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Homework 1 1. Dibutyl phthalate is often used as a manometer fluid. Its density

ID: 575012 • Letter: H

Question

Homework 1 1. Dibutyl phthalate is often used as a manometer fluid. Its density is 1.047 g/cm. What is the relationship between spms u and the pressur in or (25 points) 2. An ideal gas occupies a volume of 0.300 dm at a pressure of 1.60103 Pa. What is the volume of the gas maintained at the same temperature if the pressure is reduced to 1.25105 Pa? (25 points) 3. The density of a gas at 101.325 kPa and 298.15 K is 1.359 g/dm3. Assuming that the gas behaves as an ideal gas, calculate its molar mass. (25 points) 4. What are the mole fractions and partial pressures of each gas in a 2.50-L container into which 100.00 g of nitrogen and 200.00 g of carbon dioxide are added at 25? What is the total pressure? (25 points)

Explanation / Answer

1. Relation between height and pressure

Pressure = pgh = density of liquid x gravity constant x height

h = 1 mm = 0.001 meter

p = 1.047 g/cm^3 = 1047 kg/m^3

g = 9.81 m/s^2

feeding,

Pressure = 1047 x 9.81 x 0.001 = 10.2711 Pa = 0.077 torr

2. using ideal gas law,

P1V1 = P2V2

with,

P1 and V1 are initial pressure and volumes

P2 and V2 are final pressure and volumes when pressure is reduced

new Volume (V2) = 0.3 dm^3 x 1.6010^5 Pa/1.2510^5 Pa = 0.384 dm^3

3. with,

Pressure (P) = 101.325 KPa = 1 atm

Temperature (T) = 298.15 K

density (p) = 1.359 g/dm^3 = 1.359 g/L

R = gas constant

using relation,

molar mass = pRT/P

                    = 1.359 x 0.08205 x 298.15/1

                    = 33.2455 g/mol

4. moles N2 = 100 g/28 g/mol = 3.6 mol

moles CO2 = 200 g/44 g/mol = 4.5 mol

Total moles = 8.1 mol

mole fraction N2 = 3.6/8.1 = 0.44

mole fraction CO2 = 1-0.44 = 0.56

Temperature = 25 + 273 = 298 K

R = gas constant

Volume (V) = 2.50 L

total pressure = nRT/V

total pressure = 8.1 x 0.08205 x 2.50/2.50 = 79.2 atm

Partial pressure N2 = 0.44 x 79.2 = 34.85 atm

Partial pressure CO2 = 0.56 x 79.2 = 44.35 atm