Skip to main content
Ch.12 - Solids and Modern Material
Tro - Chemistry: A Molecular Approach 4th Edition
Tro4th EditionChemistry: A Molecular ApproachISBN: 9780134112831당신이 사용하는 게 아니라요?교과서 변경
모든 교과서Tro 4th EditionCh.12 - Solids and Modern Material문제 78
12장, 문제 78

Copper iodide crystallizes in the zinc blende structure. The sep- aration between nearest neighbor cations and anions is approximately 311 pm, and the melting point is 606 °C. Potassium chloride, by contrast, crystallizes in the rock salt structure. Even though the separation between nearest-neighbor cations and anions is greater (319 pm), the melting point of potassium chlo- ride is higher (776 °C). Explain.

검증된 단계별 안내
1
insert step 1> Understand the structures: Copper iodide (CuI) crystallizes in the zinc blende structure, which is a type of face-centered cubic lattice. Potassium chloride (KCl) crystallizes in the rock salt structure, which is also a face-centered cubic lattice but with a different arrangement of ions.
insert step 2> Consider the ionic interactions: In both structures, the melting point is influenced by the strength of the ionic bonds between the cations and anions. The strength of these interactions depends on the charge and size of the ions.
insert step 3> Compare ionic sizes and charges: Copper (Cu) and iodide (I) ions in CuI have different sizes and charges compared to potassium (K) and chloride (Cl) ions in KCl. The charge on Cu is +1 and on I is -1, similar to K and Cl, but the size and polarizability of the ions differ.
insert step 4> Analyze the effect of ionic size and polarizability: Although the separation between ions in KCl is greater, the larger size and higher polarizability of iodide ions in CuI can lead to weaker ionic interactions compared to the smaller and less polarizable chloride ions in KCl.
insert step 5> Conclude with melting point implications: The stronger ionic interactions in KCl, due to the smaller and less polarizable chloride ions, result in a higher melting point compared to CuI, despite the greater separation between ions in KCl.

비슷한 문제에 대한 검증된 영상 답변:

이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.
영상 길이:
2m
도움이 되었나요?

주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Ionic Bonding and Lattice Energy

Ionic bonding occurs between cations and anions, where the electrostatic attraction between oppositely charged ions leads to the formation of a crystalline lattice. Lattice energy, which is the energy released when gaseous ions form a solid ionic compound, is a key factor influencing the stability and melting point of ionic compounds. Higher lattice energy typically results in a higher melting point, as more energy is required to break the ionic bonds.
추천 영상:
가이드 코스
00:49
Lattice Energy

Crystal Structure Types

The arrangement of ions in a crystal lattice significantly affects the properties of ionic compounds. The zinc blende structure, adopted by copper iodide, features a tetrahedral coordination of ions, while the rock salt structure of potassium chloride has octahedral coordination. These structural differences influence the distances between ions and the overall stability of the lattice, impacting melting points.
추천 영상:
가이드 코스
02:29
Acid Structure and Types

Influence of Ionic Size and Charge

The size and charge of the ions involved in ionic compounds play a crucial role in determining their physical properties. In potassium chloride, the larger ionic radius of potassium compared to copper, along with the higher charge density of chloride, contributes to stronger ionic interactions. This can lead to a higher melting point despite the greater separation between nearest neighbors, as the overall electrostatic interactions in the lattice are stronger.
추천 영상:
가이드 코스
01:21
Factors Influencing Reaction Rates
관련 실천
교과서 질문

An unknown metal is found to have a density of 7.8748 g/cm3 and to crystallize in a body-centered cubic lattice. The edge of the unit cell is 0.28664 nm. Calculate the atomic mass of the metal.

2543
views
2
rank
교과서 질문

Saran, the polymer used to make saran wrap, is an addition polymer formed from two monomers—vinylidene chloride and vinyl chloride. Draw the structure of the polymer. (Hint: The monomers alternate.)

1335
views
1
rank
교과서 질문

Polyacrylonitrile (PAN) is an addition polymer with the struc- ture shown here. Draw the structure of the monomer.

1109
views
교과서 질문

The density of an unknown metal is 12.3 g/cm3, and its atomic radius is 0.134 nm. It has a face-centered cubic lattice. Find the atomic mass of this metal

2320
views
교과서 질문

Teflon is an addition polymer formed from the monomer shown here. Draw the structure of the polymer.

1018
views