Passage III

Gas effusion occurs when a gas moves through a tiny opening into a region of lower pressure. The rate in milliliters per second (mL/sec) is measured using the apparatus in Figure 1.

A 25 mL gas sample in a syringe freely escapes into a flask. The molecular mass, in a.m.u. (atomic mass units), for seven gases and the time required to completely effuse are recorded in Table 1. The densities (mass/volume) in grams per liter (g/L) and average molecular speed (average distance traveled by a molecule per second) in meters per second (m/sec) are also given.

Figure 2 shows a graph of the effusion rate versus the molecular mass of the gases.

18. According to Table 1, if a syringe of unknown volume is filled with H2 gas, and takes 15.3 sec for this H2 gas to effuse, which of the following measurements would the unknown volume of the syringe be closest to?

Answer and Explanation

Your Answer is

Correct Answer is J

Explanation

Looking at table 1, it takes 5.1 seconds for 25 ml of hydrogen to flow out completely, then 15.3 seconds is three times that of 5.1, and theoretically the outflow gas should also be three times, so 25*3=75, choose J