1. Calculate the total mass (in kg) of nitrogen, oxygen, and carbon dioxide gase
ID: 539548 • Letter: 1
Question
1. Calculate the total mass (in kg) of nitrogen, oxygen, and carbon dioxide gases in the atmosphere. Assume that the total mass of air in the atmosphere is 5.25 x 1021 g.
Mass of N2= ___× 10___kg
Mass of O2= ___× 10___kg
Mass of CO2= ____× ___10kg
Compositions of dry air at sea level:
2. On a smoggy day in a certain city, the ozone concentration was 0.54 ppm by volume. Calculate the partial pressure of ozone (in atm) and the number of ozone molecules per liter of air if the temperature and pressure were 20.0°C and 748 mmHg, respectively. Enter your answers in scientific notation.
___×10__atm
___×10___molecules /L
3.
The bond energy of N2 is 160 kJ/mol. What is the wavelength of a photon that can cause the dissociation of a N2 molecule? (h = 6.63 × 10–34J s; c = 3.0 × 108m/s and Avogadro's number = 6.022 × 1023 molecules/mole)
749 nm
366 nm
233 nm
375 nm
650 nm
4.
Peroxyacetyl nitrate (PAN) undergoes thermal decomposition as follows:
CH3(CO)OONO2 CH3(CO)OO + NO2
The rate constant is 3.0 × 104 s1 at 25°C. At the boundary between the troposphere and stratosphere, where the temperature is about 40°C, the rate constant is reduced to 2.6 × 107 s1.
(a) Calculate the activation energy for the decomposition of PAN.
____kJ/mol
(b) What is the half-life of the reaction (in min) at 25°C?
___ min
5.An electric power station annually burns 6.2 × 107 kg of coal containing 2.4 percent sulfur by mass. Calculate the volume of SO2emitted at STP.
V = ___×10___ L (Enter your answer in scientific notation.)
(% by Volume) N2 78.03 O2 20.99 Ar 0.94 CO2 0.033 Ne 0.0015 He 0.000524 Kr 0.00014 Xe 0.000006
Explanation / Answer
1. Mass of air = 5.21 * 10^21 g
We know that,
Density of air = 1.225 * 10^-3 g/ cm3
Volume of air = 5.21 * 10^21 / 1.225 * 10^-3
= 4.253 * 10^24 cm3
= 4.253 * 10^18 m3
Composition of N2 = 78.03 % by volume
Volume of N2 in air = 0.7803 * 4.253 * 10^18 m3
= 3.318 * 10^18 m3
Density of N2 = 1.2506 kg/m3
Mass of N2 in air = 1.2506 * 3.318 * 10^18
= 4.15 * 10^18 kg
Composition of O2 = 20.99 % by volume
Volume of O2 in air = 0.2099 * 4.253 * 10^18 m3
= 0.893 * 10^18 m3
Density of O2 = 1.429 kg/m3
Mass of O2 in air = 1.429 * 0.893 * 10^18
= 1.276 * 10^18 kg
Composition of CO2 = 0.033 % by volume
Volume of CO2 in air = 0.00033 * 4.253 * 10^18 m3
= 0.00140 * 10^18 m3
Density of CO2 = 1.977 kg/m3
Mass of CO2 in air = 1.977 * 0.00140 * 10^18
= 2.76 * 10^15 kg
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