Gas Equilibriums: Examples of Reversible Reactions

1662 Words4 Pages

Gas Equilibriums: examples of Reversible Reactions

Q1. Identify the general chemical and physical characteristics of gas equilibriums as a group. Explain the forward and reverse reaction mechanisms. Use nitrogen dioxide and hydrogen iodide as examples and explain how equilibrium is reached.

The general chemical characteristic of gas equilibriums is when the concentrations of reactants and products do not change with time. This is known as the state of reversible reaction. At this state, pressure, density, colour and concentration can be recognised. At equilibrium, both the forward and backward reactions are still continuing because the rates of the forward and backward reactions are equal. This leads to the general physical characteristic of gas equilibriums which is the concentration of each substances become constant and the system is said to be at dynamic equilibrium. The equilibrium can be established in physical equilibrium and in chemical equilibrium.

A reversible reaction that takes place in both the forward and backward directions can be demonstrated by the reaction between gaseous hydrogen and iodine vapours to give gaseous hydrogen iodide:

The physical characteristic for this reaction is that the colour changes from purple to colourless.

Another example would be the reaction gaseous dinitrogen tetroxide vapours to give gaseous nitrogen dioxide is a reversible reaction and may be expressed as:

N2O4 (g) 2NO2 (g)

At equilibrium, the rate of decomposition of N2O4 is equal to the rate of combination of NO2. As the NO2 increases, then it starts declining as NO2 starts combining to form N2O4. This is called reverse reaction. The physical characteristic for this reaction is that the colour changes from colourless, d...

... middle of paper ...

...this system is increased or decreased, then the time taken to reach equilibrium will not be effected after it was in equilibrium stage.

3. When the volume changes were made and the reaction restarted, the reaction rates were affected. This is because in a low pressure system, the rate of the reaction would be slower because of the space between the particles being bigger and as a result of this, time between collisions (necessary for reactions) also increases.

4. The reason why the position of the equilibrium was unaffected in this reaction because of reaction:

1 mole + 1 mole 2 moles

If the volume is changed, then it will have an equal effect on the concentration of reactants and of products. This is because there are an equal number of moles of gaseous substances on both sides of the arrow. Therefore, the position of the equilibrium was unaffected.

Open Document