In: Chemistry
A buffer solution is prepared from equal volumes of 0.200 M acetic acid and 0.600 M sodium acetate use 1.80 *10^-5 as Ka for acetic acid.
a.) what is the pH of the solution
b.) Is the solution acidic or basic
c.) What is the pH of a solution that results when 3.00ml of 0.034 M HCl is added to 0.200L of the original buffer
PKa = -logKa
= -log(1.8*10^-5)
= 4.75
PH = PKa + log[CH3COONa]/[CH3COOH]
= 4.75 + log0.6/0.2
= 4.75 + 0.477
= 5.227
b. PH = 5.227
The solution is acidic
c.
no of moles of CH3COONa = molarity *volume in L
= 0.6*0.2 = 0.12moles
no of moles of CH3COOH = molarity *volume in L
= 0.2*0.2 = 0.04moles
no of moles of HCl = molarity * volume in L
= 0.034*0.003 = 0.000102moles
no of moles of CH2COONa after addition o f0.000102moles of HCl = 0.12-0.000102 = 0.119898moles
no of moles of CH2COOH after addition o f 0.000102moles of HCl = 0.04+0.000102 = 0.040102moles
PH = PKa + log[CH3COONa]/[CH3COOH]
= 4.75 + log0.119898/0.040102
= 4.75 + 0.4756
= 5.2256 >>>>answer