Question

Dry ice is solid carbon dioxide. A 1.75−g sample of dry ice is placed in an evacuated 4.57−L vessel at 20.0°C. Calculate the pressure inside the vessel after all the dry ice has been converted to CO2 gas.

Answer 1

i) Determine the number of moles of CO2

Dry ice is solid form of CO2

number of moles = Mass /Molar mass

mass of CO2 = 1.75g

Molar mass of CO2 = 44.01g

substituting the values

Number of moles of CO2 = 12.01g/44.01g/mol = 0.27289mol

ii) Detemine the pressure of CO2 using ideal gas law

Ideal gas law is follows

PV = nRT

where,

P = Pressure, ?

V = Volume , 4.57 L

T = Temperature, 293.15K ( ℃ should be converted into Kelvin unit while applying Ideal gas equation , 0℃ = 273.15K)

n = Number of moles , as calculated above it is 0.27289mol

R = gas constant, 0.082057(L atm/mol K)

rearranging ideal gas equation

P = nRT /V

substituting the values

P = 0.27289mol × 0.082057(L atm/mol K) × 293.15K/4.57L

P = 1.44atm