Residence Time of H2S in atmosphere

[Dynamic24]

Homework Statement

Using the table of atmospheric composition and residence time , calculate the rate of input for N2 and H2S.
Question 5 answers
A)N2: 4.1 x 1015 mol/yr; H2S: 9.6 x 1013 mol/yr
B)N2: 1.4 x 1014 mol/yr; H2S: 9.0 x 109 mol/yr
C)N2: 4.1 x 1015 mol/yr; H2S: 9.0 x 109 mol/yr
D)N2: 1.4 x 1014 mol/yr; H2S: 3.3 x 1012 mol/yr

Homework Equations

Residence time=N/R N=moles R= rate

Residence time for H2S(1day), H2S(conc)=.05ppb

The Attempt at a Solution

I found out the first part fine. I am having a hard time finding the rate of H2S. I started of converting ppb into grams and then getting the moles and dividing by the residence time in years. Any help would be great.

 

[nate808]

Hello,

To find the rate of H2S, you will need to use the concentration and residence time given in the problem. The concentration of H2S is given in parts per billion (ppb), so you will need to convert it to the appropriate units for moles. This can be done by using the molar mass of H2S (34.08 g/mol) and converting the ppb to grams using the density of air (1.225 kg/m3). Once you have the mass in grams, you can convert it to moles by dividing by the molar mass.

Once you have the number of moles, you can use the residence time (1 day) and convert it to years (365.25 days per year) to get the rate of input in moles per year. This will give you the answer in option B: N2: 1.4 x 1014 mol/yr; H2S: 9.0 x 109 mol/yr.

I hope this helps. Let me know if you have any further questions.

 

[Blueshift5]

The residence time of H2S in the atmosphere is dependent on various factors such as emissions, chemical reactions, and removal processes. The concentration of H2S in the atmosphere is relatively low (0.05 ppb) and it has a short residence time of 1 day. This indicates that the rate of input for H2S is relatively low compared to other gases in the atmosphere.

To calculate the rate of input for H2S, we can use the formula: Rate = (Concentration x Volume)/(Residence time). The concentration of H2S is given in parts per billion (ppb), so we first need to convert it to moles per liter (mol/L).

Concentration of H2S = 0.05 ppb = 0.05 x 10^-9 mol/L = 5 x 10^-11 mol/L

The volume of the atmosphere can be approximated as 4.2 x 10^18 L.

Using the given residence time of 1 day, we can convert it to years:

1 day = (1/365) years = 0.0027 years

Substituting these values into the formula, we get:

Rate = (5 x 10^-11 mol/L x 4.2 x 10^18 L)/(0.0027 years) = 7.4 x 10^7 mol/yr

Therefore, the rate of input for H2S in the atmosphere is approximately 7.4 x 10^7 mol/yr. This value is closest to option D, with a rate of 3.3 x 10^12 mol/yr which is significantly higher than the calculated value. This indicates that option D is not a correct answer.

In conclusion, the correct answer is option A, with a rate of 9.6 x 10^13 mol/yr for H2S. This value is significantly lower compared to the rate of input for N2, which is 4.1 x 10^15 mol/yr. This highlights the relatively low contribution of H2S to the overall composition of the atmosphere.