What does dynamic equilibrium mean in terms of macroscopic and microscopic changes?
Dynamic equilibrium can be pictured out as the forward reaction rate is equal with the reverse reaction rate. For example, a certain reaction is done between a gas A and gas B to produce gas C. We can write the equation as:
A + B -> C
where gas C is accumulated. At some point, when the closed container is full of gas C, gas C will decompose to produce gas A and gas B back. The reaction will be:
C -> A + B
Finally, the rate of of A + B -> C is equal to the rate of C -> A + B.
Microscopically, we are looking in the formation of moles. There is an equal number of moles that is produced in both sides. If for example the production of moles of forward reaction is greater, the equilibrium is disturbed.
Macroscopically, we are looking at the physical manifestation of the reaction. An example would be the decomposition of Calcium carbonate to Calcium Oxide and Carbon dioxide.
CaCO3 (solid) <---> CaO (solid) + CO3 (gas)
The production of CO2 will exert pressure in the container thus raising the pressure gauge. After sometime, the pressure gauge will go down because of the reverse reaction until it is nailed in a specific pressure reading. At that constant pressure, equilibrium exists.