Chemistry and Chemical Reactivity (9th Edition)

$pH=2.57$
Initial molarity: $94.5/1000\ g\div 94.50\ g/mol\div 125/1000\ L=0.008\ M$ $K_a=x\cdot x/(0.008-x)$ $x=[H_3O^+]=0.0027\ M$ $pH=2.57$