Gases Quiz 1

Explanation
When a glass column filled with mercury is inverted in a pool of mercury, the height of the mercury column stabilizes at 735 mm. This height represents the pressure exerted by the atmosphere, known as atmospheric pressure. To convert this height to atm, we use the conversion factor of 1 atm = 760 mmHg. Therefore, the atmospheric pressure is calculated as 735 mm / 760 mmHg = 0.967 atm.

Explanation
The number of molecules in a gas is directly proportional to the number of moles of the gas. Since all three flasks have the same volume and are at the same temperature and pressure (STP), the ideal gas law can be used to determine the number of moles in each flask. The ideal gas law states that PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the ideal gas constant, and T is temperature. Since all three flasks have the same volume, pressure, and temperature, the number of moles in each flask is the same. Therefore, all three flasks contain the same number of molecules.

Explanation
The molecules in flask C, which contains N2 gas, are least polar and therefore most ideal in behavior. This is because N2 is a diatomic molecule composed of two nitrogen atoms, which have similar electronegativities and do not have any significant difference in their electron distribution. As a result, N2 molecules do not have a permanent dipole moment and exhibit nonpolar behavior. In contrast, NH3 and NO2 molecules in flasks A and B, respectively, have polar bonds due to differences in electronegativity between the atoms involved, resulting in a permanent dipole moment.

Explanation
The molecules in flask A have the highest average velocity because ammonia (NH3) gas has a lower molar mass compared to nitrogen dioxide (NO2) gas and nitrogen (N2) gas. According to the kinetic theory of gases, the average velocity of gas molecules is inversely proportional to the square root of their molar mass. Therefore, since ammonia has the lowest molar mass among the three gases, its molecules will have the highest average velocity.

Explanation
The average kinetic energy of gas molecules is directly proportional to the temperature of the gas. Since all three flasks are at STP (standard temperature and pressure), they are at the same temperature. Therefore, the molecules in all three flasks have the same average kinetic energy.

Explanation
Flask A contains the fewest atoms because it is filled with the gas NO, which consists of only one nitrogen atom and one oxygen atom per molecule. Flask B contains NO2, which has one nitrogen atom and two oxygen atoms per molecule. Flask C contains N2O, which has two nitrogen atoms and one oxygen atom per molecule. Therefore, flask A has the fewest atoms.

Explanation
Since the question states that each flask is filled with a different gas, and each flask contains 1 liter of gas, it is not possible for any flask to contain 1.0 mole of gas. The number of moles of gas in a given volume depends on the molar mass of the gas. Since the molar masses of NO, NO2, and N2O are different, the number of moles of gas in each flask will be different. Therefore, none of the flasks contain 1.0 mole of gas.

Explanation
Flask C contains dinitrogen oxide (N2O). This is because flask C is filled with N2O, which is the chemical formula for dinitrogen oxide. Flask A contains NO, which is nitric oxide, and flask B contains NO2, which is nitrogen dioxide. Therefore, only flask C contains dinitrogen oxide.

Explanation
The question states that each flask contains a different gas, CH4 in flask A, CO2 in flask B, and C2H6 in flask C. It also states that there is 0.039 mole of gas. However, it does not specify which gas the 0.039 mole belongs to. Therefore, we cannot determine which flask contains the 0.039 mole of gas. Hence, the answer is none.

Explanation
The mass of a gas is determined by its molar mass, which is the highest for CO2 (flask B) among the given options. The average velocity of gas molecules is determined by the temperature and molar mass, with lighter molecules having higher average velocities. CH4 (flask A) has the lowest molar mass, so its molecules will have the highest average velocity. The kinetic energy of gas molecules is directly proportional to their temperature. Since all the flasks are at the same temperature, they will have the same kinetic energy. Therefore, there is no single flask that has the greatest mass, greatest average velocity, and highest kinetic energy.