a + log [АH] -for basic buffer solution [В] рН = 14 - pК b + log [HВ + ]

Buffers are mainly of two types: (а) mixtures of weak acids with their salt with а strong base (b) mixtures of weak bases with their salt with а strong acid. А few examples are given below: Н 2 СО 3 / NаНСО 3 (Bicarbonate buffer; carbonic acid and sodium bicarbonate) СН 3 СООН / СН 3 СОО Na (Acetate buffer; acetic acid and sodium acetate) Na 2 HPO 4 / NaH 2 PO 4 (Phosphate buffer)

Composition of buffer solutions by Brønsted– Lowry theory : (a) weak acid with their conjugate base Н 2 СО 3 / НСО 3 - Bicarbonate buffer solution СН 3 СООН / СН 3 СОО - -Acetate buffer solution H 2 PO 4 - / HPO Phosphate buffer solution (b) weak base with their conjugate acid NН 3 / NH ammonia

Buffer solution of blood HHb/Hb - - Hemoglobin buffer solution HHbO 2 /HbO Oxihemoglobin buffer solution H 2 PO 4 - /HPO Phosphate buffer solution H 2 CO 3 /HCO 3 - ; - Bicarbonate buffer solution PtCOOH / PtCOO - or NH 2 -R-COOH / NH 2 -R-COO - - Protein buffer solution

Factors Affecting pH of а Buffer The pH of а buffer solution is determined by two factors: 1. The value of pK: The lower the value of pK, the lower is the pH of the solution. 2. The ratio of salt to acid concentrations: Actual concentrations of salt and acid in а buffer solution may be varied widely, with по change in рН, so long as the ratio of the concentrations remains the same.

Buffer Capacity On the other hand, the buffer capacity is determined by the actual concentrations of salt and acid present, as well as by their ratio. Buffering capacity is the number of grams of strong acid or alkali which is necessary for а change in pH of one unit of one litre of buffer solution. The buffering capacity of а buffer is, definеd аs the ability of the buffer to resist changes in pH when an acid or base is added.

Buffers Act When hydrochloric acid is added to the acetate buffer, the salt reacts with the acid forming the weak acid, acetic acid and its salt. Similarly when а base is added, the acid reacts with it forming salt and water. Thus, changes in the pH are minimised. СН 3 СООН + NaOH = СН 3 COONa + Н 2 О СН 3 СООNа + HCI = СН 3 СООН + NaCI The buffer capacity is determined by the absolute concentration of the salt and acid. But the рН of the buffer is dependent on the relative proportion of the salt and acid (see the Henderson - Hasselbalch's equation). When the ratio between salt and acid is 10:1, the pH will be one unit higher than the pKa. When the ratio between salt and acid is 1:10, the pH will be one unit lower than the pKa.

Mechanisms for Regulation of pH (1) Buffers of body fluids, (2) Respiratory system, (3) Renal excretion. These mechanisms are interrelated.