Lowest Average Speed of Gases at 25C: H2S

In summary, the average speed of gases at 25°C is determined by their molecular weight and the forces between molecules. H2S has a higher molecular weight than other common gases, resulting in a lower average speed at the same temperature. The average speed of gases at 25°C can be measured using the RMS speed formula, which takes into account temperature and molecular weight. As temperature increases, so does the average speed of gases. The lower average speed of H2S at 25°C affects its behavior, causing a slower rate of diffusion, as well as impacting its solubility and reactivity with other substances.
  • #1
Soaring Crane
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0
Which of the following gases has the lowest average speed at 25C?
a.NH3
b.O2
c.H2S
d.CH4
Is it H2S? Given the formula sqrt(3RT/M), is it not true that the gas with the greatest molar mass will have the lowest speed?
NH3 = 17.03 g/mol
O2 = 32 g/mol
H2S = 34.08 g/mol
CH4 = 16.04 g/mol
Thanks.
 
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  • #2
Yes, the KE of each molecule (at the same Temperature) is the same.
KE = ½ m v^2 = 3/2 k_B T
If you haven't seen it yet, k_B = k_Boltzmann = R/N_Avagadro
 
  • #3


Yes, it is correct that the gas with the greatest molar mass will have the lowest speed. In this case, H2S has the highest molar mass out of the options given, so it would have the lowest average speed at 25C. This is due to the relationship between molar mass and speed in the formula you provided (sqrt(3RT/M)). The heavier the gas, the slower its average speed will be at a given temperature. Therefore, H2S would have the lowest average speed at 25C out of the gases listed.
 

1. What causes gases to have different average speeds at 25°C?

The average speed of a gas at a given temperature is determined by its molecular weight, with lighter gases having higher average speeds than heavier gases at the same temperature. Additionally, the forces between gas molecules can also affect their average speed.

2. Why is the average speed of H2S at 25°C lower than other gases?

H2S (hydrogen sulfide) has a molecular weight of 34 g/mol, which is higher than most common gases such as oxygen (32 g/mol) and nitrogen (28 g/mol). This higher molecular weight results in a lower average speed at a given temperature.

3. How is the average speed of gases measured at 25°C?

The average speed of gases can be measured using the root-mean-square (RMS) speed formula, which takes into account the temperature and molecular weight of the gas. This formula is √(3RT/M), where R is the gas constant, T is the temperature in Kelvin, and M is the molar mass of the gas.

4. Can the average speed of gases change at different temperatures?

Yes, the average speed of gases is directly proportional to the temperature. As the temperature increases, the average speed of gas molecules also increases.

5. How does the average speed of H2S at 25°C impact its behavior?

The lower average speed of H2S at 25°C means that it will have a slower rate of diffusion compared to other gases at the same temperature. This also affects its solubility and reactivity with other substances at 25°C.

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