Question

Consider the equilibrium below:

A + B C + D + E

Ho < 0

Use LeChatelier's principle to predict the effect on the concentration of the equilibrium concentration of E caused by each of the following actions:

action	result on [E]
adding C	---Select--- increases remains unchanged decreases
removing D	---Select--- increases remains unchanged decreases
increasing the temperature	---Select--- increases remains unchanged decreases

Answer 1

adding C -- On increasing the concentration of C , reaction moves in such a way so as to decrease the concentration of C. Reaction moves in backward direction. Equilibrium shifts towards left. Concentration of E decreases.

According to Le Chatelier's principle if a system at equilibrium is subjected to a stress then the system behaves in such a way so as to reduce the stress. Effect of temperature : When temperature is increased then reaction shifts in that direction which absorbs heat and reduces temperature. In an exothermic reaction when temperature is increased then reaction shifts towards left direction and vice versa. In an endothermic reaction when temperature is increased then reaction shifts in right direction. Effect of pressure : When pressure increases volume decreases hence no. Of moles increases and reaction shifts in such a direction so as to reduce the number of moles i.e reaction shifts towards that side which have lesser no. of moles. Concentration : When concentration of product increases then reaction shifts towards product side and vice versa. When concentration of reactants increases then reaction shifts towards product side and vice versa. Catalyst : No effect on equilibrium.

Removing D -- on decreasing the concentration of D , reaction moves in such a way so as to increase the concentration of D. Reaction moves in the forward direction. Equilibrium shifts towards right. Concentration of E increases.

Increasing the temperature -- This reaction is exothermic i.e. heat is released during the reaction. On increasing the temperature , reaction moves in such a way so as to decrease the temperature. Reaction moves in backward direction. Concentration of E decreases.