A few questions about weak bases and crystal structures

Weak bases: ammonia, triethylamine, ethylenediamine, etc. are covalent compounds; Cu(OH)2 and Fe(OH)3 are ionic compounds.

A weak base is an electrolyte, and since it is called a "weak" base, of course it is a weak electrolyte.

The molten state of the weak base of the molecule does not conduct electricity, and the aqueous solution conducts electricity. Weak bases such as Cu(OH)2 and Fe(OH)3 do not have a molten state and decompose as soon as they are heated.

About your opinion:

1. The molten state of liquid crystal can also conduct electricity, and liquid crystal is not an ionic compound.

2. For some extremely insoluble ionic compounds such as Cus, the conductivity of aqueous solution is the same as that of water; Sucrose and glucose are covalent compounds, and aqueous solutions have the same electrical conductivity as water.

3. The aqueous solution of AlCl3 conducts electricity, but it is not AlCl3 that conducts electricity, but HCl produced by hydrolysis.

The study of chemistry is afraid of absolutes.

Weak bases, such as Cu(OH)2, Fe(OH)3, etc., are ionic compounds composed of ions.

A weak base is an electrolyte and is a weak electrolyte.

1.No, for example, Cu can conduct electricity in the molten state, but it is not an ionic compound 2No, ionic compounds do not necessarily conduct electricity in the molten state or in aqueous solutions because some ionic compounds are hydrolyzed or thermally decomposed.

3.Yes, AlCl3 is a covalent compound, it is difficult to conduct electricity when melted, and it conducts electricity in aqueous solutions.

A: Does it depend on the form of the molecule? I guess what you don't understand is the latter in the middle of a, the heavy rain in the former!

In fact, the molecules of the two are different.

BCA dry ice and solid carbon disulfide are both molecular crystals, molecular crystals with similar composition and structure, and the intermolecular force depends on the relative molecular weight, the larger the relative molecular mass, the greater the intermolecular force, the higher the crystal boiling point, CO2KCl

c.Diamond and crystalline silicon are both atomic crystals, and the boiling point depends on the size of the covalent bond, the smaller the atomic radius, the stronger the covalent bond between the atoms, and the higher the boiling point.

Diamond crystalline silicon.

d.Dry ice and carbon dioxide crystals? It's the same.

A higher boiling point is more stable, and atomic crystals are more stable than molecular crystals!

A dry ice is CO2, CS2 are molecular crystals, see who has a large molecular weight is stable! SC2 High I do not choose it.

B Same as above, KaCl high boiling point is not selected.

c diamond is c silicon is si small atomic radius is more stable, so c stable choose c

d two are the same.

The stronger the covalent bond between the atoms, the higher the boiling point.

The stronger the ionic bond energy, the higher the boiling point.

The greater the relative molecular mass, the stronger the intermolecular forces, and the higher the boiling point, through these three you can judge that the correct answer is BC

1. The Braffy lattice does not include a close-row hexagonal lattice. Because the close-packed hexagonal lattice can be disassembled into a body-centered orthogonal lattice.

2. The face-centered quadrangular lattice can be disassembled into simple orthogonal.

The rest of the questions are not difficult in themselves, but they need to be drawn to solve them, which is more tedious, so let's do your own research.

5. Agree with the statement of the fourth floor.

8. No errors. The crystal structure of hexagonal ZNS is actually wurtzite structure, and if positive and negative ions are not distinguished, then positive ions actually occupy 1 2 tetrahedral gaps. If distinguished, one lattice is displaced by one-third of the lattice vector along the c-axis relative to the other.

Because the general wurtzite structure is only the most local structure, if lz draws more points, it will naturally be seen.

1. The Braffy lattice does not include a close-row hexagonal lattice. Because the close-packed hexagonal lattice is not the simplest, it can be broken down into other simple lattices.

2. The face-centered quadrangular lattice can be decomposed into a simple orthogonal lattice.

3. How to draw the crystal orientation of a known exponent? What are some tips? Illustrate.

Select an origin o in the unit cell, conform to the right-hand rule, and walk according to the requirements. For example, (-102), first simplify the maximum exponent to 1, that is, reduce it to (-1 2 0 1), and then start from the origin, go one square in the negative direction of the x-axis, 0 squares in the y direction, and 1 square in the z direction to get the point a. Attaching OA yields a crystal orientation (-102).

4.How do I draw a crystal plane with a known exponent? What are some tips? Illustrate.

For crystal planes that are similar to crystal directions, take the reciprocal first, and then find the intercept along the triaxial direction and connect it.

5.For hexagonal crystal systems, what are the methods and techniques when drawing the crystal orientation and crystal plane of a known exponent?

Hexagonal crystal system, pay attention to the transformation of three-axis coordinates and four-axis coordinates! If the hexagonal crystal system gives the chamber triaxial coordinates, first convert the triaxial coordinates into quadruple coordinates! It's easy to draw again!

TiO2 is a relatively complex crystal structure, the crystal lattice is cuboidal, Ti atoms are at eight vertices and body center, four O are on the surface, two O are in the middle, and oxygen atoms form an octahedral structure.

A unit cell can be thought of as being composed of lattice points plus structural primitives (structural units). Lattice points are points that are abstracted from the unit cell structure, and structural units are what these points represent. Therefore, of course, there is no need to calculate commons when analyzing structural units.

Hope it helps you understand.

Stacking multiple structural units together, you can know that the atom or molecule at the top angle accounts for 1 8, that is, the 8 unit cell units share which atom or molecule, the face center accounts for 1 2, and the prism accounts for 1 4, understand?

Question 1:

No matter what the substance.

As long as it is an aqueous solution.

That's all a mixture.

HCl is an electrolyte and hydrochloric acid is not an electrolyte.

Electrolyte concept: ammonia NH3, a compound that can conduct electricity in an aqueous solution or in a molten state, is dissolved in water to form ammonia monohydrate NH3·H2O, which is not ammonia itself, so ammonia cannot be called an electrolyte, but can only be called a non-electrolyte. But ammonia is not an electrolyte because it is a mixture.

Question 2: It is necessary to memorize the top 20 commonly used places.

From the ratio of the C and A axes of the Ti hexagonal crystal, it can be seen that in fact, Ti is not an ideal hexagonal crystal system. ideal c a=,mg=; ti=, indicating that the ti layer and the interlayer are very dense, so it may lead to an increase in the slip system and a better plasticity.

1.After the saturated solution washes out the crystals, what is obtained must be a saturated solution, otherwise the crystals will not be absorbed, but the solubility of this saturated solution is different from the previous one, because the temperature is different.

2.Just now ... Definitely, yes.

3.No, this is related to the solubility properties, such as Kno3, the solubility decreases with the decrease of temperature: but think of Ca(OH)2, as the temperature decreases, the solubility increases, so it does not wash out the crystals.

4.There are many ways to crystallize, however, there are two kinds: one is the saturated solution you said, which will crystallize after a certain period of time, and the other is called supersaturated solution, that is, the dissolved solute exceeds the solubility of this temperature, and it will crystallize.

Why some saturated solutions are still saturated solutions after precipitating crystals, while some saturated solutions are unsaturated solutions after precipitating crystals.

That doesn't seem right. Under the condition that the external conditions do not change, the solution after precipitation and crystallization is saturated, and if it is not saturated, the crystals in it will be re-dissolved, so that the solution is saturated. Unless the crystallization is filtered out after precipitation, and then the external environment is changed, the solution after precipitation crystallization must be saturated.

This experiment is not in the book of the People's Education Edition, and it seems that the book of the Shandong Science and Technology Edition is in the elective 3 Material Structure and Properties.

1.Experimental principle.

Copper sulfate crystal is a relatively stable crystalline hydrate, when heated to about 150, it will lose all the crystal water, according to the quality difference before and after heating, the crystal water content of the crystal can be calculated.

2.Experimental instruments.

Tray balances, mortars, glass rods, tripods, mud triangles, porcelain crucibles, crucible pliers, dryers, alcohol lamps, medicine spoons.

3.Procedure.

1) Grinding: Grind the copper sulfate crystals in a mortar. (Prevents splashing during heating).

2) Weighing: Accurately weigh the mass of a dry and clean porcelain crucible (wg).

3) Re-weighing: Weigh the mass of porcelain crucible + copper sulfate crystal (W1G).

4) Heating: Slowly heat over low heat until all the blue crystals turn into white powder (complete loss of water), and put it in a dryer to cool.

5) Re-weighing: After cooling in the dryer (because copper sulfate has strong hygroscopicity), weigh the mass of porcelain crucible + copper sulfate powder (W2G).

6) Reheating: Reheat the porcelain crucible containing copper sulfate and then cool it.

7) Re-weighing: The cooled porcelain crucible containing copper sulfate is weighed again (two weighing errors, the tray balance can not identify the following mass).

8) Calculation: Calculate the mass fraction of crystalline water in copper sulfate crystals according to the results measured by experiments.

Abbreviations: "one grind", "four names", "two heats", "one calculation".

Wouldn't you? Select C