Density Of Water at 25degrees Celsius : 0.997044 Atmospheric Pressued used : 757

Question

Density Of Water at 25degrees Celsius : 0.997044

Atmospheric Pressued used : 757.7 mm Hg

Density of Dry Air used : .00193 g/cm3

Weight of flask used : 24.41g

Weight of flask with and CO2 : 24.425g

Weight of flask filled with water : 55.84g

a) First calculate the mass of CO2 in the flask.

b) Report your experimnetal molar mass of carbon dioxide.

c) Compare your reported value of the molar mass of carbon dioxide to the known value by calculating the % error.

d) You should also estimate your precision by using the result of the calculus of the propagation of error. The relative error in the molar mass is equal to the square root of the sum of the square of the relative errors in the measured mass, volume, temp, pressure, and the constant R (.08206). Start your calculation by deciding which of these terms under the radical can be ignored.

Density Of Water at 25degrees Celsius : 0.997044 Atmospheric Pressued used : 757.7 mm Hg Density of Dry Air used : .00193 g/cm3 Weight of flask used : 24.41g Weight of flask with and CO2 : 24.425g Weight of flask filled with water : 55.84g a) First calculate the mass of CO2 in the flask. b) Report your experimnetal molar mass of carbon dioxide. c) Compare your reported value of the molar mass of carbon dioxide to the known value by calculating the % error. d) You should also estimate your precision by using the result of the calculus of the propagation of error. The relative error in the molar mass is equal to the square root of the sum of the square of the relative errors in the measured mass, volume, temp, pressure, and the constant R (.08206). Start your calculation by deciding which of these terms under the radical can be ignored.

Explanation / Answer

a) Volume of flask = mass of water/ Density of water
= (55.84-24.41)/0.997044
= 31.52 ml

b) PV= nRT
P= 757.7 mm Hg = 0.997atm

V= m*D = (24.425-24.41)/0.00193 = 7.77 ml =0.0077 Lit
n= 24.425-24.41/Mw
R= 0.0821 L.atm.K-1.mol-1
T= 298 K

Mw of Co2 = WRT/PV = 0.015*0.0821*298/0.997*0.0077
= 47.373 g/mol

c) Molarmass of Co2 = 44 g/mol

Molarmass of Co2 observed = 47.373 g/mol

%error = 47.373-44/44*100 = 7.67

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