9.9 4:25 13Read Only - You can't save changes to this..Le Chatelier's principle (Sec. 9.9) considers the effects of outside forces on systems atchemical equilibrium. According to this principle, a stress applied to the system can favorthe chemical reaction that will reduce the stress – either the forward reaction, in which casemore product is formed, or the reverse reaction, in which case more reactants form. Some ofthe stresses that can cause this readjustment of the chemical equilibrium are concentrationchanges, temperature changes, and pressure changes.9.9a. Indicate whether each change in conditions below would shift the chemical equilibrium ofthe following chemical reaction to the left or to the right:СH4(g) +20-(3)CO2(g) + 2H20(g) + heatEquilibriumChangeChange in conditionsExplanationincreasing theconcentration of 02increasing the temperatureof the reactionintroduction of aneffective catalyst for thisreactionincreasing the pressureexerted on the reactionb. Indicate whether each change in conditions below would shift the equilibrium of thefollowing chemical reaction to the left or to the right:N2(g) + 202(g) + heat =EquilibriumChangeChange in conditionsExplanationincreasing the concentrationof 02increasing the temperatureof the reactionintroduction of an effectivecatalyst for this reactionincreasing the pressureexerted on the reactionCengggopublicly02016Learning. Ail Rights Reserved. May not be scanned, copied or duplicated, or posted to aaccessible website, whole or in part.76Chapter 9Chemical Reactions75Self-restTrue-false: Indicate whether the following statements are true or false. If the statement isfalse, give the word or phrase that may be substituted for the underlined portion to makethe statement true.1. The reaction 2CUO * 2Cu + 02 is an example of a displacement reaction.2. The oxidation number of a metal in its elemental state is always positive.3. The oxidation number of oxygen in most compounds is-2.4. A substance that is oxidized loses electrons.5. A reducing agent gains electrons.6. Adding heat to an endothermic reaction helps the reaction to go toward the productsside.7. The addition of a catalyst will not change the equilibrium position of a chemical reaction.8. The rate of a reaction is not affected by the addition of a catalyst.9. Increasing the concentration of products in a chemical equilibrium reaction shifts theequilibrium toward the product side of the reaction.10. In a chemical equilibrium constant expression, the concentrations of the reactants arefound in the numerator.I1. A large chemical equilibrium constant indicates that the equilibrium position is to theright side.of the equation.12. In chemical equilibrium constant expressions, concentrations of pure solids and pureliquids remain constant.

Given, Change in conditions Equilibrium change Explanation Increase in concentration of O2 Shift towards right side According to Lechatelier's principle, change in equilibrium (an increase in the concentration of oxygen ) will be restored to equilibrium state by shifting the equilibrium towards the product side. Increase in temperature of the reaction Shift towards left side Here heat acts as products. Therefore, an increase in temperature shift the equilibrium to reactants side to reestablish equilibrium. Introduction of an effective catalyst No change Addition of catalyst has no effect in the position of equilibrium as it increases the speed of reaction backward and forward equally. Increase in pressure No change The number of moles of reactants and products are same.Given, 2N2 (g) + O2 (g) + heat ↔ 2N2O Change in conditions Equilibrium change Explanation Increase in concentration of O2 Shift towards right side According to Lechatelier's principle, change in equilibrium (an increase in the concentration of oxygen ) will be restored to the equilibrium state by shifting the equilibrium towards the product side. Increase in temperature of the reaction Shift towards right side Here heat acts as reactants. Therefore, an increase in temperature shift the equilibrium to products side to reestablish equilibrium. Introduction of an effective catalyst No change Addition of catalyst has no effect in the position of equilibrium as it increases the speed of reaction backward and forward equally. Increase in pressure Shift towards right side Chemical equilibrium shift towards side where the number of moles is less. Therefore, chemical equilibrium shifts towards right side.