Answer to Question #286493 in General Chemistry for Dube

Question

a 50 ml sample of .1 mol/L HCIO(aq) is titrated with .2 mol/L KOH(aq). find ph given the following volumes of added base: (Ka= 2.8 x 10-8) a) 0.0 ml b) 10.0 ml c) 25.0 ml d) 30.0 ml. show your work

Answer 1

CH$_3$ COOH $+$ NaOH $\to$ CH$_3$ COONa$+H_2O$

Number of moles of CH$_3$ COOH

$=0.150×\frac{50}{1000}=0.0075\>moles$

Number of moles of NaOH

$=0.150×\frac{20}{1000}$

$0.003\>moles$

Moles of excess acid$=0.0075-0.003$

$=0.0045\>moles$

PH$=$ $pk_a+$ log $\frac{[A^-]}{[HA]}$

$=-log\>1.8×10^{-5}+log\>\frac{0.003}{0.0045}$

$=4.7447-0.1761$

$=4.586$