Final answer:
When OH- is added to a chemical reaction at equilibrium, the equilibrium shifts according to Le Chatelier's Principle, typically resulting in a shift toward the products to counterbalance the addition of OH-.
Step-by-step explanation:
In Test Tube 1, when OH- is added to a reaction at equilibrium, the reaction will shift according to Le Chatelier's Principle, which states that the system will adjust to minimize the disturbance. If we use the given example of the reaction N2 + 3H2 → 2NH3, the addition of OH- would shift the reaction in the opposite direction of the H+ ions, as H+ and OH- would combine to form water (H2O). Given that the provided demonstration pertains to a different reaction involving Cr2O72- and OH-, adding OH- would similarly shift the equilibrium away from H+ ions, resulting in the formation of more products such as CrO42- (in the case of the chromium reaction). Therefore, in the context of a balanced reaction in a basic solution, the addition of OH- will generally cause the equilibrium to shift toward the products.