Topic 7.1.1

Equalibrium

Equalibrium is when the forward and backward reaction is the equal and same. The rate of the forward and backward reaction is the same and equal. Equalibrium is reached when the concentration of the product and reactant become constant (not necessary equal)

Systems that are in dynamic equilibrium

1.)    Physical systems

Bromine in a sealed container at room temperature. Bromine is a valotile liquid with a boiling point close to room temperature. Therefore, there will be some liquid bromine particles evaporating into gas bromine particles. However, the gas bromine particles will collide with the liquid bromine particles and loses its energy and turn back into liquid bromine particles. At one point, the rate of evaporating will be equal to the rate of condensation therefore there will be no net change in amount of liquid and gas present. This is when equalibrium is reaches. It is dynamic because it keeps occurring the whole time and the reaction doesn’t stop.

2.)    Chemical systems

Disassociating HI from H₂/I₂(2HI(g)←→H₂(g)+I₂(g)). Iodine is release as purple gas while hydrogen and hydrogen iodide are colorless. If we put hydrogen iodide into a seal container, there will be an increase in the purple owing (iodine gas). However, after a period of time, this will stop. The reaction has reached its equalibrium and the rate of disassociating hydrogen iodine is equal to the rate of associating hydrogen and iodine. The concentration of hydrogen iodide and the concentration of hydrogen and iodine is constant. This is a nonstop process so it’s at its dynamic equalibrium. 

Copper sulfate

Hydrated copper sulfate is at its dynamic equalibrium. The rate of the water going into the crystal is equal the rate of water leaving the crystal. This is why copper sulfate doesn’t change its color. However, if we heat it, we can increase the rate of reaction can cause the water leaving the crystal to increase. This make the cystal turn white. We can reverse this by dropping water on the crystal and make it turn back to blue. But when copper sulfate is at its normal state, there is a dynamic equilibrium between water going into the crystal and water leaving the crystal. The rate of water going in and water leaving the crystal is the same so therefore the crystal doesn’t change color. The crystal will be blue if its hydrated copper sulfate and white if its anhydrous copper sulfate.

Image of hydrated copper sulfate before heating, after heating and after adding back water.