Question

is a solution that resists changes in pH when a small amount of acid or base is added to best buffer solutions are prepared from weak acids and their conjugate base added as a sodium of potassium salt. Most biological systems must maintain a very narrow range of pH; therefore, buffers allow the biological solution to function correctly. Blood is a good example of a biological system that must maintain a pH in a very narrow range from 7.3 to 7.4 in order to carry oxygen to the cells. A small change in pH of as little as 10% is enough to destroy the bloods capacity to hold oxygen. The buffering system within the blood is based upon the solubility of Co, in water that forms carbonic acid, H,CO3. The carbonic acid conjugate base is HCO, Since buffers are generally made from acid and their conjugate base or bases and their conjugate acids, the application and understanding of acid base equilibrium is essential to determining the function and ability of the buffer system; therefore, the buffer can be understood through the same mathematical approach. A weak acid will react with water to produce its conjugate base, while the conjugate base will interact with water to produce the acid: HA (acid) +H,0 -1,0 + A (conjugate base) A (base) + H20 - OH+HA (conjugate acid) 1. What are the sodium salts of the following acids? What are the K values for these acids? There may be more than one salt for the acid and more than one K, value for the acid. a. HNO b. HF c. H,PO 2. What are the chloride salts for the following bases? a. NH, b. CHÁNH, The above acid and base reactions are represented by their equilibrium expression, K, and K When the salt containing the conjugate are present in solution, the buffer solution can react in one of two ways. The acid can be used to neutralize base added to the solution and the reaction will shift to replace the acid that is removed. When small amounts of acid are added to the buffer solution, the conjugate base or the salt of the conjugate base is used to neutralize the acid and the reaction shifts to replace the base that is removed. The ability of the buffer to react with the acid or base added is dependant upon the concentration of the weak acid and conjugate base which is called the buffer

Answer 1

= HNO is a weak acid and react with water as below - HNO₃ + H2O 430 + + No Here conjugate base of the acid is NO this Thus the sodium salt of acid is - Na NO2 The ka value of the acid is- ka = [H3o+] [NO27] - = 4.5 x 10-4 [HNO2] b. Similarly - HF + H2O Ť Hoot + F- Conjuga te base - F- Thas the sodium salt of this acid is - NaF The ka value of the acid HF can be given as -

ka – [H3O+] [F [HE] ] = 3.5x10 4 H3PO4 contain 3 acidic H atom. H₂PO4 F H + + H₂PO4 H2 Poa ² H+ +H POG2- HPO ² H t + PO 3 - Thus, the sodium salts are - Na H₂PO4 , Na2HPO4 , Na, Poa Ka - [H3O+] [ Hq pog] [H3 Poq 7 = 7.1 x 10-3 = 6-3 x 10-8 Ka - [4 30+] [HP Op 2-] . TH2PO4 ] [#30t] [ PO 4 3 - [ HP og 2- ] = 4.5 x 10-13 a Ntg + H2O Conjugate acid NHAT + Et NHgt

Thus the Base is chloride salt of NHAU the b CHg NH2 + H2O - CH₂ NHg tot Conjugate acid Hp Witz So the chloride salf of the given base is - CH3NH2 d)