Chemistry foundation questions in high school, several chemistry foundation questions in high school

That's right.

Chloride ions refer to chlorine that can be ionized, and negative 1 valent chlorine is ionized, for example, there is negative 1 valent chlorine ionized by water in hydrochloric acid solution.

The other valence states of chlorine are atomic clusters formed by being together with other atoms, such as: hypochlorous acid and clo- chloric acid with clo3 2- and perchloric acid with clo4 + These three acid groups are atomic clusters, and the chlorine in them cannot be ionized, in other words, it cannot exist alone.

So only chlorine, which is reduced to minus 1 valence, can be ionized, i.e., only it is an ion, and then it must have one more electron than the chlorine atom.

The Cl ion is said to have 8 electrons outside the nucleus, that is, one more electron than the Cl atom.

As for the valency of Cl, it is manifested when Cl and other atoms form an atomic cluster, such as Clo

The outermost shell of the chlorine atom has seven electrons, and when one electron is added, it becomes the chloride ion Cl-, and when the chlorine atom becomes Cl+, it does not lose electrons, but forms a shared electron pair with the electrons in other atoms (such as hydrogen). The electron pair is biased towards hydrogen, so the chloride ion at this point still has one more electron than the chlorine atom. By analogy, this sentence is correct.

The chloride ion is cl-, so there is one more electron than the chlorine atom, don't think too much.

Other valences are represented in atomic clusters.

1、caco3

2. The density is less than that of water, insoluble in water and does not react with water.

3. Objects with low density will float on top of the rocky slide with high density.

4. Cl2 may volatilize from water after being dissolved in water, and one liter of water can only dissolve two liters of chlorine gas.

5. Saturated salt water should be used for washing, according to the ionic effect, Cl- is saturated in the water, and will not react with Cl2.

1 marble caco3

2. The density of the drainage method does not matter, there is no gas density greater than water in the impression, the gas should not be soluble or insoluble water, and it cannot be reversed with water.

3. A balloon will float up if it is placed in the water... What about turning the sink upside down? (The metaphor is not appropriate, you need to understand it yourself).

4 Because Cl2 seems to be dissolved, it will volatilize again... Or decompose after the reaction...

5. Understand the purpose. This question is mainly about how to remove impurities, that is, how to remove HCL gas, HCL is very soluble in water, the volume ratio is 1:500 to dissolve, NaCl is another anti-early response, besides, Cl2 and water do not seem to react much...

It's just a matter of dissolving, dissolving ... Forgot about solubility... The main thing is to say ...

The test for you is to remove miscellaneous problems... Don't pay too much attention to the rest.

When writing ionic equations, you need to pay attention to writing precipitates, gases, insoluble objects such as AGCL, BaCO3, H2, etc., and of course, H2O. And soluble substances cannot be written.

In the generation of these substances, some basic ionic equations can be determined, oh—+h+=h2o

Na+ is soluble, so it is impossible to write out, all Na salts are soluble.

Therefore, when you first write, you can write the chemical equation first, and then break it down into the ion equation.

Write one for you.

BaCO3 + 2Hno3 = Ba(NO3)2 + H2 (gas symbol) Because BaCO3 is insoluble, it is written out, the essence of this reaction H+ participates in the reaction (generates H2), and because barium nitrate is soluble, so nitrate ions do not need to be written, as long as hydrogen ions are written.

Ion equation writing steps: 1, write 2, split 3, delete (delete duplicate ions) 4, check (conservation of mass, conservation of charge).

Detachable substance: 1: strong acid: H2SO4 (concentrated H2SO4 is not detachable) HNO3 HCl HBR HI HCO4

2: Strong alkali: KOH Ca(OH)2 (lime milk is not detachable) Naoh BA(OH)2

3: Soluble salts (strong acidic acid salts such as NaHSO4: in water: NAHSO4==NA+ +H+ +SO4 2- in the molten state: NAHSO4==NA+ +HSO4 -

Weak and strong acid acid salts: such as: NaHCO3==Na+ +HCO3 - do not study melting, because it is easy to decompose when heated).

Barium carbonate is insoluble and cannot be removed.

NaOH+HCl==NACl+H2O gives NA+ +OH- +H+ +Cl- =NA+ +Cl- +H2O gives OH- +H+==H2O

Quite simply, when writing the ionic equation, substances that are easily soluble in water and easily ionized are represented by ion symbols (and symbols for the electrical products of the substance), while substances that are insoluble in water, volatile substances and water are still represented by chemistry.

EG hydrochloric acid and sodium hydroxide.

hcl+naoh===nacl+h2o

H+ Cl- Na+ Oh-===H2O +Na+ Cl- The ion equation of the reaction can be obtained by deleting the symbol of the ions that do not change before and after the reaction (essentially not participating in the reaction) in the above equation.

h+ oh-==h2o

First of all, the one that can be disassembled into ionic form is disassembled into ionic form, and the precipitation, gas, and water can not be disassembled will be kept as it is, mainly depending on which element has changed in valency. In the neutralization reaction you are talking about, hydrogen ions and hydroxide ions are neutralized to form water, and water cannot be disassembled. There are also reactions between salts and alkalis or acids to see if the products have precipitation or gases.

To put it simply, it is to look at the ions before the reflection. After the reaction became intolerable. Slightly soluble.

Water.. Gas. That is, the conditions of the products produced in the metathesis reaction.

If yes, I participated in the reaction... Calcium carbonate is encountered in the reactants. When barium and other things are not allowed.

It needs to be written in full. Sodium carbonate is soluble. So you don't have to write it all...

Because sodium hydroxide and hydrochloric acid occur as a neutralization reaction. It's just that H and OH ions react to form water. (The same reasoning).

Barium carbonate is solid, so it is not dismantled in the reaction. When an ion does not bind to other ions as insoluble substances, microsoluble substances, water, gases, or weak electrolytes after the reaction, the ions do not really participate in the reaction. In the reaction of sodium carbonate and sulfuric acid, the above substances are not produced after the reaction of sodium ions and chloride ions, and they still exist in the form of their own ions in the solution, so they do not participate in the reaction.