Question

five samples of argon gas are described in the table below. rank the samples in order of increasing average kinetic energy of the atoms in them. that is, select \1\ next to the sample in which the argon atoms have the lowest average kinetic energy. select \2\ next to the sample in which the argon atoms have the next lowest average kinetic energy, and so on.

sample
2.4 mol	2.9 atm	11. °c	select
2.1 mol	1.9 atm	−6. °c	select
1.8 mol	1.6 atm	−28. °c	select
2.7 mol	1.1 atm	3. °c	select
1.7 mol	2.2 atm	−9. °c	select

Explanation:

Step1: Recall KE-temperature relation

Average kinetic energy (KE) of gas atoms depends only on absolute temperature (Kelvin), not amount/pressure. $\overline{KE} \propto T(K)$.

Step2: Convert °C to Kelvin

$T(K) = T(^\circ C) + 273.15$:

• 11°C: $11 + 273.15 = 284.15\ K$
• -6°C: $-6 + 273.15 = 267.15\ K$
• -28°C: $-28 + 273.15 = 245.15\ K$
• 3°C: $3 + 273.15 = 276.15\ K$
• -9°C: $-9 + 273.15 = 264.15\ K$

Step3: Order by increasing T(K)

Ranks (1=lowest KE):

• -28°C (245.15K): 1
• -9°C (264.15K): 2
• -6°C (267.15K): 3
• 3°C (276.15K): 4
• 11°C (284.15K): 5

Answer:

• 2.4 mol, 2.9 atm, 11.°C: 5
• 2.1 mol, 1.9 atm, -6.°C: 3
• 1.8 mol, 1.6 atm, -28.°C: 1
• 2.7 mol, 1.1 atm, 3.°C: 4
• 1.7 mol, 2.2 atm, -9.°C: 2