Exam 11: Intermolecular Forces and Liquids and Solids

Calculate the amount of enthalpy required to heat 25.0 g of solid benzene (C₆H₆)at -10°C to liquid benzene at 20.0°C. Thermodynamic data for benzene: specific heat of solid benzene = 1.52 J/g·°C; specific heat of liquid benzene = 1.73 J/g·°C; melting point = 5.5°C; $\Delta$ H_fus = 9.9 kJ/mol.

Acetic acid has a heat of fusion of 10.8 kJ/mol and a heat of vaporization of 24.3 kJ/mol.What is the expected value for the heat of sublimation of acetic acid?

Indicate all the types of intermolecular forces of attraction in He(l).

The fact that the density of ice is less than the density of liquid water is due to the formation of hydrogen bonds.

Palladium crystallizes in a face-centered cubic unit cell. Its density is 12.0 g/cm³ at 27°C.Calculate the atomic radius of Pd.

Of the given pair of compounds, which would have the higher boiling point? C₃H₈ or CH₃OCH₃

Potassium bromide, KBr, crystallizes like NaCl in a face-centered lattice. The ionic radii of K⁺ and Br^- ions are 133 pm and 195 pm, respectively. Assuming that all Br^- ions are positioned in the face and corners of the unit cell, while the K⁺ ions are positioned along the edge alternating between anions, calculate the length of a unit cell edge.

The mineral manganosite, manganese(II)oxide, crystallizes in the rock salt structure (the face-centered structure adopted by NaCl)with a density of 5.365 g/cm³. Find the unit cell edge length of manganosite.

Find the temperature at which water boils on a day in the mountains when the barometric pressure is 593 mmHg.(Given: the heat of vaporization of water is 40.79 kJ/mol)

The molar enthalpy of vaporization of carbon disulfide is 26.74 kJ/mol, and its normal boiling point is 46°C. What is the vapor pressure of CS₂ at 0°C?

Magnesium oxide, MgO, melts at 2,800°C and is very hard.The liquid conducts electricity very well.What kind of crystal is this?

Which of the following gases would have the highest critical temperature?

An example of a covalent network solid is

Solid iodine has a vapor pressure of 1.0 mmHg at 39°C. How many moles of iodine will sublime into a 500.mL flask at this temperature? If the volume of the flask is doubled at constant temperature, what will happen to the equilibrium vapor pressure of I₂? (Assume some solid I₂ is always present in the container.)

Which one of the following is an example of a covalent network solid?

Ethanol and dimethyl ether have the same molecular formula, C₂H₆O.Ethanol boils at 78.4°C.Dimethyl ether boils at -23.7°C.Their structural formulas are, respectively, CH₃CH₂OH and CH₃OCH₃. Explain why the boiling point of the ether is so much lower than the boiling point of ethanol.

Which one of the following substances is expected to have the highest boiling point?

Indicate all the types of intermolecular forces of attraction in SO₂(l).

Polyethylene plastic consists of long chains of carbon atoms, each of which is also bonded to hydrogens as shown below: Water forms beads when placed on a polyethylene surface.Why?

Given the following compound and its boiling point, identify whether it is polar or nonpolar: HCl, -84.9°C.