Question

which change will decrease the value of k for this reaction if its standard change in enthalpy is 136 kj? select all that apply. 2 nahco3(s) na2co3(s) co2(g) h2o(g) group of answer choices removing co2 decreasing the temperature adding na2co3(s) adding h2o(g) removing nahco3(s)

Answer 1

To decrease the equilibrium constant (K) for a reaction with a positive standard enthalpy change, one could reduce the temperature or remove a product like CO2. Adding a product such as Na2CO3 would also shift the equilibrium towards the reactants, thus decreasing K.

Step-by-step explanation:

To influence the equilibrium constant (K) for a chemical reaction with a positive standard enthalpy change, one can manipulate the conditions according to Le Chatelier's principle. If the standard change in enthalpy is endothermic (positive value, in this case, 136 kJ), reducing the temperature will generally decrease the value of K because the reaction favors the exothermic direction when cooled.

Moreover, changing the concentration of reactants or products can also affect the value of K. For instance, removing CO2 (a product) would shift the reaction towards the products to re-establish the equilibrium, effectively decreasing K. Similarly, adding Na2CO3 (also a product) shifts the equilibrium towards the reactants. Conversely, adding H2O(g) increases the concentration of a product, which can actually increase the value of K, and removing NaHCO3 (a reactant) would likely increase K as the reaction would shift to replace the reactant.