1. Buffers

2. Buffer Capacity A buffer solution has limited ability to react with acids and bases without changing it is pH, a solution acts as a buffer because it contains both members of conjugate acid-base pair Removal at one of these two by either chemical or physical process destroy the buffer action of the solution example: if enough strong acid is added to an acetic buffer solution all at once or little by little to react with all the acetate ion, the solution losses it is ability to act as a buffer thus continued addition of strong a cads or bases to a buffer solution losing it is ability to act as a buffer blood has a wide capacity as a buffer, that is why it's consider a best Buffer.

3. Acid-base balance in the blood The reaction of bicarbonate & carbonate salt with an acids and Bases are important for controlling: 1. The amount of CO 2 in the body 2. The acidity of the blood. Bicarbonate & Carbonate salt are derived from H 2 CO 3 as H 2 CO 3 + NaOH  NaHCO 3 + H 2 O NaHCO 3 + NaOH  Na 2 CO 3 + H 2 O excess These two reactions are the way that excess base is neutralized in the body. Carbonic acid is unstable in water as in equation H 2 CO 3  H 2 O + CO 2 H 2 CO 3 and H 2 O & CO 2 an in equilibrium in water.

4. Carbonic acid and Bicarbonate (H 2 CO 3 and HCO 3 - ) is a conjugate acid base pair act as a buffer. H 2 CO 3 + H 2 O H 3 O + + HCO 3 - A conjugate acid-Base-pair A carbonic acid H 2 CO 3 is formed by dissolving CO 2 in aqueous body fluids, it is a weak acid that ionized to HCO 3 - as in equation CO 2 + H 2 O H 2 CO 3 HCO 3 - + H + 1.2meq/l 24meq/l Normally in the body fluid such as blood, the a mount of bicarbonate is 24meq./l and the amount of carbonic acid is 1.2meq/l. HCO 3 - If the ratio of ــــــــــــــــــــ is 20 ( the pH of blood will be (7.3 – 7.4)) H 2 CO 3 HCO 3 - If the ratio of ـــــــــــــــــــــــــــــless than 20 say 16 (the pH of blood become more acidic say (7.0) ) H 2 CO 3

5. This phenomenon called acidemia & the physiological process called acidosis. HCO 3 - If the ratio of ـــــــــــــــــــــmore than 20 say 26 the (pH of blood become H 2 CO 3 more alkali more than 7.4 say 7.8), this phenomenon called alkalemia & the physiological process called Alkalosis, death some time occurs if the pH of a blood is more acidic than 6.8 or more basic than 7.8. Previously we say that all buffer solution have limited ability to with stand any addition strong acid or base with out changing their pH.(buffer capacity)

6. The buffer in the body differs from those in the laboratory. The body can replenish components of buffer solution as they are used up or can remove from the body any excess component. Consider a patient who has an illness that causes an increase in conc. Of acidic product acidosis the amount of carbonic acid increase & the amount of CO 2 formed from decomposion of H 2 CO 3 increase also this causes decrease in the ratio (HCO 3 - /H 2 CO 3 ), to loss the excess of CO 2 deeper and faster berthing called hyperventilation occur, this causes decreases in the acidity of blood because CO 2 formed is lost through the lung. If this process is not enough to return the pH of blood to the normal value, the kidney can help by releasing more carbonate ion in blood and removing hydrogen ions. In this way the body tries to return the ratio HCO 3 - /H 2 CO 3 to 20 and maintain the acid base balance in body, but if the patient have decrease in H2CO3 & in crease in concentration of basic ion, (Alkalosis) the lung and kidney work quickly to remove any excess of basic product. To prevent this state the CO 2 conserve & product more carbonic acid, loss of CO 2 through the lung is minimize by slower and shallow breathing called (hypoventilation) at this time bicarbonate ion are removed & H + is added to blood so the body return to the ratio 20 & the pH value at blood remain constant (7.3-7.4).

7. Aqueous solutions and Colloids

8. Solutions and Colloids are essential to life, the solutions in living systems are aqueous solutions that is they are made with water. Solutions:- homogenous mixture of two or more different substance the substances that make up the solution are called it's component, one of these component is more than the other's & called (solvent), the other component called solute (e.g.) sugar in water.

9. The three states of matter can combine in nine different ways to form collations containing two components these are listed in table (1). Solvent Solute ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ Liquidliquid Liquidsolid Liquidgas Solidsolid Solidliquid Solidgas Gasgas Gasliquid Gassolid Solutions that contain liquids as solutes are the types of solutions most familiar to us. Numerous examples of solutions containing solids in liquids, liquid is liquid gases in liquid are available from everyday experiences.

11. Solubility The amount of solute dissolved in a given quantity of to form saturated solution at central temperature. The solubility of a solute in certain solvent, depend on: 1. Kind of solute 2. Kind of solvent 3. Temperature Vapor pressure Solubility in crease with increasing temperature & by increasing the vapor pressure there are two type of solvent. 1. polar solvent like H 2 O & Alcohol 2. non polar solvent like benzene & ether The polar solvent like NaCl. Gasoline a mixture of no polar organic compounds is good solvent for other no polar organic compounds such as greases and oils; its follows from the general rule that polar and non polar substances will not form solutions e.g. gasoline and water.

13. Solubility Some liquids are infinitely soluble in another liquid like ethyl alcohol and water such pair of liquids is said to be(1) completely miscible. Other liquid are slightly soluble in each other, such liquids are said to be (2) partially miscible. liquids that are insoluble in each other are said to be (3) immiscible like gasoline & water.

15. The temperature of solvent affect the solubility of solute is general solutes are more soluble in hot than cold solvent the sol abilities of several solids in crease greatly with in increasing temp, other increase slightly, and some actually decrease. Gases are compound whose solubility's decrease with in creasing temp because the bubbles that from when water is heated are air escaping from solution because dissolved air is less in water at higher temp. In general the solubility of any gas increases as the partial pressure of the gas above the solution is increased.