Question

How to solve the combined gas law formula?

Answer 1

Hint: The ideal gas law is also known as the combined gas law and is the resultant summation of Boyle’s law, Charles law, Gay-Lussac’s law, it connects the variable of one state of a gas to another state of the same gas or the variables of the same states to themselves holding true only for ideal gases and thus cannot be applied on solids or on real gases.

Complete step-by-step answer:
When we talk about combined gas law, we must know about what it exactly represents and what variables does it connect so the ideal gas equation is $ PV = nRT $ where
P represents Pressure
V represents Volume
T represents temperature
n represents number of moles
R represents the gas constant.
Thus, this equation connects four variables namely P, V, n, T.
So, if we are provided with three variables, we can always find the fourth one by using the ideal gas equation.
Another similar way, where combined gas law proves to be useful is when we are provided data on one state of the system and we need to find a relation between this state and another state
e.g., Say $ {P_1},{V_1},{T_1},{n_1} $ are variables of state $ - 1 $ now if we know at least three other variables in a different state of the same gas then we can calculate the missing variable and this uses the following formula:
 $ \dfrac{{{P_1}{V_1}{n_1}}}{{{T_1}}} = \dfrac{{{P_2}{V_2}{n_2}}}{{{T_2}}} $
There are the various ways by which we can solve the combined gas equation.

Note: While calculating always take temperature in Kelvin scale otherwise you will obtain a result full of errors also always be careful to use the same units of pressure on either side when using the second equation shown above for connecting two different states of ideal gas.