Q. 10.24 - An Introduction to General, Organic, and Biological Chemistry

Question

Use Le Châtelier's principle to predict whether each of the following changes causes the system to shift in the direction of products or reactants:

$HN{O}_2\left(aq\right)+H_{2}O\left(l\right)\rightleftarrows N{O}_2^{-}\left(aq\right)+H_3{O}^{+}\left(aq\right)$

a. adding more $HN{O}_2\left(aq\right)$

b. removing some $N{O}_2^{-}\left(aq\right)$

c. adding more $H_3{O}^{+}\left(aq\right)$

d. removing some $HN{O}_2\left(aq\right)$ 

Step-by-Step Solution

Answer

(Part a)  The system shifts in the direction of products. 

(Part b)  The system shifts in the direction of products. 

(Part c)  The system shifts in the direction of reactants. 

(Part d)  The system shifts in the direction of reactants. 

Step 1: Introduction (Part a)

The given is the chemical equation 

$HN{O}_2\left(aq\right)+H_{2}O\left(l\right)\rightleftarrows N{O}_2^{-}\left(aq\right)+H_3{O}^{+}\left(aq\right)$

To find whether each of the following changes causes the system to shift in the direction of products or reactants using Le Châtelier's principle 

Step 2: Explanation of (a)

One of the reactants is${\mathrm{HNO}}_2$ . When some ${\mathrm{HNO}}_2$ is added, the equilibrium shifts to that direction where it is consumed. So the system shifts in the direction of products.

Step 3: Explanation of (b)

One of the reactants is ${\mathrm{NO}}_2^{-}$ . When some ${\mathrm{NO}}_2^{-}$ are removed, the equilibrium shifts to that direction where more products are formed. So the system shifts in the direction of products.

Step 4: Explanation of (c)

One of the reactants is ${\mathrm{H}}_3{\mathrm{O}}^{+}$. When some ${\mathrm{H}}_3{\mathrm{O}}^{+}$  are added, the equilibrium shifts to that direction Where products are consumed. So the system shifts in the direction of reactants.

Step 5: Explanation of (d)

One of the reactants is ${\mathrm{HNO}}_2$. When some ${\mathrm{HNO}}_2$ is removed, the equilibrium shifts to that direction where reactants are produced. So the system shifts in the direction of reactants.