How can you increase the concentration of the product (s) in each of these reactions by varying the temperature and pressure (caused by volume change)?
4NH3 + 5O2 <=> 4NO + H2O
Delta H = -903.75 kJ
Br2 + Cl <=> 2BrCl
Delta H = 14.64 kJ
Please help...
With gaseous reactions, increased pressure causes the reaction to shift to the side that occupies the smaller volume. With increased temperature, the reaction shifts to use the heat that has been added. For the heat part of the problem, it often helps to write exothermic reactions this way.
4NH3 + 5O2 ==> 4NO + H2O + heat
and endothermic reactions this way.
Br2 + Cl + heat <==>2BrCl
With this in mind post your thoughts and we shall be happy to critique the work. Tell us why you have made the decision you made.
To increase the concentration of the product(s) in each reaction, you can vary the temperature and pressure (caused by volume change). Let's analyze each reaction separately:
1. 4NH3 + 5O2 <=> 4NO + H2O (ΔH = -903.75 kJ)
In this exothermic reaction, increasing the temperature will shift the reaction towards the reactant side (NH3 and O2) to use the added heat. So, to increase the concentration of the product (NO and H2O), you would decrease the temperature.
Regarding the pressure, increasing the pressure will shift the reaction towards the side that occupies the smaller volume. By using the ideal gas law, PV = nRT, we can see that reducing the volume will increase the pressure. Since there are fewer moles of gas on the product side (NO and H2O), decreasing the volume will favor the formation of more product. Therefore, to increase the concentration of the product, you would decrease the volume or increase the pressure.
2. Br2 + Cl <=> 2BrCl (ΔH = 14.64 kJ)
In this endothermic reaction, increasing the temperature will favor the product side (BrCl) to absorb the added heat. So, to increase the concentration of the product, you would increase the temperature.
Regarding the pressure, as mentioned before, increasing the pressure will shift the reaction towards the side that occupies the smaller volume. However, in this case, both the reactant side (Br2 and Cl) and the product side (BrCl) have the same total number of moles of gas (2 moles). Therefore, changing the pressure/volume will not affect the equilibrium concentration of the products.
To summarize:
- For the reaction 4NH3 + 5O2 <=> 4NO + H2O, you would decrease the temperature and decrease the volume or increase the pressure to increase the concentration of the product.
- For the reaction Br2 + Cl <=> 2BrCl, you would increase the temperature to increase the concentration of the product. The pressure/volume change will not affect the equilibrium concentration of the products in this particular reaction.