Question

C₂Hg H H H 9 H H H H H H-CC-C-C-CH й н н и Н Pentane H-C-C- C- HHH Propane CH₃OH :: H-c-9- H9-- HH Methanol Methanoic (formie) acid Methanal (formaldehyde) 때 애 H A CHO CH₂O Use the Lewis structures above to answer the following questions, a. Which substance, pentane or propane, would have the highest boiling point? Justify your answer in terms of intermolecular forces. b. Which substance, methanol or methanal, would have the highest vapor pressure? Justify your answer in terms of intermolecular forces. c. What is the hybridization for the carbon in methanoic acid? In an experiment, a student places 5.00 g of liquid methanol in a previously evacuated, rigid 500. mL container and allows the methanol to completely vaporize at 50.0 °C. d. Calculate the pressure of the methanol gas in the 500. mL container. e. If the sample of methanol gas is heated until the temperature is 100.°C, describe what changes, if any, would occur for the following values and justify your answers: i. Kinetic energy of methanol gas ii. Density of the methanol gas sample iii. Pressure of the methanol gas sample

This is NOT organic chemistry. this is a question I have on my review for the AP Chemistry.

Answer 1

3 a) Propane and pentane both have only dispersion force as the intermolecular force. Molecular weight of pentane is more than that of propane, hence pentane has more surface area and has more dipersion force .

Hence pentane has more boiling point than propane.

b)Higher the intermolecular force lower the vapor pressure. Methanol has intermolecular hydrogen bonding ,which is stronger than dipole dipole interaction present in methanal.

Hence methanal has higher vapor pressure than methanol

c) Carbon in methanoic acid has 1 double bond and 2 single bonds. Hence carbon is sp2 hybridised.

d) Ideal gas equation is PV=nRT

n= Moles = mass/Molar mass = 5g/32.04g/mol =0.156 mol

T = 273+50 =323 K

P=nRT/V = (0.156mol x 0.0821Latm/mol K x 323K)/0.5L = 8.27 atm

Pressure = 8.27 atm

e) i) When temperature of methanol is increased velocity and hence collision between the gas molecule increases.As a result kinetic energy of methanol increases

ii)Density of a gas is number of molecules per unit volume of the gas. When temperature increases volume of the gas increases and hence density decreases

iii) Pressure of a gas depends on the collision of gas molecules on the wall of the container. When temperature increases coliision increases and hence pressure of the gas increases