Question

At 20°C the vapor pressure of dry ice is 56.5 atm. If 10g of dry ice (solid CO2) is placed in an evacuated 0.25 L chamber at a constant 20°C, will all of the solid sublime?

Answer 1

Answer:

Pressure of the gas is greater than the vapor pressure, therefore all the solid will not sublime.

Explanation:

To solve this problem we use ideal gas equation.

PV =nRT

If Presure of the gas (P) is greater than vapor pressure (56.5 atm), all the solid will not sublime. But If P < 56.5 atm, all of it will sublime.

where;

P is pressure of the gas in atm

V is volume of gas in Litre

T is absolute temperature of the gas in Kelvin

n is number of gas moles

R is ideal gas constant or Boltzmann constant = 0.082057 L atm K⁻¹ mol⁻¹

Given T = 20 °C  = 273 + 20 = 293K

Volume = 0.25L

n = Reacting mas (m)/Molar mass(M)

Molar mass of CO₂ = 12 + (16X2) = 12+32 = 44g/mol

Reacting mass = 10g

n = m/M ⇒ 10/44

n = 0.2273

PV =nRT ⇒ P = nRT/V

P = (0.2273X0.082057 X293)/0.25

P = 21.8596 atm

Therefore, since Pressure of the gas is greater than the vapor pressure, all the solid will not sublime.