A student is given four solid samples labeled W, X, Y, and Z. All have a metallic luster. She is told that the solids could be gold, lead sulfide, mica ( which is quartz, or SiO 2 ) , and iodine. The results of her investigations are: (a) W is a good electrical conductor; X, Y, and Z are poor electrical conductors. (b) When the solids are hit with a hammer. W flattens out. X shatters into many pieces. Y is smashed into a powder, and Z is not affected. (c) When the solids are heated with a Bunsen burner. Y melts with some sublimation, but X, W, and Z do not melt. (d) In treatment with 6 M HNO 3 , X dissolves; there is no effect on W, Y, or Z. On the basis of these test results, identify the solids.
A student is given four solid samples labeled W, X, Y, and Z. All have a metallic luster. She is told that the solids could be gold, lead sulfide, mica ( which is quartz, or SiO 2 ) , and iodine. The results of her investigations are: (a) W is a good electrical conductor; X, Y, and Z are poor electrical conductors. (b) When the solids are hit with a hammer. W flattens out. X shatters into many pieces. Y is smashed into a powder, and Z is not affected. (c) When the solids are heated with a Bunsen burner. Y melts with some sublimation, but X, W, and Z do not melt. (d) In treatment with 6 M HNO 3 , X dissolves; there is no effect on W, Y, or Z. On the basis of these test results, identify the solids.
Solution Summary: The author explains that ionic crystals are made up of ions that are bonded by the electrostaticforce of attraction.
A student is given four solid samples labeled W, X, Y, and Z. All have a metallic luster. She is told that the solids could be gold, lead sulfide, mica
(
which is quartz, or SiO
2
)
,
and iodine. The results of her investigations are: (a) W is a good electrical conductor; X, Y, and Z are poor electrical conductors. (b) When the solids are hit with a hammer. W flattens out. X shatters into many pieces. Y is smashed into a powder, and Z is not affected. (c) When the solids are heated with a Bunsen burner. Y melts with some sublimation, but X, W, and Z do not melt. (d) In treatment with 6 M
HNO
3
,
X dissolves; there is no effect on W, Y, or Z. On the basis of these test results, identify the solids.
A cubic unit cell contains manganese ions at the corners and fluoride ions at the center of each edge.(a) What is the empirical formula of this compound? Explain your answer.(b) What is the coordination number of the Mn3+ ion?(c) Calculate the edge length of the unit cell if the radius of a Mn3+ ion is 0.65 A.(d) Calculate the density of the compound.
A student is given four solid samples labeled W, X, Y, and Z. All have a metallic luster. She is told that the solids could be gold, lead sulfide (PbS), quartz which is SiO2,
and iodine. The results of her investigations are: (a) W is a good electrical conductor; X, Y, and Z are poor electrical conductors. (b) When the solids are hit with a hammer, W flattens out, X shatters into many pieces, Y is smashed into a powder, and Z is not affected. (c) When the solids are heated with a Bunsen burner, Y melts with some sublimation, but X, W, and Z do not melt. (d) In treatment with 6 M HNO3, X dissolves; there is no effect on W, Y, or Z. On the basis of these test results, which samples are; Au, PbS, SiO2, and I2
(b) Using the Crystallographer's
formula to determine the density (in g/cm³) of Po:
ρ = Σ Ζ * Μ
Vell* N
You must know that a primitive cubic cell has Z = 1
Since Po is a metal, the value of "i" = 1, since it's the only entity!
MM of Po= 208.998 g/mol
Vcell (in cm³) = a³
Vcell (3.36 x 10-8 cm)³ = 3.793 x 10-23 cm³
N = 6.022 x 1023 atoms/mol
Thus: p = (1 atom/cell) (208.998 g/mol) = 9.16 g/cm³
(3.793 x 10-23 cm³) (6.022 x 1023)
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Unit Cell Chemistry Simple Cubic, Body Centered Cubic, Face Centered Cubic Crystal Lattice Structu; Author: The Organic Chemistry Tutor;https://www.youtube.com/watch?v=HCWwRh5CXYU;License: Standard YouTube License, CC-BY