Consider the following graph. (a) If curves A and B refer to two different gases, He and O2, at the same temperature, which curve corresponds to He?

Video transcript

Hi everyone here we have a question asking us to consider the graph below comparing the velocity distribution of ph three and krypton at the same temperature, identify which curve represents krypton. So in the graph, the Y accesses the relative number of particles. While the X axis is the molecular speed, we can think of the molar mass of a gas as being related to the number of particles. One molar mass equals one particle. And we need to recall that the molecular speed of a gas is given by the molecular speed equals the square root Of three. R. T. Over. Em where R is r gas constant T. Is our temperature and m is the molar mass of the gas. We can see that the average speed is inversely proportional to the molar mass of a gas. A larger molar mass results in a lower average speed. This makes sense. Since you would expect a larger object to move slower than a smaller one. Our molar mass of ph three Equals 40 grams per mole. Our molar mass of krypton equals .8 g per mole. This means krypton is heavier and therefore slower and the curve will peak more to the lift. This means that our answer here is a thank you for watching. Bye