Question 1: Stoichiometry and Concentration
You work as a senior scientist and while inspecting the lab one day you see a bottle
simply labeled \"Na$_2$SO$_4$ Solution\". You ask the associate researcher working at that
bench to find out the concentration of this solution, and she mixes 250.0 mL of it with
250.0 mL of a 0.500 M BaCl$_2$ solution. After she did the mixing, a precipitate formed.
She then performed a filtration and collected 12.5 grams of a pure solid. Assuming
that the precipitation reaction yield was 100.0%, what was the concentration (in
molar) of the unknown Na$_2$SO$_4$ solution?
Question 2: Ionic Strength and Activity Coefficients
a) Calculate the concentration of [Hg$_2^{2+}$] in equilibrium with 0.010 M KCl saturated
with Hg$_2$Cl$_2$.
b) Find the concentration of hydronium ions and the pH of 0.05 M LiNO$_3$. Assume the
temperature is 25 degrees C. Hint: you may need the activity coefficients of H$^+$ and
OH$^-$ which are listed in Table 8-1 in your textbook.