Chemistry problems to solve, solve, chemistry problems

The sodium hydroxide reacts with carbon dioxide, the pressure in the bottle decreases, and the balloon becomes larger.

2) I don't know what it means, since the balloon hasn't changed, I don't know what it did.

Hydrochloric acid reacts with sodium carbonate to produce carbon dioxide and the pressure in the bottle becomes greater and flattens the balloon.

Ca(OH)2 + CO2 ==== CaCO3 + H2O carbon dioxide can react with sodium hydroxide.

1) The sodium hydroxide and the carbon dioxide in the bottle undergo a metathesis reaction, the carbon dioxide is consumed, the pressure in the bottle is less than the atmospheric pressure (that is, the pressure in the balloon), and the balloon is inflated.

2) Operation: Continue to pump the sodium hydroxide solution into the bottle until the balloon stops inflating;

Purpose: To consume all the CO2 from the original bottle, so as to ensure that the CO2 verified by subsequent experiments is produced by the subsequent operation3 and not the original one.

3)ca(oh)2 + co2= caco3 + h2o

4) Conclusion: Because carbon dioxide can react with sodium hydroxide.

Do I need to do question 9?

Take a small amount of the sample and add excess calcium chloride solution until the white precipitate no longer increases. (Because sodium hydroxide deterioration is most likely due to the formation of carbonate ions by reacting with carbon dioxide in the air.) cacl2+na2co3=caco3+2nacl)

Filter the mixture in 1, take the filtrate, and drop it into the phenolphthalein solution, if it is not completely deteriorated, the solution should appear red. Otherwise it should be colorless.

（1）h o na s

2) Polar covalent bonds.

3) Ionic polar covalently bonded ions.

Their atomic numbers increase sequentially, and the sum of the proton numbers of the atoms of the Y and Z elements is three times the sum of the protons of the Y and X atoms.

From this, it can be seen that the outermost electron numbers of y and w are equal (same family!). ）。Only y is a metallic element---al w --b

or y---na w---h

The sum of the proton numbers of the atoms of the Y and Z elements is three times the sum of the protons of the O and X atoms.

The sum of the protons of the atoms of y and z is less than 18+18 (short period).

The sum of the number of protons is less than 36 by 3 times, and the sum of the number of protons of the two denions of w and x is less than 12

W should be Hy---na

The covalent molecule of W2Z ---z is S

then x---11+16) 3-1=8 is o

1) Write the element symbol: w is h, x is o y, na z is s 2) w2z is a covalent molecule composed of polar covalent bonds, and its formation process is represented by electronic formula

The formation process of H2S is omitted.

3) There are ionic compounds composed of covalent and ionic bonds in substances composed of y, x, and w.

0=5 Now start looking, let w = boron, y = aluminum, 13 + z = 3 (5 + x), z = 3x + 2> 17 no solution.

Therefore w = hydrogen, then y = sodium, 11 + z = 3 (1 + x), z + 8 = 3x, and z = (silicon, phosphorus, sulfur and chlorine) 14 17, so z = sulfur 16

Therefore, (1) w=h, x=o, y=na, z=s(2) covalent bonds, electronically cannot be drawn (2h.).+:o..:=h:o...h）

3) NaOH, ionic bonds, covalent bonds, ionic compounds.

（1）h o na s

2) Polar covalent bond (polar bond) 2h·+ s· h:s:h.

3) Polar Bond Ionic Bond Ion.

1, w, x, y, and z are h, o, na, s, respectively

2, W2Z is sulfur dioxide, which is a covalent molecule composed of S-O bonds.

3. Sodium hydroxide contains Na-O bonds and O-H bonds.

(2) The colorless gas is CO2, and there are three substances in the colorless solution B: Ca(NO3)2, HNO3, and NaNO3;

3) The chemical equation for the formation of white solid B during the experiment is: BA(NO3)2+Na2SO4=BASO4 +2nano3;

4) There is a substance that may exist in the original white solid, to determine whether it exists, add a colorless phenolphthalein solution A dropwise, if the colorless phenolphthalein solution turns red after dropping, the substance must exist (the substance is NaOH).

Analysis: The inference problem is generally a breakthrough from the last phenomenon, the breakthrough of this question is the addition of excessive nitric acid and the existence of precipitation, the introduction of the precipitate is barium sulfate, and there must be barium nitrate and sodium sulfate in the solution; If nitric acid is added to gas, there must be calcium carbonate. Sodium hydroxide may be present.

(2) CO2,3 (calcium chloride, sodium nitrate, nitric acid).

3）ba（no3）+na 2so4==baso4！+2na no3

4) Phenolphthalein, if reddened.

1. A kind of particle that maintains the chemical properties of a substance.

3. The nucleus of the proton, with a unit of positive charge, the electron outside the nucleus, with a unit of negative charge.

4. The number of nuclear charges, the number of protons, and the number of electrons outside the nucleus.

Which question specifically, all of them?

It's simple.

2hcl+ca(oh)2=cacl2+2h2oh2so4+ca(oh)2=caso4+2h2ohcl+koh=kcl+h2o

h2so4+2koh=k2so4+2h2o3hcl+al(oh)3=alcl3+3h2o2hcl+mg(oh)2=mgcl2+2h2o2hcl+cu(oh)2=cucl2+2h2oh2so4+cu(oh)2=cuso4+2h2o3hcl+fe(oh)3=fecl3+3h2o3h2so4+2fe(oh)3=fe2(so4)3+6h2o Some numbers are the lower corner mark, pay attention.

b water d number of protons and neutrons.

d electron a nuclear charge number 79

c, bcdb40d6 protons 6 electrons.

neutrons, protons, electrons 22

Aunt Ion, Father-in-law, oh, come and cluck.

Although I can't see this topic very clearly, I don't think this question is too difficult. A substance is carbonate, it is certain that there are copper ions in it, and the key is to grasp a classification of salts: normal salts, acid salts, and basic salts.

There is not much description of the positive carbonate of copper in the textbook, but there is a chemical equation for the thermal decomposition of basic copper carbonate, and the results are copper oxide, carbon dioxide, and water. Therefore, Shunyi can react these three substances with hydrochloric acid, and the result is copper chloride, water and carbon dioxide, which you can solve later.