Chapter 19, Problem 5STP

Interpretation Introduction

Interpretation: In the given equilibrium reaction, the correct factor causing equilibrium to shift to the right are to be chosen.

Concept introduction:

The concept involves the study of Le-Chatlier’s principle. This principle studies the shift of equilibrium by a change in temperature, pressure and volume of the equilibrium mixture.

According to it, by changing temperature, pressure or volume equilibrium shifts towards the direction which compensates the effect of change.

Answer to Problem 5STP

C

Explanation of Solution

The given equilibrium reaction is:

$2\text{S}(\text{s})+5{\text{F}}_2(\text{g})\rightleftarrows \text{S}{\text{F}}_4(\text{g})+\text{S}{\text{F}}_6(\text{g})$

• On increasing the concentration of $\text{S}{\text{F}}_4$, equilibrium will shift to the left to undo the effect.
• On increasing the concentration of $\text{S}{\text{F}}_6$, equilibrium will shift to the left to undo the effect.
• On increasing the pressure of the system, equilibrium will shift to the right because there is less number of gaseous moles on the right side. The shift in equilibrium will compensate the effect of an increase in pressure.
• On decreasing the pressure of the system, equilibrium will shift to the right because there is less number of gaseous moles on the right side. The shift in equilibrium will compensate the effect of an increase in pressure. Thus, option C is correct.

Conclusion

• On increasing the concentration of $\text{S}{\text{F}}_4$ , equilibrium will shift to the left to undo the effect. Thus, option A is incorrect.
• On increasing the concentration of $\text{S}{\text{F}}_6$, equilibrium will shift to the left to undo the effect. Thus, option B is incorrect.
• On decreasing the pressure of the system, equilibrium will shift to the left because on the left side there are more gaseous moles. The shift in equilibrium will compensate the decrease in pressure. Thus, option C is incorrect.