The estimated average concentration of NO2 in air in the United States in 2006 w

Question

The estimated average concentration of NO2 in air in the United States in 2006 was 0.016 ppm.

Calculate the partial pressure of the NO2 in a sample of this air when the atmospheric pressure is 752 torr (100 kPa ).

Express your answer using two significant figures.

1.2×105

Correct

Part B

How many molecules of NO2 are present under these conditions at 24 C in a room that measures 16 × 14 × 6 ft ?

Express your answer using two significant figures.

JUST NEED ANSWER FOR PART B

1.2×105

Explanation / Answer

B)

volume of room = 16 x 14 x 6 = 1344 ft3

now

1 ft = 30.48 cm

so

volume = 1344 x ( 30.48 cm)^3

volume = 3.805784182 x 10^7 cm3

now

we know that

1 L = 1000 cm3

so

volume = 3.805784182 x 10^7 x 10-3 L

volume = 3.805784182 x 10^4 L

now

we know that

PV = nRT

given

pressure = ( 1.2 x 10-5 / 760) atm

R = 0.0821

T = 24 C = 297 K

so

(1.2 x 10-5 / 760) x 3.805784182 x 10^4 = n x 0.0821 x 297

n = 2.4644 x 10-5

so

moles of N02 = 2.4644 x 10-5

now

number of molecules = moles x 6.023 x 10^23

so

number of molecules of N02 = 2.4644 x 10-5 x 6.023 x 10^23

number of molecules of N02 = 1.4843 x 10^19

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