1Why is it possible to add up different balanced chemical eq

1.Why is it possible to add up different balanced chemical equations to form a particular chemical equation and calculate its Kc from multiplying the Kc values of the different equations?

2. Write the 5 steps to calculate Kc when not all equilibrium concentrations are available.

Solution

1) because while Kc values we multiply and divide different concentrations of compounds... so while adding we get the Kc values by multiplying for eg

A-->B Kc1=B/A

C-->D Kc2=D/C

so A+C-->B+D Kc=B*D/A*C=Kc1*Kc2