Topic #8: Guide Questions

• Did all the experimental results agree with the

  expected or theoretical results? If not, what are the

  possible sources of errors?

  • Effect of Concentration - Yes, the results matched the expected outcomes. Adding Fe(NO3)3 and KSCN shifted the reaction forward (right), while AgNO3 and NH3 shifted it backward (left).
• Did all the experimental results agree with the

  expected or theoretical results? If not, what are the

  possible sources of errors?

  • Effect of Concentration - It agrees with the Le Chatelier’s principle
• Did all the experimental results agree with the

  expected or theoretical results? If not, what are the

  possible sources of errors?

  • Effect of Temperature - Yes, the results aligned with the theory. Warming the solution shifted the reaction backward, and cooling it shifted the reaction forward, showing the forward reaction is exothermic.
• Did all the experimental results agree with the

  expected or theoretical results? If not, what are the

  possible sources of errors?

  • Effect of Pressure - Expected: The closed tube turned yellow, trapping the CO2 and causing it to form the H2CO3. The open tube turns blue as the CO2 escapes, having less H2CO3 present.
• Did all the experimental results agree with the

  expected or theoretical results? If not, what are the

  possible sources of errors?

  • Effect of Pressure - Achieved: Both closed and open tubes turned yellow.
• Did all the experimental results agree with the

  expected or theoretical results? If not, what are the

  possible sources of errors?

  • Effect of Pressure - Likely, the added HCl interfered with the pressure effect, dominating the reaction.
• Do the results of the temperature variation

  indicate that the forward reaction is exothermic or

  endothermic? Is the reaction reversible? Explain

  your answer.

  • The temperature changes indicate that the forward reaction is exothermic.

  
• Do the results of the temperature variation

  indicate that the forward reaction is exothermic or

  endothermic? Is the reaction reversible? Explain

  your answer.

  • When the solution is cooled, it releases heat, thus, showing an exothermic reaction. The solution turns red, meaning the forward reaction or the product is favored.

  
• Do the results of the temperature variation

  indicate that the forward reaction is exothermic or

  endothermic? Is the reaction reversible? Explain

  your answer.

  • When the solution is heated, it absorbs heat, thus, showing an endothermic reaction. The solution turns pale yellow, meaning the backward reaction or the reactant is favored.

  
• Do the results of the temperature variation

  indicate that the forward reaction is exothermic or

  endothermic? Is the reaction reversible? Explain

  your answer.

  • This shows the reaction is reversible because it shifts with temperature changes.

  
• If the change in color of bromothymol blue

  indicates the presence of carbonic acid, what do

  you conclude about the effect of pressure change

  on the position of equilibrium? Write the equation

  of the reaction and briefly explain your answer.

  • CO2(g)+H2O(l)↔H2CO3(aq) - When pressure increases (in the closed test tube), more CO2 is trapped, which shifts the equilibrium towards forming more H2CO3 or to the right, causing the solution to turn yellow.
• If the change in color of bromothymol blue

  indicates the presence of carbonic acid, what do

  you conclude about the effect of pressure change

  on the position of equilibrium? Write the equation

  of the reaction and briefly explain your answer.

  • CO2(g)+H2O(l)↔H2CO3(aq) - Higher pressure favors the product or H2CO3 formation.
• If the change in color of bromothymol blue

  indicates the presence of carbonic acid, what do

  you conclude about the effect of pressure change

  on the position of equilibrium? Write the equation

  of the reaction and briefly explain your answer.

  • CO2(g)+H2O(l)↔H2CO3(aq) - When the pressure decreases (in the open test tube), CO2 escapes, which shifts the equilibrium away from the H2CO3 formation or to the left, turning the solution blue.
• If the change in color of bromothymol blue

  indicates the presence of carbonic acid, what do

  you conclude about the effect of pressure change

  on the position of equilibrium? Write the equation

  of the reaction and briefly explain your answer.

  • CO2(g)+H2O(l)↔H2CO3(aq) - Lower pressure favors reactants or reduces the H2CO3 formation.