Samples of helium gas and argon gas are each held at 400 K in separate but identical…
CHEMISTRY · Multi-part · A Level · Chemistry · Amount of substance · Amount of substance
Problem
Samples of helium gas and argon gas are each held at 400 K in separate but identical rigid containers. Each container holds the same number of moles of its respective gas. (Molar masses: He = 4.00 g mol−1, Ar = 39.9 g mol−1.)
(a) Identify which gas has the greater root-mean-square molecular speed at 400 K and justify your answer qualitatively.
(b) Calculate the ratio vrms(He)/vrms(Ar) at 400 K.
(c) If both gases were cooled to 200 K, explain whether the numerical ratio found in part (b) would increase, decrease, or remain the same. Support your explanation with appropriate reasoning.