Answer to Question #60125 in Physical Chemistry for joseph orobiyi

Question

16 Equilibrium is a state of dynamic molecular behaviour, meaning that
the reaction eventually comes to a stop.
products continually turn into reactants at a progressively faster rate.
reactants turn into products and products turn into reactants at
different rates.
reactants turn into products and products turn into reactants at equal
rates



17 The reaction below is exothermic: $2SO_2 (g) + O_2 (g) \rightarrow
2SO_3 (g)$. Le Chatelier's Principle predicts that __________ will
result in an increase in the number of moles of $SO_3$ (g) in the
reaction container.
removing some oxygen
decreasing the pressure
increasing the pressure
increasing the volume of the container

Answer 1

16. Equilibrium is a state of dynamic molecular behavior, meaning that reactants turn into products and products turn into reactants at equal rates.

Explanation: when the reaction occurs, the rates of forth and back reactions are different. For normal reaction, the rate of forth reaction is much bigger than that of the back one. Then, with time the rate of forth reaction decreases and at equilibrium the rates of forth and back reactions are equal. So, at the equilibrium, the reaction doesn’t stop at all. You still have some reactants and some products, and the reaction is going both ways. But as the rates are equal, the effective composition of the system doesn’t change. This equilibrium is stable: small changes in the conditions result in small changes in the system.


17. The reaction below is exothermic: 2SO2(g) + O2(g) 2SO3 (g). Le Chatelier's Principle predicts that increasing the pressure will result in an increase in the number of moles of SO3(g) in the reaction container.

Explanation: Le Chatelier’s principle tells that the system is always trying to compensate the actions of the surroundings. For example, if you have exothermic reaction (when the heat is released when the products turn into reactants), the increase of temperature with move the equilibrium towards the products (i.e. consuming energy and decrease the temperature). The same situation with pressure. The increase of pressure in the reaction above will increase the concentration of product, i.e. sulfur (VI) oxide. This is because the pressure of gas decreases when 3 moles of gas turn to 2 moles of gas, so increasing of the forth reaction extent will compensate the increase of pressure.