GENERAL CHEMISTRY 2024-2025 Liquid Mixture, Buffer Solution PDF

‫جامعة العين‬ ‫الكلية التقنية الصحية والطبية‬ ‫قسم تقنيات االشعة والسونار ‪-‬المرحلة االولى‬ ‫‪Liquid Mixture, Buffer Solution‬‬ ‫‪GENERAL CHEMISTRY 2024-2025‬‬ ‫‪Dr. Ahmed Jaber‬‬ ‫)‪Lec(2‬‬ ‫‪Dr. ahmed jaber‬‬ liquid mixture is a co...

‫جامعة العين‬ ‫الكلية التقنية الصحية والطبية‬ ‫قسم تقنيات االشعة والسونار ‪-‬المرحلة االولى‬ ‫‪Liquid Mixture, Buffer Solution‬‬ ‫‪GENERAL CHEMISTRY 2024-2025‬‬ ‫‪Dr. Ahmed Jaber‬‬ ‫)‪Lec(2‬‬ ‫‪Dr. ahmed jaber‬‬ liquid mixture is a combination of two or more substances where the individual components retain their chemical identity. These mixtures can be either homogeneous or heterogeneous. Types of Liquid Mixtures 1. Homogeneous Mixtures (Solutions): - The composition is uniform throughout. - Examples: Saltwater, alcohol in water, and vinegar. - Solvent: The component present in the largest amount. - Solute: The substance dissolved in the solvent. Dr. ahmed jaber 2.Heterogeneous Mixtures: - The composition is not uniform, and the components can be visually distinguished. - Examples: Oil and water, muddy water. Dr. ahmed jaber Properties of Liquid Mixtures  Miscibility: Determines whether two liquids can mix (e.g., water and ethanol are miscible, while oil and water are immiscible).  Boiling and Melting Points: Mixtures may have different boiling/melting points compared to their pure components due to interactions between molecules.  Concentration: Represents the amount of solute in a given quantity of solvent, expressed in terms like molarity or percentage. Dr. ahmed jaber Buffer Solution is a water solvent based solution which consists of a mixture containing a weak acid and its conjugate salt, or a weak base and its conjugate salt. They resist a change in pH upon dilution or upon the addition of small amounts of acid/alkali to them. Dr. ahmed jaber The pH of Buffer Solutions shows minimal change upon the addition of a very small quantity of strong acid or strong base. They are therefore used to keep the pH at a constant value. Types of Buffer Solution 1- Acidic Buffers : pH of these solutions is below seven These solutions consist of a weak acid and a salt of a weak acid. An example of an acidic buffer solution is a mixture of sodium acetate and acetic acid (pH = 4.75). Dr. ahmed jaber 2-Alkaline Buffers:- The pH of these solutions is above seven They contain a weak base and a salt of the weak base. An example of an alkaline buffer solution is a mixture of ammonium hydroxide and ammonium chloride (pH = 9.25). Dr. ahmed jaber Mechanism of Buffering Action In solution, the salt is completely ionized and the weak acid is partly ionized. CH3COONa ⇌ Na+ + CH3COO– CH3COOH ⇌ H+ + CH3COO– * On Addition of Acid and Base 1. On addition of acid, the released protons of acid will be removed by the acetate ions to form an acetic acid molecule. H+ + CH3COO– (from added acid) ⇌ CH3COOH (from buffer solution) 2. On addition of the base, the hydroxide released by the base will be removed by the hydrogen ions to form water. HO– + H+ (from added base) ⇌ H2O (from buffer solution) Dr. ahmed jaber Preparation of Acid Buffer Consider an acid buffer solution, containing a weak acid (HA) and its salt (KA) with a strong base(KOH). Weak acid HA ionizes, and the equilibrium can be written as- HA + H2O ⇋ H+ + A− Acid dissociation constant = Ka = [H+] [A–]/HA pH of acid buffer = pKa +log ([salt]/[acid]) Dr. ahmed jaber Preparation of Base Buffer Consider base buffer solution, containing a weak base (B) and its salt (BA) with strong acid. pH of a basic buffer = pKa + log ([base]/[salt]) PKa+ PKb=14 Dr. ahmed jaber Buffering Capacity The number of millimoles of acid or base to be added to a litre of buffer solution to change the pH by one unit is the Buffer capacity of the buffer. Β = millimoles /(ΔpH) Dr. ahmed jaber What is the pH of a solution containing 0.02 M HA and 0.01 M A-? pKa of HA = 5? Solve: pH of acid buffer = pKa + log ([salt]/[acid]) pka = 5 Acid cons. (HA)= 0.02 M Salt cons. (MA) = 0.01 M PH = 5+log (0.01/0.02 ) pH= 4.69 Dr. ahmed jaber What is the pH of a solution containing 0.10 mole of ephedrine and 0.01 mole of ephedrine hydrochloride per liter of solution? Since the pKb of ephedrine is 4.64? pH of a basic buffer = pKa + log ([base]/[salt]) pka+pkb = 14 pka=14 - 4.64 = 9.36 PH= 9.36 + log ( 0.1/0.01) PH= 10.36 Dr. ahmed jaber What is the hydronium ion concentration in a solution that containing 0.03 M HA and 0.02 M A-? pKa of HA = 4? pH of acid buffer = pKa + log ([salt]/[acid]) pH=4+ log ( 0.02/0.03) pH= 3.82 [H3O+] = 10-pH [H3O+] = 10-3.82 [H3O+] = 1.51 x 10-4 M Dr. ahmed jaber What is the hydroxide ion concentration in a solution that containing 0.20 mole of ephedrine and 0.03 mole of ephedrine hydrochloride per liter of solution? Since the pKb of ephedrine is 4.64? pH of a basic buffer = pKa + log ([base]/[salt]) pka+pkb = 14 pka=14 - 4.64 = 9.36 PH= 9.36 + log ( 0.2/0.03) PH= 10.18 pH + pOH = 14 …. pOH =14 - 10.18= 3.82 [OH-] = 10-pOH [OH-] = 10-3.82 [OH-] = 1.51 x 10-4 M Dr. ahmed jaber  Uses of Buffer Solutions 1-use of buffers in pH regulation is the use of bicarbonate and carbonic acid buffer system in order to regulate the pH of animal blood. 2-Buffer solutions are also used to maintain an optimum pH for enzyme activity in many organisms. 3-The absence of these buffers may lead to the slowing of the enzyme action, loss in enzyme properties, or even denature of the enzymes. This denaturation process can even permanently deactivate the catalytic action of the enzymes Dr. ahmed jaber THANK YOU! ?? ANY QUESTIONS PLEASE ASK Dr. ahmed jaber