Dr Bob
Can you confirm please
Given a cylinder of fixed volume filled with one mole of Ar gas,which of the following is CORRECT?
(assume that all gases obey the ideal gas laws)
A: if the cylinder temp. is changed from 20 to 25 deg.C the pressure will double
B:a cylinder of identical volume filled with the same PRESSURE of He must contain more atoms of gas as He atoms are smaller than Ar atoms.
C:if a second mole of Ar is added to the cylinder, the ratio T/P would remain constant
D: two of the above
E: none of the above
I think its E none of the above..after scouring through the text book for way to many hours I have reached the conclusion that if all the gases obey the same ideal gas law ....then none can be right!!!
Am I correct please in my thoughts?
Thanks Andy
I would go with E.
Thanks Dr Bob
You rock!!!!
Andy
Hello Andy! It seems like you've thought through the question quite thoroughly. Let's break down each statement and see if your conclusion is correct.
Statement A: "If the cylinder's temperature is changed from 20 to 25 degrees Celsius, the pressure will double."
To determine if this statement is correct, we can use the ideal gas law, which states that PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the gas constant, and T is the temperature. Since the volume is fixed and the number of moles is given as one mole, the equation becomes P1/T1 = P2/T2. Assuming the pressure and moles are constant, this equation can be rearranged to get P2 = (T2/T1) * P1. In this case, if the temperature is changed from 20 to 25 degrees Celsius, the pressure will not double because the temperature ratio (T2/T1) in the equation is less than two. Therefore, Statement A is incorrect.
Statement B: "A cylinder of identical volume filled with the same pressure of He must contain more atoms of gas as He atoms are smaller than Ar atoms."
This statement is incorrect. The number of atoms or molecules in a gas is determined by Avogadro's law, which states that equal volumes of gases at the same temperature and pressure contain an equal number of particles. Since both cylinders have the same volume and pressure, they must contain the same number of particles (atoms or molecules) according to Avogadro's law. Therefore, Statement B is incorrect.
Statement C: "If a second mole of Ar is added to the cylinder, the ratio T/P would remain constant."
To determine if this statement is correct, we can again use the ideal gas law equation. Assuming the volume is constant, the equation becomes P1/T1 = P2/T2. If a second mole of Ar is added to the cylinder, the number of moles will increase, which means the pressure must also increase to maintain the same ratio of T/P. Therefore, Statement C is incorrect.
Based on the analysis of each statement, it appears that your initial conclusion is correct. None of the statements A, B, or C are correct. Therefore, the correct answer is E: none of the above.
I hope this explanation helps clarify things for you! If you have any further questions, feel free to ask.