If equal masses of O2 and N2 are placed in identical containers at the same temperature, which of the following statements is (are) true?
a. both flasks contain the same number of molefules
b. the pressure in the N2 flask is greater than in the other container
c. there are more molecules in trhe O2 flask
d. this question cannot be answered unless we know the pressure in each flask.
e. none of the above are correct
The correct answer is e. none of the above are correct.
Explanation:
a. both flasks contain the same number of molecules - This statement is false because the two gases have different molecular weights. Oxygen (O2) has a molar mass of 32 g/mol, while nitrogen (N2) has a molar mass of 28 g/mol. Therefore, the number of molecules of each gas in the containers would not be the same.
b. the pressure in the N2 flask is greater than in the other container - This statement is false because the pressure of a gas depends on its temperature, volume, and number of moles. Since the temperature and volume are the same for both containers, the pressure will be equal if the number of moles is the same.
c. there are more molecules in the O2 flask - This statement is false as explained in answer a.
d. this question cannot be answered unless we know the pressure in each flask - This statement is false because the pressure is not a determining factor in this scenario. The key difference between oxygen and nitrogen is their molar mass, which affects the number of molecules present, not the pressure.
Therefore, the correct answer is e. none of the above are correct.
To determine which of the statements is true, we need to consider the ideal gas law, which states:
PV = nRT
where:
P = pressure
V = volume
n = number of moles
R = ideal gas constant
T = temperature
Since both flasks have identical containers and are at the same temperature, the volume (V) and temperature (T) factors are constant. Let's analyze each statement:
a. Both flasks contain the same number of molecules.
The number of moles (n) is directly proportional to the number of molecules. Since the masses of O2 and N2 are equal, and the molar mass of N2 is larger than that of O2, it means that the number of moles in the flask with N2 would be smaller to balance out the difference in molar masses. Thus, statement a is FALSE.
b. The pressure in the N2 flask is greater than in the other container.
According to the ideal gas law, the pressure is directly proportional to the number of moles. Since the number of moles in the N2 flask is smaller than in the O2 flask, the pressure in the N2 flask would be lower. Therefore, statement b is FALSE.
c. There are more molecules in the O2 flask.
As mentioned in the analysis for statement a, the number of moles in the N2 flask is smaller due to the larger molar mass of N2 compared to O2. Hence, statement c is FALSE.
d. This question cannot be answered unless we know the pressure in each flask.
Using the information provided, we can determine the relationship between the number of moles and pressure in each flask, and we can conclude that both statements a, b, and c are false based on that analysis. Thus, statement d is FALSE.
e. None of the above are correct.
Since all the statements provided (a, b, c, and d) are false, the correct answer is e. None of the above are correct.
You should be able to answer each of the questions from the following:
32 g is a mole of O2; 28 g is a mole of N2. Therefore, equal masses will contain more moles of N2.
PV = nRT
1 mole contains 6.02 x 10^23 molecules.