Answer to Question #173988 in General Chemistry for dsf

Question

(La Chatelier lab)

You will make three changes to this equilibrium system:

• Adding solid ammonium thiocyanate (NH4SCN). NH4SCN is a soluble solid which will dissociate in water to form NH4+ ions and SCN- ions.
• Adding silver nitrate (AgNO3) which removes SCN- ions from the equilibrium system by forming an insoluble white precipitate.
• Heating and cooling the system.

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Answer:

1. Effect of adding NH4SCN: In a moment, you will be adding NH4SCN to your reaction system. Adding NH4SCN should affect the concentration of which species in the equilibrium reaction?
2. Should this speed up the forward reaction or the reverse reaction?
3. Place test tube #5 in a 250 mL beaker half-filled with water, and then heat the water to near boiling using a hot plate.
4. What do you observe happening to the solution in ice water? To the solution in hot water?

Answer 1

NH₄SCN = NH₄⁺ + SCN^{- .}

1. When we add Solid NH₄ SCN ( solid ) then no change in equilibrium system that is no shifting .

2. When we add AgNO₃ to the system the SCN remove than reaction shift forward .

3.Heating is favoured for endothermic process that shift in forwarded directions.