Acid-base titration
Tutorial 9
pH during titration of a strong acid by a strong base
Schematic:
Determination of the base volume $ V_e $ added at the equivalent point
$n_{added\;base}$ $= $ $n_{initial\;acid}$
$V_e\cdot c_{base}$ $=$ $V_i\cdot c_{acid}$
so $V_e$ is calculated.
Calculation of pH ($v$ = volume of added base)
$v=0$
pH of a strong acid with molarity $c_{acid}$:
$pH=-log\;c_{acid}$
$v\lt V_e$
Determine the number of moles of acid $ n_a $ that have not yet reacted, then:
$pH$ $=$ $-log\frac{n_a}{V_i+v}$
$v=V_e$
$pH=7$
$v\gt V_e$
Determine the numbers of base moles $ n_b $ in excess, then:
$pH$ $=$ $14+log\frac{n_b}{V_i+v} $
$ 20 \; mL \; HCl \; 0.10 \; M $ are titrated by $ NaOH \; 0.1 \; M $. Calculate the pH at the beginning of the titration.
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Complete please this question before moving on to the next one!
Strong acid:
$pH$ $=$ $-log\;c_{acid}$
$pH$ $=$ $-log\;0.10$ $=$ $1.0$
