Question

On a day with a temperature of 15 ∘C and a pressure of 792.0 torr , how many grams of peroxyacyl nitrates are found in the air above Los Angeles (1500. km3) if the concentration is 30.0 ppb by moles? The molar mass of the major peroxyacyl nitrate, peroxyacetyl nitrate, is 118.03 g/mol.

Answer 1

Considering the ideal gas equation as:

where,

P is the pressure of the gas

V is the volume of the gas

n is the number of moles

R is gas constant

T is the temperature

The equation for the calculation of moles can be written as:

Given:

The values for air:

Volume = 1500 km³

The conversion of V(km³) to V(L) is shown below:

1 km³ = 1*10¹² L

So, Volume, V= 1500*10¹² L

Pressure = 792.0 torr

The conversion of P(torr) to P(atm) is shown below:

1 torr= (1/760)atm

So, Pressure, P = 792.0/760atm = 1.0421 atm

Temperature = 15 ⁰C

The conversion of T(⁰C) to T(K) is shown below:

T(K) = T(⁰C) + 273.15

So, the temperature, T = (15 + 273.15) K = 288.15 K

Also, R = 0.0821 atm.L/mol.K

Moles of air:

Given,

The concentration of peroxyacyl nitrate in the air = 30.0 ppb by moles

It means:

30 moles of peroxyacyl nitrate in 10⁹ moles of air.

Or can be written as:

10⁹ moles of air contains 30 moles of peroxyacyl nitrate

1 mole of air contains 30/10⁹ moles of peroxyacyl nitrate

So,

6.6*10¹³ mole of air contains (30/10⁹)*6.6*10¹³ moles of peroxyacyl nitrate

So, moles of peroxyacyl nitrate = 1.98*10⁶ moles

Moles can also be defined as:

To calculate the mass, the formula can be written as:

Also, given = 118.03 g/mol

So grams of peroxyacyl nitrate found in the air above Los Angeles are: