Exam 12: Intermolecular Forces: Liquids,solids,and Phase Changes

Liquid ammonia (boiling point = -33.4°C)can be used as a refrigerant and heat transfer fluid.How much energy is needed to heat 25.0 g of NH₃(l)from -65.0°C to -12.0°C?

Polonium crystallizes in the simple cubic lattice.What is the coordination number for Po?

Use molecular orbital band diagrams to explain why metals are good conductors but semiconductors are not.

The energy gap between the conduction band and the valence band is large for

Consider the phase diagram shown below. a.What phase(s)is/are present at point A? b.What phase(s)is/are present at point B? c.Name point C and explain its significance. d.Starting at D,if the pressure is lowered while the temperature remains constant,describe what will happen.

Examine the following phase diagram and identify the feature represented by point B.

Which one of the following substances does not exist in the indicated solid type?

The energy needed to increase the surface area of a liquid is

Iron has a body-centered cubic unit cell,and a density of 7.87 g/cm³.Calculate the edge length of the unit cell,in pm.(The atomic mass of iron is 55.85 amu.Also,1 amu = 1.661 $\times$ 10^-24g. )

Of the five major types of crystalline solid,which would you expect each of the following to form? (e.g. ,H₂O: molecular) a.Sn b.Si c.KCl d.Xe e.F₂

a.State the essential requirements for hydrogen bonding to be important in a compound. b.List four properties of water which are significantly influenced by the presence of hydrogen bonding.

Which of the following pairs is arranged with the particle of higher polarizability listed first?

A metal such as chromium in the face-centered cubic lattice will have ________________ atom(s)per unit cell.

Draw a fully labeled phase diagram (P versus T)of a substance whose solid phase can melt due to applied pressure (i.e. ,solid is less dense than liquid).Clearly label the triple point and the critical temperature on your diagram.

When liquid bromine is cooled to form a solid,which of the following types of solid would it form?

A metal in the simple cubic lattice will have ________________ atom(s)per unit cell.

Which of the following should have the highest surface tension at a given temperature?

Strontium metal crystallizes in a cubic unit cell which has an edge length of 612 pm.If the mass of an atom of Sr is 87.62 amu,and the density of Sr metal is 2.54 g/cm³,calculate the number of atoms per unit cell.(1 amu = 1.661 $\times$ 10^-24 g. )

The highest temperature at which superconductivity has been achieved is approximately

Ammonia's unusually high melting point is the result of