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10 gram sample of CHOH, at 30°C (vapor pressure 53.5 mm Hg) is sealed in a 5 Lit

ID: 593066 • Letter: 1

Question

10 gram sample of CHOH, at 30°C (vapor pressure 53.5 mm Hg) is sealed in a 5 Liter. ow many grams of liquid remain after the liquid-vapor equilibrium is established? Water has a heat of vaporization of hat would the temperature of water boiling in a pressure cooker at 40,900 J mok K and a normal boiling point of 1000. atmospheres be? fi 2.25 )Chloroform, CH,CL, has a vapor pressure of 197 mm Hg at 23 C and 448 mm Hg at 45'c hat is the heat of vaporization? Lead crystallizes in a face centered cubic cell and has a radius of 181 pm. What is the density f lead?

Explanation / Answer

Molar mass of methanol CH3OH is 32 g/gmol, you have a vapor pressure of 53.55 mm Hg

we know that 1 atm has 760 mm Hg so

53.55 / 760 = 0.07046 atm, we also know we have a volume of 5 liters so we can apply the ideal gas equation

PV = n RT, where p is pressure, V is volume, n is moles, R is the gas constant, T is temperature in Kelvin

0.0746 * 5 = moles * 0.082 * (30+273) , temperature is 30 Celsius, add 273 to get Kelvin

n = 0.0746 * 5 / ( 0.082 * 303) = 0.015 moles of ethanol in the vapor phase

moles = mass / molar mass so we can say that mass = moles * molar mass

mass of vapor = 0.015 * 32 = 0.48 grams so, you originally had 10 grams

10 - 0.48 = 9.52 grams , this is the mass left in the liquid phase