A. Which way should the equilibrium shift when Na2SO4 is added? How do your results support your answer?
It should shift to the left because adding any component causes the equilibrium to shift to the opposite side.
B. Which way should the equilibrium shift when NAHSO4 is added? How do your results support your answer?
It should shift to the right because the removal of a component causes the equilibrium to shift to the side from which the component was removed.
C. Is this reaction endothermic or exothermic? How do you know?