Homework

# Solid States and Phases of Matter

## Chapter 12: 4-7 Homework

Textbook assignment: Read Kotz and Triechel, Chemistry and Chemical Reactivity Chapter 12: Sections 4-7.

##### Study Notes
• 12.4 Band theory is used ot explain high melting points, delocalized bonding between atoms, and conductivity in metals. Since more orbitals are available than there are electrons to fill them, electrons can move relatively easily from one energy level to another and from one atom to another. These bands are not completely continuous, however, and the energy required to make jumps between them explained the behavior of semiconductors, which underlies modern electronics and computer technologies.
• 12.5 Other kinds of solids: Molecular, Network, and Amorphous: Molecules tend to form solids based on their dispersion forces. Network solids are hard, rigid, three dimensional arrays of covalently bonded atoms. As with ions, these are extensions of atomic arrays, not molecules. Similarly, amorphous solids are collections of atoms, but their organization is irregular, with long and short bonds. As a result, amorphous solids melt slowly over a range of temperatures.
• 12.6 Phase Changes Involving Solids: The enthalpy of fusion is the amount of heat absorbed as a solid changes to a liquid state. The enthalpy of crystallization is the amount of heat given off or "evolved" when a substance freezes. For a given substance the enthalpy of fusion is equal to the enthalpy of crystallization, the only difference is the direction of heat flow.
• 12.7 Phase Diagrams: One common way to represent how solid, liquid, and gas states can co-exist is to use a phase diagram plotting the state as a function of pressure and temperature. The shape of the curve and the slope of the interface between solid and liquid states reflect the density properties of the substance. Because water is denser in the liquid state than in the solid state, its liquid-solid equilibrium line has a negative slope.

#### Key Formula

There are no new formulae for these sections.

#### Web Lecture

Read the following weblecture before chat: Lattices and Phase Changes

#### Videos for Chapter 12: The Solid State

Review the Videos at Thinkwell Video Lessons.

• Under "Chemistry of Metals"
• An Introduction to Metals
• Band Theory of Conductivity
• Intrinsic Semiconductors
• Doped Semiconductors

Work through the animations on Band Gap at the PVCDROM site to see how the band gap explanation accounts for movement of electrons in conductors.

#### Chat Preparation Activities

• Essay question: The Moodle forum for the session will assign a specific study question for you to prepare for chat. You need to read this question and post your answer before chat starts for this session.
• Mastery Exercise: The Moodle Mastery exercise for the chapter will contain sections related to our chat topic. Try to complete these before the chat starts, so that you can ask questions.

#### Chapter Quiz

• Required: Complete the Mastery exercise with a passing score of 85% or better.
• Go to the Moodle and take the quiz for this chapter.

#### (Aligns to) AP #9 GUIDED INQUIRY — Measuring the dependence of reaction rates on temperature, surface area, concentration, and catalysts -- Phase III

Write your formal report on this experiment. Be sure to include any graphs of data and error analysis that you performed.

References:

• AP2009 12 Determination of the Rate of a reaction and its order
• APGIE Investigation 10 Kinetics: Rate of Reaction: How Long Will that Marble Statue Last?
• IGHCE Lab 12.1-4 Determination of the effect of Temperature, Surface Area, and Catalysts on Reaction Rates
• IGHCE Lab 12.2 Determination of the effect of Surface Area on Reaction Rate