Ideal Gas Equation and changes in variables
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Ideal Gas Equation and changes in variables
On the midterm I had a lot of trouble visualizing how a change in the different variables in the ideal gas equation would affect the rest of the variables. For example, how would a change in volume affect the other variables in PV=nRT? What about a change in pressure? Would a change in moles affect anything in particular? While I can understand applications of using the ideal gas equation, I'm lost when it comes to the theoretical scenarios in which there is no number to solve for.
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Re: Ideal Gas Equation and changes in variables
I think using the equation itself to determine the type of relationships between the variables is helpful. For example, the equation tells you that volume and pressure have an inverse relationship. Therefore, once you determine what type of an effect and increase in volume would have on a reaction, an increase in pressure would have the opposite effect. I hope this helps!
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Re: Ideal Gas Equation and changes in variables
Hi, I find that thinking about what is constant/what is changing helps me visualize how one variable changes another.
For example, PV = nRT means that pressure and volume multiplied together need to equal the other side, n*R*T. In a question where we decrease volume only, we're not changing anything else, so the right side of the equation (n*R*T) stays constant. This means that pressure has to increase in order to compensate for the decrease in volume because P*V still have to equal n*R*T.
I hope this helped!
For example, PV = nRT means that pressure and volume multiplied together need to equal the other side, n*R*T. In a question where we decrease volume only, we're not changing anything else, so the right side of the equation (n*R*T) stays constant. This means that pressure has to increase in order to compensate for the decrease in volume because P*V still have to equal n*R*T.
I hope this helped!
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Re: Ideal Gas Equation and changes in variables
Hi!
I find it helpful to look at the variables on each side of the PV=nRT equation to find their relationship. Since all of the variables are multiplied, variables on the same side of the equation will have inverse changes. For example, if the only change in the system is a decrease in volume, the pressure will have to increase in order to compensate and make the equation equal.
I find it helpful to look at the variables on each side of the PV=nRT equation to find their relationship. Since all of the variables are multiplied, variables on the same side of the equation will have inverse changes. For example, if the only change in the system is a decrease in volume, the pressure will have to increase in order to compensate and make the equation equal.
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Re: Ideal Gas Equation and changes in variables
Hi! I think it's helpful to look at both what side of the equation the variables are on, and what information is given to you in the problem/what you have to solve for. For example, if the volume is changing and the problem says you need to find out what happens to the pressure, then you would need to look at 2 things. The first thing to look for is if all the other variables stay the same. If the temperature and number of moles aren't changing, then you can individually analyze the relationship between pressure and volume. The second thing to look for is whether the variable is increasing or decreasing. If the volume is increasing, then to maintain the other variables as constants, the pressure would have to decrease, and vice versa. Hope this helps!
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Re: Ideal Gas Equation and changes in variables
Hello! In the ideal gas law, P = pressure, V = volume(L), n = moles, R = gas constant, and T = temperature, giving you the formula, PV=nRT. For example if the question is asking for pressure, we can manipulate the formula by dividing V to the other side in order to get P=(n/V)(RT). (n/V) is equal to concentration. So we get the modified formula, P=(concentration)(RT). Also if the question is asking for volume then we divide the P to the other side giving us, V=nRT/P. Hope this helps!
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