Question

A buffer solution was prepared by adding 4.72 g of sodium acetate, NaCH, CO2, to 2.50 10 mL of 0.100 M acetic acid, CH3CO,H (K, = 1.8 x 10-6). a What is the pH of the buffer? pH = 5.10 Correct Find the pH using the Henderson-Hasselbalch equation: 4.72 g 1 mol NaCH, CO2 CH,CO2- ] = [NaCH,CO2] = 0.250 L -= 0.230 M 82.03 g [CH, CO2- pH = pK,+ logo = -log(1.8 x 10-5) + log CH, CO2H] 10.230 0.100 b What is the pH of the system if you add 84 mg of NaOH to the 1.00 10 mL of the prepared buffer solution? pH =

Answer 1

the given: Mass of Nach, CO2 = 4.729 Molas mans g Nacug 02= 82.03 43 g/mol Moles of Nach, coz= mass of Na cu 302 Molar mass og Na cugrož 4.729 82.03439/mol -0.0575 369083 mol rolume of so Culton = 2.50 x10mL = 2.50x18x10²L Molarity of Nach, CO2 = Molaelty of cuzz = Moles of Nach2O2 Volume of solution = 0.05.75369083mol 2.50 x10²x10²L = 0.230 147 633 M

gruen: Ka (Cuzcoon) = 1.8x105 Pka = -log Cia) = -log. (18x105) 4.74472749 [cuzcoon] = 0.100M we know that Henderson- Hassel balch equation pe plat log [conjugate herse] [weak ald) = pkat log (CM3C00] fi [cuz coon) = 4.74472749 + log (0.230147633) = 4.741121" O TO.100) 50 = 5.106734 = 5:11_ ① given: Mass of Naoh = 84mg = 84 x10 g Molare mass g Naona 39.997 g/mol Moles g Naoks 84xiog 39.997 g/mol = 0.00210015751mol

givene rolume of solution - 1:00x10mL = 1.00x18-xión Moles g cug cool= Molasity g cuzcool x volume of solution - Biloomal x 1.00 xlőxioly = 0.01 mol Constructing ICE table for the reaction: CH₃ COOH (aa) + on caa) ² cuzcoo (aq) +82016) Inpipal 0.01 0.00210015751 0.0575369083 (moles) Change -0.00210015 751 -0.00210015751 +0-0021001575 0.0596370658 Equilbaum 0.00 789984249 0 Strice rolume is same, we can assume that: [cugeoo] * Moles g cuzcoo and [cuccoon ~ Moles g cua coon in Henderson- Hasselbalch equation from egn. (1) PH= 4.74472749 + log 0.0596370 658 0.00789984 249 = 5. 622 62533 - 5.62