7.1.1

I can outline the characteristics of chemical and physical systems in a state of equilibrium.

Equilibrium- a reaction in which the rate of the forward reaction is equal to the rate of the backward reaction. The concentrations of reactants and products are constant as well.

Examples of dynamic equilibrium



This is an example of an dynamic equilibrium in the physical system.
Bromine is a volatile liquid so many particles have enough energy to escape from the liquid state to form vapour. But at the same time, some of the vapour molecules collide with the surface of the liquid thus lose liquid and become a liquid. There is no net change between the amounts of gas and liquid.



This is an example of a chemical system. The reaction of dissociation between hydrogen iodide and its elements hydrogen and iodine. At the start of the reaction, there is an increase in purple due to the production of iodine gas but after the while there is no more change. At the stage, it could be said that equilibrium has been reached since there is no net change between the concentrations of the products and reactants.

We were observing a dynamic equibrilium occuring in copper sulphate. Hydrated copper sulphate appears as blue whilst anhydrous copper sulphate turns white. This could be used as a test for water, but not for pure water just for any substance that contains water. When hydrated copper sulphate is heated, it turns white and when water is added back in again it turns blue.