Question 1

X-ray diffraction measurements on a newly discovered crystalline form of element X revealed that X crystallizes in a body-centered cubic lattice in which the unit cell edge length is 304.6 picometers. Calculate the atomic radius of the X atoms in this crystal, based on the assumption that the atoms are tightly packed in the unit cell.Hint: Find the length of the cell body diagonal using the Pythagorean theorem.

Accepted Answer

The answer of X-ray diffraction measurements on a newly discovered...

Question 2

X-ray diffraction measurements on a newly discovered crystalline form of Eu revealed that Eu crystallizes in a body-centered cubic lattice in which the unit cell edge length is 458.3 picometers. Calculate the atomic radius of the Eu atoms in this crystal, based on the assumption that the atoms are tightly packed in the unit cell.Hint: Find the length of the cell body diagonal using the Pythagorean theorem.

Accepted Answer

The answer of X-ray diffraction measurements on a newly discovered...

Question 3

X-ray diffraction measurements on a newly discovered crystalline form of La revealed that La crystallizes in a body-centered cubic lattice in which the unit cell edge length is 426.3 picometers. Calculate the atomic radius of the La atoms in this crystal, based on the assumption that the atoms are tightly packed in the unit cell.Hint: Find the length of the cell body diagonal using the Pythagorean theorem.

Accepted Answer

The length of the cell body diagonal is:$$d = \sqrt{a^2 + a^2 + a^2} = \sqrt{3}a$$where a is the unit cell edge length.The atomic radius is half the length of the body diagonal:$$r = \frac{d}{2} = \frac{\sqrt{3}a}{2}$$Substituting the given value of a, we get:$$r = \frac{\sqrt{3} 	imes 426.3 	ext{ pm}}{2} = 184.6 	ext{ pm}$$

Question 4

Gold crystallizes in a face-centered cubic lattice. How many unit cells are there in a gold sample whose mass is 1.50 grams? The atomic weight of gold is 196.97 g mol^-1.Hint: Use dimensional analysis and the number of atoms per unit cell.

Accepted Answer

The correct answer is A.Explanation:The number of unit cells in a sample can be calculated using the following formula:Number of unit cells = (Mass of sample / Molar mass of gold) * (Number of atoms per unit cell / Volume of unit cell)The molar mass of gold is 196.97 g mol-1, and the number of atoms per unit cell in a face-centered cubic lattice is 4. The volume of a unit cell can be calculated using the following formula:Volume of unit cell = (a^3) / 4where a is the length of the side of the unit cell.The length of the side of the unit cell can be calculated using the following formula:a = 2rwhere r is the radius of the gold atom.The radius of the gold atom is 0.144 nm.Substituting these values into the formula for the number of unit cells, we get:Number of unit cells = (1.50 g / 196.97 g mol-1) * (4 / (2 * 0.144 nm)^3) = 1.15 × 10^21 unit cellsTherefore, the correct answer is A.

Question 5

Iron crystallizes in a body-centered cubic lattice. How many unit cells are in an iron sample whose mass is 1.50 grams? The molar mass of iron is 55.85 g mol^-1.Hint: Use dimensional analysis and the number of atoms per unit cell.

Accepted Answer

The answer of Iron crystallizes in a body-centered cubic lattice....

Question 6

What is the mass of a sample of iron that has 5.00 × 10²² unit cells, if the iron crystallizes in a body-centered cubic lattice? The molar mass of iron is 55.85 g mol^-1.Hint: Use dimensional analysis and the number of atoms per unit cell.

Accepted Answer

In a body-centered cubic lattice, there are 2 atoms per unit cell. First, calculate the number of moles of iron atoms: (5.00 × 10^22 unit cells) × (2 atoms/unit cell) × (1 mol/6.022 × 10^23 atoms) = 0.166 mol. Then, calculate the mass: 0.166 mol × 55.85 g/mol = 9.27 g.

Question 7

What is the mass of a sample of silver that has 5.00 × 10²² unit cells, if the silver crystallizes in a face-centered cubic lattice? The molar mass of silver is 107.87 g mol^-1Hint: Use dimensional analysis and the number of atoms per unit cell.

Accepted Answer

A face-centered cubic lattice has 4 atoms per unit cell. Using Avogadro's number, calculate the moles of silver and then multiply by the molar mass to find the mass.

Question 8

Which set of properties below best describes solid ionic crystalline substances?

Accepted Answer

Solid ionic crystalline substances typically have high melting points due to strong ionic bonds, are brittle because of the rigid lattice structure, and are nonconductors in solid form but can conduct electricity when melted or dissolved in water.

Question 9

Which set of properties below best describes metallic substances?

Accepted Answer

Metallic substances typically have a broad range of melting points, can be soft or hard, and are good conductors of electricity in both liquid and solid states due to the presence of free-moving electrons.

Question 10

Which set of properties below best describes molecular crystalline substances?

Accepted Answer

Molecular crystalline substances typically have low melting points, are soft, and are nonconductors due to the weak intermolecular forces holding the molecules together.

Question 11

Paradichlorobenzene is a white crystalline solid which is very soft, has a low melting point, and does not conduct electricity. Which category of substance does it most likely fit under?

Accepted Answer

Paradichlorobenzene is a molecular compound, as it is composed of discrete molecules held together by weak intermolecular forces, explaining its low melting point and lack of electrical conductivity.

Question 12

1,3,6,8-Tetramethylnaphthlene is a white crystalline solid which is very soft, has a low melting point, and is a nonconductor of electricity. Which category of substance does it most likely fit under?

Accepted Answer

1,3,6,8-Tetramethylnaphthalene is a molecular compound, as indicated by its low melting point, softness, and non-conductivity, which are typical properties of molecular substances.

Question 13

Which one of the following substances is most likely composed of ions rather than distinct formula units, when it is in the solid state?

Accepted Answer

The answer of Which one of the following substances is...

Question 14

Which one of the following substances is most likely composed of ions rather than distinct formula units, when it is in the solid state?

Accepted Answer

Calcium chloride (CaCl₂) is an ionic compound, as indicated by its high melting point, which is typical for ionic substances. The other compounds listed have much lower melting points, suggesting they are molecular rather than ionic.

Question 15

A particular solid, crystalline substance has a high melting point and is very hard. It is a non-conductor of electricity, even in the molten state. Most likely, what type of solid is this substance?

Accepted Answer

A covalent crystal is characterized by a high melting point, hardness, and non-conductivity of electricity, even when molten, due to the strong covalent bonds throughout the crystal lattice.

Question 16

Silicon carbide, which has the empirical formula SiC, melts at 2830°C and is nearly as hard as diamond. Which category of substance does silicon carbide most likely fit into?

Accepted Answer

Silicon carbide is a covalent network solid, similar to diamond, with strong covalent bonds throughout the structure, leading to its high melting point and hardness.

Question 17

Boron nitride has the empirical formula BN, melts at 2967°C and is nearly as hard as diamond. Which category of substance does boron nitride most likely fit into?

Accepted Answer

Boron nitride is a covalent network solid, similar to diamond, with strong covalent bonds throughout the structure, contributing to its high melting point and hardness.

Question 18

An unknown solid is soft and lustrous. It has a low melting point and conducts electricity well as a solid or liquid. What kind of crystal best describes this solid?

Accepted Answer

Metallic crystals are typically lustrous, have a range of melting points, and conduct electricity well in both solid and liquid states due to the presence of delocalized electrons.

Question 19

An unknown solid is soft and brittle with a low melting point. It does not conduct electricity in either the solid or liquid phase. What kind of crystal best describes this solid?

Accepted Answer

Molecular crystals are typically soft and brittle, have low melting points, and do not conduct electricity in either solid or liquid phases, which matches the description given.

Question 20

An unknown solid is hard and brittle with a high melting point. It does not conduct electricity as a solid, but does as a liquid. What kind of crystal best describes this solid?

Accepted Answer

Ionic crystals are typically hard and brittle with high melting points. They do not conduct electricity in solid form but do conduct when melted or dissolved in water, as the ions are free to move.

Quiz 12: Intermolecular Attractions and the Properties of Liquids and Solids

Gold crystallizes in a face-centered cubic lattice. How many unit cells are there in a gold sample whose mass is 1.50 grams? The atomic weight of gold is 196.97 g mol-1.Hint: Use dimensional analysis and the number of atoms per unit cell.

Iron crystallizes in a body-centered cubic lattice. How many unit cells are in an iron sample whose mass is 1.50 grams? The molar mass of iron is 55.85 g mol-1.Hint: Use dimensional analysis and the number of atoms per unit cell.

What is the mass of a sample of iron that has 5.00 × 1022 unit cells, if the iron crystallizes in a body-centered cubic lattice? The molar mass of iron is 55.85 g mol-1.Hint: Use dimensional analysis and the number of atoms per unit cell.

What is the mass of a sample of silver that has 5.00 × 1022 unit cells, if the silver crystallizes in a face-centered cubic lattice? The molar mass of silver is 107.87 g mol-1Hint: Use dimensional analysis and the number of atoms per unit cell.

Which set of properties below best describes solid ionic crystalline substances?

Which set of properties below best describes metallic substances?

Which set of properties below best describes molecular crystalline substances?

Paradichlorobenzene is a white crystalline solid which is very soft, has a low melting point, and does not conduct electricity. Which category of substance does it most likely fit under?

1,3,6,8-Tetramethylnaphthlene is a white crystalline solid which is very soft, has a low melting point, and is a nonconductor of electricity. Which category of substance does it most likely fit under?

Which one of the following substances is most likely composed of ions rather than distinct formula units, when it is in the solid state?

Which one of the following substances is most likely composed of ions rather than distinct formula units, when it is in the solid state?

A particular solid, crystalline substance has a high melting point and is very hard. It is a non-conductor of electricity, even in the molten state. Most likely, what type of solid is this substance?

Silicon carbide, which has the empirical formula SiC, melts at 2830°C and is nearly as hard as diamond. Which category of substance does silicon carbide most likely fit into?

Boron nitride has the empirical formula BN, melts at 2967°C and is nearly as hard as diamond. Which category of substance does boron nitride most likely fit into?

An unknown solid is soft and lustrous. It has a low melting point and conducts electricity well as a solid or liquid. What kind of crystal best describes this solid?

An unknown solid is soft and brittle with a low melting point. It does not conduct electricity in either the solid or liquid phase. What kind of crystal best describes this solid?

An unknown solid is hard and brittle with a high melting point. It does not conduct electricity as a solid, but does as a liquid. What kind of crystal best describes this solid?

Gold crystallizes in a face-centered cubic lattice. How many unit cells are there in a gold sample whose mass is 1.50 grams? The atomic weight of gold is 196.97 g mol^-1.Hint: Use dimensional analysis and the number of atoms per unit cell.

Iron crystallizes in a body-centered cubic lattice. How many unit cells are in an iron sample whose mass is 1.50 grams? The molar mass of iron is 55.85 g mol^-1.Hint: Use dimensional analysis and the number of atoms per unit cell.

What is the mass of a sample of iron that has 5.00 × 10²² unit cells, if the iron crystallizes in a body-centered cubic lattice? The molar mass of iron is 55.85 g mol^-1.Hint: Use dimensional analysis and the number of atoms per unit cell.

What is the mass of a sample of silver that has 5.00 × 10²² unit cells, if the silver crystallizes in a face-centered cubic lattice? The molar mass of silver is 107.87 g mol^-1Hint: Use dimensional analysis and the number of atoms per unit cell.