Question

how many grams of weak acid HF(molar mass=20.01g/mole) does it take to prepare 715mL of a solution that has PH=2.
075

Answer 1

$[H3O^+] = 10^{(-pH)}$

$[H3O^+] = 10^{-2}=0.01M$

$Moles =Molarity ×volume$

$Moles =0.01×\frac{715}{1000}=0.00715moles$

$Mass=0.00715×20.01=0.14grams$