Question

QUESTION 3 In performing part B of the experiment, Claudia records the following data: Description Value Comments Mass Mg 0.0164 g Determination of moles Apparatus V Initial pressure Determination of volume 0.1920 L 743.2 mm Hg Determination of pressure Pressure after reaction 799.3 mm Hg Determination of temperature Water bath temperature 20.3 °C Calculate the experimental value of R based on Claudia's data. atm L mol 1 K-1

Answer 1

Moles of Mg, n = mass of Mg / molar mass of Mg= 0.0164 g/( 24.3 g/mol) = 0.000675 mol

volume, V = 0.192 L

Pressure = 799.3 mmHg - 746.2 mmHg

= 56.1 mmHg/ 760 atm

= 0.0738 atm

Temperature T = 20.3 oC = 20.3 + 273 K = 293.3 K

Then,

Substitute all the values in ideal gas equation

PV =nRT

R = PV/nT

= 0.0738 atm x 0.192 L /[ (0.000675 mol)(293.3 K)]

= 0.0715 atm L mol^-1 K^-1

R = 0.0715 atm L mol^-1 K^-1

Therefore,

Experimental value of R = 0.0715 atm L mol^-1 K^-1