Question

General Chemistry II Laboratory Manual, 2017 Revision Questions: 1) Using the equilibrium shown below, fill in the table showing which way each stress would shift things to reestablish equilibrium and the effect on the value of Kc cach stress will have. Assume that only the stress that is being applied is happening to the system at equilibrium and nothing else changes (e. the volume of the container remains constant unless you are told otherwise). 2CHCl(g) +Cl2(g) = 2CCL.(1) + H2(g) AH = -60 kJ Stress Direction of shift to re- Change in the value of establish equilibrium Ko Add Clave Add CC40 Remove CHC13() Cool System Add a catalyst Reduce volume Add Hee 2) For the equilibrium shown below, list three things that you could do to increase the yield of the products. H2O(g) + C(s) = CO(g) + H2(g) AH = 130 kJ

please help

Answer 1

Question 1)

Part a) Adding Cl₂

According to Le Chatelier's Principle, adding Cl₂ will mean that the reaction will proceed in a way such that concentration of Cl₂ is decreased. This will happen when the shift is towards the product i.e. rightwards. Changing the concentration of species doesn't change K_C

Part b) Adding CCl₄

CCl₄(l) is a pure liquid phase component. Reaction equilibrium is unaffected by adding a pure liquid phase component. Thus no change in reaction as well as K_C doesn't change.

Part c) Remove CHCl₃

According to Le Chatelier's Principle, removing CHCl₃ will mean that the reaction will proceed in a way such that concentration of CHCl₃ is increased. This will happen when the shift is towards the reactants i.e. leftwards. Again, changing the concentration of species doesn't change K_C

Part d) Cool the system

The reaction is exothermic because Thus, there is a heating effect present. According to Le Chatelier's Principle, cooling the system will shift the equilibrium towards products side i.e. rightwards for an exothermic reaction. This is the case where K_C will change because K_C depends only on temperature. For an exothermic reaction, cooling will cause, a increase in K_C

Η <0

Part e) Adding a catalyst

Adding a catalyst neither changes the equilibrium, nor it changes the value of K_C. It only speeds up the time taken to reach equilibrium.

Part f) Reducing the volume.

This is equivalent of increasing the pressure. According to Le Chatelier's Principle, increasing pressure will shift the reaction towards the side which has fewer moles of gas. Here, reactants have 3 mole of gas (Cl₂ and 2CHCl₃) whereas the product side has 1 moles (H₂). Thus, reaction will shift rightwards. Changing pressure has no effect on K_C

Part g) Add He

He(g) is an inert gas. Adding inert gas at constant volume doesn't shift the equation because inert gas affects both the reactant sides and the product sides equally. It also doesn't change K_C

Final answer

Stress	Shift	Effect on KC
Add Cl2(g)	Rightwards	No Change
Add CCl4(l)	No Change	No Change
Remove CHCl3(g)	Leftwards	No Change
Cool the system	Rightwards	Increase
Add Catalyst	No Change	No Change
Reduce Volume	Rightwards	No Change
Add He(g)	No Change	No Change

Question 2

To increase the yield of product, one can

a) Increase the temperature- For an endothermic reaction, increasing temperature will increase the product yield.

b) Reduce pressure by expanding- This will shift the equilibrium to right because right side has more number of gaseous moles.

c) Keep removing the Products CO and H₂. This will again shift the equilibrium towards products.