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Learning Gas Laws, and am confused regarding how to set up the problem to find the correct answer

When using the gas laws and you are given 3 out of the 4 items, how do you know which order to place them in to find the answer for each law? & Is this the same for each law?

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Cynthia P. | Math and ScienceTutor ExtraordinaireMath and ScienceTutor Extraordinaire

If you are using Charles or Boyles Law the process is the same as for the ideal gas law posted by Kandace C. You simply need to determine which variables you have and which one you are looking for,  then rearrange the equation for the variable you are looking for. 

Boyles Law: P1(V1) = P2(V2)  P=pressure, V=volume   To rearrange the variables in this equation, you divide both sides by the variable you are trying to move, essentially just moving it to the bottom of the other side... P1=(P2*V2)/V1

Charles Law: V1/T1 = V2/T2  V=volume, T=temperature   To rearrange for a volume, multiply both side by the T you are trying to move, essentially the T that it is partnered with moves to the top of the other side.  To solve for T it is a little more complicated... You need to start with the reciprocal of the equation and then solve the same way. V1= (V2 *T1) /T2           T1=(T2*V1)/V2

Kandace C. | The Chemistry Queen Providing Elite Math and Science TutoringThe Chemistry Queen Providing Elite Math...
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The ideal gas law is:


If given three of the four items, such as pressure (P), volume (V), and number of moles (n), you would rearrange the ideal gas law to solve for the missing quantity, temperature (T):


If given P, V, and T, rearranging the ideal gas law becomes:


If given, P, n, and T, rearranging the ideal gas law becomes:


If given V, n, and T, rearranging the ideal gas law becomes: