Question

PLEASE ANSWER ALL

1) The pressure of the atmosphere decreases with increasing altitude in the

Choose all that apply.

mesosphere

The pressure never decreases with increasing altitude.

thermosphere

stratosphere

troposphere

2)

If you were travelling outward from the earth in a space shuttle at an altitude of 79.6 km you would be in the ______.

3a) The gas, nitrogen, is found in dry air at sea level at a concentration of 78.1 percent by volume. What is the concentration of N₂ expressed in ppm? ______ppm

3b) The gas, krypton, is found in dry air at sea level at a concentration of 1.00 ppm. At a pressure of 753 mm Hg and a temperature of 27.8 °C, dry air contains about 2.46×10¹³ million molecules per cm³. The number of grams of krypton found in 1 cm³ of dry air at this temperature and pressure is ______grams.

3c) The gas, carbon monoxide, is found in dry air at sea level at a concentration of 1.00×10^-5 percent by volume. What is the concentration of COexpressed in ppb? _____ppb

Answer 1

1. As the altitude increases the pressure decreases so if we are starting from the lowest layer i.e. troposphere the pressure will go on decreasing

2. Mesosphere as mesosphere extends from about 50 to 85 km above the earth's surface

3. % Concentration = ppm / 10,000

as one part per million means 1 in a million, so: 1 ppm = 1/10⁶

and 1% = 1 / 100 = 0.01

so, 1% of a million = 0.01 x 1,000,000 = 10,000 ppm

(a) for 78.1 % N₂

ppm = 78.1 X 10,000

Concentration of N₂ = 7.81 X 10⁵ ppm

(b) 2.46×10¹³ million molecules per cm³ = 2.46×10¹⁹  molecules per cm³

we are given that concentration of krypton is 1 ppm

it means in 1 million molecule one will be of krypton

so, out of 2.46×10¹⁹ molecule 2.46×10¹³ will be of Krypton

now, 6.022 X 10²³ molecules = 1 mole

so 2.46 X  10¹³ will contain = [1/(6.023X10²³)] X (2.46X 10¹³) = 0.4085 X 10^-10 moles

also, number of moles = mass / molar mass

mass = (0.4085 X 10^-10 ) moles X 83.798 g/mol = 34.23 X10^-10 g

(c) 1 ppb = 1x10^-9 = 1000 ppm and concentration of CO = 10^-5 %

% Concentration = ppm / 10,000

ppm = 10^-5 X 10⁴ = 0.1

0.1 ppm = 0.1 X 10^-3 = 10^-4 ppb

​​​​​​​hope this helps! don't fprget to upvote:)