Question

1/Calculate the volume of NaOH conc = 0,12 mol/dm3 needed to neutralize 10 cm3 HCl conc 0,20 mol/dm3.

2/ Calculate how much NaOH conc 0,10 mol/dm3 will be used in titration of 12 cm3 H3PO4 conc 0,20 mol/dm3 with use of a) methyl orange b) phenolphtalein.

3/ KMnO4 is stadardised with H2C2O4. For it 28,8cm3 of KMnO3 is used and 0,276g H2C2O4x 2H2O. What is the concentration of KMnO4?

Answer 1

NaOH (aq) + HCl (aq) → NaCl (aq) + H₂O

Moles of HCl$=0.20×0.01=0.002moles$

Volume of NaOH$=\frac{0.002}{0.12}=0.016litres$

3NaOH(aq) + H₃PO₄(aq) → Na₃PO₄(aq) + 3H₂O(l)

Moles H3PO4$=0.012×0.20=0.0024moles$

Miles NaOH$=3×0.0024=0.0072moles$

Voleme NaOH=$\frac{0.0072}{0.10}=0.072litres$