Colorless bright red. USE assignments in chemistry with solutions: The relationship of various classes of inorganic substances Determination of mineral fertilizers

1. A solution of substance Y was added to a test tube with a solution of salt X. As a result, a reaction occurred, which is described by the following abbreviated ionic equation S 2- + 2H + = H 2 S. From the proposed list, select substances X and Y that can enter into the described reaction.

1) sodium sulfide;

2) carbonic acid;

3) hydrogen chloride;

4) iron (II) sulfide;

5) potassium sulfite;

1. A solution of substance Y was added to a test tube with a solution of salt X. As a result of the reaction, a white precipitate was observed,

1) potassium nitrate;

2) barium chloride;

H) hydrochloric acid;

4) calcium carbonate;

5) sulfuric acid;

Write in the table the numbers of the selected substances under the corresponding letters.

1. A solution of substance Y was added to a test tube with a solution of sodium salt X. As a result, a reaction occurred, which is described by the following abbreviated ionic equation:

S 2- + Fe 2+ \u003d FeS.

From the proposed list, select substances X and Y that can enter into the described reaction.

1) sodium sulfide;

2) sodium sulfite;

3) hydrogen sulfide;

4) iron (II) hydroxide;

5) iron sulfate (II);

Write in the table the numbers of the selected substances under the corresponding letters.

1. A solution of substance Y was added to a test tube with a solution of salt X. As a result of the reaction, evolution of a colorless gas was observed. From the proposed list, select substances X and Y that can enter into the described reaction.

1) potassium sulfite;

2) sodium hydroxide;

H) iron(II) sulfate;

4) hydrogen chloride;

5) sodium nitrate.

Write in the table the numbers of the selected substances under the corresponding letters.

1. A solution of acid Y was added to a test tube with a solution of substance X. As a result, a reaction occurred, which is described by the following abbreviated ionic equation: OH - + H + = H 2 O.

From the proposed list, select substances X and Y that can enter into the described reaction.

1) sodium sulfide;

2) carbonic acid;

3) sulfuric acid;

4) barium hydroxide;

5) potassium hydroxide.

Write in the table the numbers of the selected substances under the corresponding letters.

1. A solution of salt Y was added to a test tube with a solution of substance X. As a result of the reaction, a blue precipitate was observed. From the proposed list, select substances X and Y that can enter into the described reaction.

1) iron(II) sulfate;

2) hydrochloric acid;

3) sodium hydroxide;

4) calcium nitrate;

5) copper (II) sulfate.

Write in the table the numbers of the selected substances under the corresponding letters.

1. A solution of substance Y was added to a test tube with a solid, water-insoluble substance X. As a result of the reaction, the dissolution of the solid substance was observed without gas evolution. From the proposed list, select substances X and Y that can enter into the described reaction.

1) calcium carbonate;

2) sodium hydroxide;

H) barium sulfate;

4) sulfuric acid;

5) copper(II) oxide.

Write in the table the numbers of the selected substances under the corresponding letters.

1. A solution of salt Y was added to a test tube with a solution of substance X. As a result, a reaction occurred, which is described by the following abbreviated ionic equation: CO 3 2- + 2H + \u003d H 2 O + CO 2.

From the proposed list, select substances X and Y. that can enter into the described reaction.

1) calcium bicarbonate;

2) calcium hydroxide;

3) acetic acid;

4) sulfuric acid;

5) sodium carbonate.

Write in the table the numbers of the selected substances under the corresponding letters.

1. A solution of salt Y was added to a test tube with a solution of substance X. As a result of the reaction, a brown precipitate was observed. From the proposed list, select substances X and Y that can enter into the described reaction.

1) copper(II) chloride;

2) hydrochloric acid;

3) sodium hydroxide;

4) sodium nitrate;

5) iron(III) sulfate.

Write in the table the numbers of the selected substances under the corresponding letters.

1. A solution of substance Y was added to a test tube with an acid X solution. As a result, a reaction occurred, which is described by the following abbreviated ionic equation: SO 3 2- + 2H + \u003d H 2 O + SO 2.

From the proposed list, select substances X and Y that can enter into the described reaction.

1) potassium sulfate;

2) hydrosulphuric acid;

3) sulfuric acid;

4) ammonium sulfide;

5) sodium sulfite.

Write in the table the numbers of the selected substances under the corresponding letters.

1. Zinc was completely dissolved in a concentrated sodium hydroxide solution. The resulting clear solution of substance X was evaporated and then calcined. This formed a solid substance Y. From the proposed list, select substances X and Y that correspond to the description given.

1) Na 2 ZnO 2;

2) Zn(OH) 2 ;

3) ZnO;

4) Na 2;

5) NaOH.

Write in the table the numbers of the selected substances under the corresponding letters.

1. A solution of sodium chloride was mixed with a solution of salt X. The precipitated white precipitate was separated, the solution was evaporated, the remaining dry salt was calcined in air, and a colorless gas Y was released. From the proposed list, select substances X and Y that correspond to the description given.

1) AgNO 3 ;

2) HNO3;

3) Na 2 CO 3;

4) CO 2 ;

5) O2.

Write in the table the numbers of the selected substances under the corresponding letters.

1. Aluminum nitrate was calcined. The resulting solid X was fused with an excess of potassium hydroxide. The resulting melt was treated with an excess of water, and a clear solution of substance Y was formed. From the proposed list, select substances X and Y that correspond to the description given.

1) Al;

2) Al 2 O 3;

3) KAlO 2 ;

4) K;

5) K 3 AlO 3 .

Write in the table the numbers of the selected substances under the corresponding letters.

1. Iron(II) hydroxide was inverted with peroxide. The resulting brown substance X was fused with solid potassium hydroxide. The resulting melt containing salt Y was treated with excess water, as a result of which a brown substance X was again obtained. From the proposed list, select substances X and Y that correspond to the above description.

1) Fe 2 O 3;

2) Fe(OH) 3 ;

3) KFeO 2 ;

4) FeO;

5) K 3 FeO 3;

Write in the table the numbers of the selected substances under the corresponding letters.

1. Aluminum hydroxide was fused with potassium hydroxide. The resulting salt X was treated with an excess of hydrochloric acid, and substance Y was formed. From the proposed list, select substances X and Y that correspond to the description given.

1) K;

2) KAlO 2 ;

3) K 3 AlO 3 ;

4) AlCl 3 ;

5) Al(ClO 4) 3;

Write in the table the numbers of the selected substances under the corresponding letters.

1. Potassium sulfite was treated with hydrochloric acid. The resulting gas X was absorbed by an excess of calcium hydroxide, and substance Y was formed. From the list provided, select substances X and Y that match the description given.

1) H2S;

2) CaS;

3) Ca(HSO 3) 2;

4) SO2;

5) CaSO3.

Write in the table the numbers of the selected substances under the corresponding letters.

1. A strong acid X was added to one of the test tubes with a precipitate of aluminum hydroxide, and a solution of substance Y was added to the other. As a result, the precipitate was observed to dissolve in each of the test tubes. From the proposed list, select substances X and Y that can enter into the described reactions.

1) hydrobromic acid;

2) sodium hydrosulfide;

3) hydrosulfide acid;

4) potassium hydroxide;

5) ammonia hydrate.

Write in the table the numbers of the selected substances under the corresponding letters.

1. Silver nitrate was calcined. Concentrated nitric acid was added to the formed solid residue X, and intensive evolution of gas Y was observed. From the list provided, select substances X and Y that correspond to the description given.

1) silver(I) oxide;

2) silver nitrite;

3) silver;

4) nitric(II) oxide;

5) nitric oxide(IV).

Write in the table the numbers of the selected substances under the corresponding letters.

Silver bromide was heated with zinc powder. The resulting salt was dissolved in water. Potassium hydroxide solution was added dropwise to the resulting solution. First, a white precipitate X occurred, and then, when a new portion of the potassium hydroxide solution was added, it completely dissolved with the formation of substance Y. From the proposed list, select substances X and Y that correspond to the above description.

1) Ag;

2) ZnBr 2 ;

3) Zn(OH) 2 ;

4) K 2 ZnO 2;

5) K2.

Write in the table the numbers of the selected substances under the corresponding letters.

1. Phosphorus(V) chloride was added to an excess of barium hydroxide solution. The resulting precipitate X was separated, dried and calcined with sand and coal, and substance Y was formed. From the proposed list, select substances X and Y that correspond to the description given.

1) Ba 3 (PO 4) 2;

2) BaHPO4;

3) BaCl 2 ;

4) CO 2 ;

5) CO.

Write in the table the numbers of the selected substances under the corresponding letters.

1. Sodium dichromate reacted with sodium hydroxide. The resulting substance X was treated with sulfuric acid, and an orange substance Y was isolated from the resulting solution. From the proposed list, select substances X and Y that match the description given.

1) Na 2 Cr 2 O 7;

2) Na 2 CrO 4;

3) NaCrO 2 ;

4) Na 3;

5) Na 2 SO 4.

Write in the table the numbers of the selected substances under the corresponding letters.

1. Copper(II) sulfate was added to the barium chloride solution. The resulting precipitate X was filtered off. Potassium iodide was added to the remaining solution, and a Y precipitate was observed and the color of the solution changed. From the proposed list, select substances X and Y that match the description given.

1) BaSO3;

2) BaSO4;

3) CuI 2 ;

4) CuI;

5) KCl;

Write in the table the numbers of the selected substances under the corresponding letters.

1. A solution of substance Y was added to a test tube with an alkali solution (substance X). As a result, a reaction occurred that is described by the abbreviated ionic equation OH - + H + = H 2 O. From the proposed list, select substances X and Y that can enter into the described reaction.

1) potassium sulfide;

2) carbonic acid;

3) sulfuric acid;

4) barium hydroxide;

5) sodium hydroxide.

Write in the table the numbers of the selected substances under the corresponding letters.

1. As a result of the interaction of a solution of copper (II) sulfate with iron, salt X was formed. This salt was heated with concentrated sulfuric acid, as a result of which a new salt Y was formed. From the proposed list, select substances X and Y that match the description given.

1) FeS;

2) CuS;

3) FeSO 4 ;

4) FeSO 3 ;

5) Fe 2 (SO 4) 3.

Write in the table the numbers of the selected substances under the corresponding letters.

1. A solution of sodium sulfide was added to a solution of iron(III) chloride, resulting in a precipitate. The resulting precipitate was treated with a solution of sulfuric acid, and part of the precipitate X dissolved. The undissolved part of the precipitate Y was yellow. From the proposed list, select substances X and Y that match the description given.

1) FeS;

2) Fe (OH) 2;

3) Fe 2 S 3;

4) S;

5) Fe(OH) 3 .

Write in the table the numbers of the selected substances under the corresponding letters.

1. Iron(III) chloride was added to a solution of sodium hydroxide, and precipitate X precipitated. The precipitate was separated and dissolved in hydroiodic acid. In this case, substance Y was formed. From the proposed list, select substances X and Y that correspond to the description given.

1) Fe (OH) 2;

2) Fe(OH) 3 ;

3) FeI 3 ;

4) I 2 ;

5) NaCl;

Write in the table the numbers of the selected substances under the corresponding letters.

1. An excess of carbon dioxide was passed through a solution of sodium hydroxide. Substance X thus obtained was isolated from the solution, dried and calcined. This resulted in the formation of a solid Y. From the provided list, select substances X and Y that correspond to the description given.

1) Na 2 CO 3;

2) NaHCO 3 ;

3) HCOONa;

4) Na 2 O 2;

5) Na 2 O.

Write in the table the numbers of the selected substances under the corresponding letters.

Substance X was added to one test tube with a solution of copper(II) chloride, and as a result of the reaction, the formation of a red precipitate was observed. A solution of substance Y was added to another test tube with a solution of copper(II) chloride. As a result of the reaction, an insoluble salt was formed. From the proposed list, select substances X and Y that can enter into the described reactions.

1) zinc;

2) zinc oxide;

3) potassium bromide;

4) silver fluoride;

5) silver.

Write in the table the numbers of the selected substances under the corresponding letters.

1. A few drops of salt solution X were added to one of the tubes with a solution of iron (III) sulfate, and a solution of substance Y was added to the other. As a result, a brown precipitate was observed in each of the tubes. From the proposed list, select substances X and Y that can enter into the described reactions.

1) BaCl 2 ;

2) NH3;

3) Cu(OH) 2 ;

4) K2CO3;

5) AgNO 3 ;

Write in the table the numbers of the selected substances under the corresponding letters.

1. Salt solution X was added to one of the tubes with hydrochloric acid, and substance Y was added to the other. As a result, a colorless, odorless gas was observed in each of the tubes. From the proposed list, select substances X and Y that can enter into the described reactions.

Colorless bright blue-blue

Analytical features of substances and analytical reactions

When conducting qualitative and quantitative analysis, use analytical features of substances and analytical reactions.

Analytical Features – properties of the analyte or the products of its transformation, which make it possible to judge the presence of certain components in it. Characteristic analytical features - color, smell, angle of rotation of the plane of polarization of light, radioactivity, ability to interact with electromagnetic radiation (for example, the presence of characteristic bands in the IR absorption spectra or maxima in the absorption spectra in the visible and UV regions of the spectrum), etc.

Analytical reaction - chemical transformation of the analyte under the action of an analytical reagent with the formation of products with noticeable analytical features. As analytical reactions, the most commonly used reactions are the formation of colored compounds, the release or dissolution of precipitates, gases, the formation of crystals of a characteristic shape, the coloring of a gas burner flame, the formation of compounds that luminesce in solutions, etc. The results of analytical reactions are affected by temperature, concentration of solutions, pH environment, the presence of other substances (interfering, masking, catalyzing processes), etc.

Let's illustrate what has been said with some examples.

Formation of colored compounds. Copper ions Сu 2+ in aqueous solutions, in which they exist in the form of almost colorless (pale bluish) aquacomplexes 2+ , when interacting with ammonia, they form a soluble complex (ammonia) 2+ of bright blue-blue, coloring the solution in the same color:

2+ + 4NH 3 \u003d 2+ + P H 2 O

Using this reaction, it is possible to identify (detect) Cu 2+ copper ions in aqueous solutions.

If colorless (pale yellow) ions of ferric iron Fe 3+ (also in the form of an aquocomplex 3+) are present in an aqueous solution, then with the introduction of thiocyanate ions (thiocyanate ions) NCS - , the solution turns into an intense color due to the formation of complexes 3– n of red color:

3+ + P NCS-=3- n + P H 2 O

where P < или = 6. При этом, в зависимости от отношения концентраций 3+ и NCS – , образуется равновесная смесь комплексов с P= 1; 2; 3; four; 5; 6. All of them are painted red. This reaction is used to discover (detect) iron ions (III).

Note that individual multiply charged ions, for example, Cu 2+, Fe 2+, Fe 3+, Co 3+, Ni 2+, etc., as well as hydrogen ions H + (i.e. protons - nuclei of the hydrogen atom), cannot exist in aqueous solutions under normal conditions, since they are thermodynamically unstable and interact with water molecules or with other particles to form aquocomplexes (or complexes of a different composition):

M m++n H 2 O \u003d [M (H 2 O) n] m +(aquacomplex)

H+ + H 2 O = H 3 O + (hydronium ion)

In what follows, for brevity, in chemical equations we will not always indicate the water molecules that are part of the aquocomplexes, remembering, however, that in fact, the corresponding aquocomplexes, and not “bare” metal or hydrogen cations, participate in reactions in solutions. So, for simplicity, we will write H +, Cu 2+, Fe 2+, etc. instead of the more correct H 3 O + , 2+ , 3+ , respectively, etc.

Isolation or dissolution of precipitates. Ba 2+ ions present in an aqueous solution can be precipitated by adding a solution containing sulfate ions SO 4 2+ in the form of a sparingly soluble white precipitate of barium sulfate:

Ba 2+ + SO 4 2+ \u003d BaSO 4. ↓(white precipitate)

A similar picture is observed during the precipitation of calcium ions Ca 2+ by soluble carbonates:

Ca 2+ + CO 3 2– → CaCO 3 ↓(white precipitate)

The white precipitate of calcium carbonate dissolves under the action of acids, according to the scheme:

CaCO 3 + 2HC1 → CaC1 2 + CO 2 + H 2 O

This releases gaseous carbon dioxide.

Chloroplatinate ions 2– form yellow precipitates upon addition of a solution containing potassium cations K + or ammonium NH + . If a solution of sodium chloroplatinate Na 2 (this salt is quite soluble in water) is treated with a solution of potassium chloride KCl or ammonium chloride NH 4 C1, then yellow precipitates of potassium hexachloroplatinate K 2 or ammonium (NH 4) 2, respectively (these salts are slightly soluble in water):

Na 2 + 2KS1 → K 2 ↓ + 2NaCl

Na 2 + Z NH 4 C1 → (NH 4) 2 ↓ + 2NaCl

Reactions with evolution of gases(outgassing reactions). The reaction of dissolution of calcium carbonate in acids has already been cited above, in which gaseous carbon dioxide is released. Let us point out some more gas-evolving reactions.

If alkali is added to a solution of any ammonium salt, then gaseous ammonia is released, which can be easily determined by the smell or by the blue of wet red litmus paper:

NH 4 + + OH - \u003d NH 3 H 2 0 → NH 3 + H 2 0

This reaction is used in both qualitative and quantitative analysis.

Sulfides under the action of acids emit gaseous hydrogen sulfide:

S 2– + 2H + → H 2 S

which is easily felt by the specific smell of rotten eggs.

Formation of characteristic crystals(microcrystalloscopic reactions). Sodium ions Na + in a drop of solution, when interacting with hexahydroxoantibate (V) ions, form white crystals of sodium hexahydroxoantibate (V) Na of a characteristic shape:

Na + + -- = Na

The shape of the crystals is clearly visible when viewed under a microscope. This reaction is sometimes used in qualitative analysis to discover sodium cations.

Potassium ions K + when reacting in neutral or acetic acid solutions with soluble sodium and lead hexanitrocuprate (P) Na 2 Pb form black (or brown) crystals of potassium and lead hexanitrocuprate (P) K 2 Pb [Cu (N0 2) 6] characteristic cubic forms that can also be seen when viewed under a microscope. The reaction proceeds according to the scheme:

2K + + Na 2 Pb \u003d K 2 Pb [Cu (N0 3) 6] + 2Na +

It is used in qualitative analysis to detect ( discoveries) potassium cations. Microcrystalloscopic analysis was first introduced into analytical practice in 1794-1798. member of the St. Petersburg Academy of Sciences T.E. Lovitz.

Coloring the flame of a gas burner. When compounds of some metals are introduced into the flame of a gas burner, the flame is colored in one color or another, depending on the nature of the metal. Thus, lithium salts color the flame carmine-red, sodium salts yellow, potassium salts violet, calcium salts brick-red, barium salts yellow-green, etc.

This phenomenon can be explained as follows. When a compound of a given metal (for example, its salt) is introduced into the flame of a gas burner, this compound decomposes. The metal atoms formed during the thermal decomposition of the compound are excited at a high temperature of the flame of a gas burner, i.e., absorbing a certain portion of thermal energy, they pass into some kind of excited electronic state that has more energy compared to the unexcited (ground) state. The lifetime of the excited electronic states of atoms is negligible (very small fractions of a second), so that the atoms almost instantly return to the unexcited (ground) state, emitting the absorbed energy in the form of light radiation with a particular wavelength, depending on the energy difference between the excited and the ground the energy levels of the atom. For atoms of different metals, this energy difference is not the same and corresponds to light radiation of a certain wavelength. If this radiation lies in the visible region of the spectrum (in the red, yellow, green or some other part of it), then the human eye fixes one or another color of the burner flame. The coloration of the flame is short-term, since the metal atoms are carried away with the gaseous products of combustion.

The coloring of a gas burner flame with metal compounds is used in qualitative analysis to discover metal cations that emit radiation in the visible region of the spectrum. The atomic absorption (fluorescent) methods of element analysis are also based on the same physicochemical nature.

In table. 3.1 shows examples of burner flame colors from some elements.

Let's imagine the following situation:

You work in a lab and decide to do an experiment. To do this, you opened the cabinet with reagents and suddenly saw the following picture on one of the shelves. Two jars of reagents had their labels peeled off, which were safely left lying nearby. At the same time, it is no longer possible to determine exactly which jar corresponds to which label, and the external signs of the substances by which they could be distinguished are the same.

In this case, the problem can be solved using the so-called qualitative reactions.

Qualitative reactions called such reactions that allow you to distinguish one substance from another, as well as to find out the qualitative composition of unknown substances.

For example, it is known that the cations of some metals, when their salts are added to the burner flame, color it in a certain color:

This method can only work if the substances to be distinguished change the color of the flame in different ways, or one of them does not change color at all.

But, let's say, as luck would have it, the substances you determine do not color the color of the flame, or color it in the same color.

In these cases, it will be necessary to distinguish substances using other reagents.

In what case can we distinguish one substance from another with the help of any reagent?

There are two options:

• One substance reacts with the added reagent, while the other does not. At the same time, it must be clearly seen that the reaction of one of the starting substances with the added reagent has really passed, that is, some external sign of it is observed - a precipitate has formed, a gas has been released, a color change has occurred, etc.

For example, it is impossible to distinguish water from a sodium hydroxide solution using hydrochloric acid, despite the fact that alkalis react perfectly with acids:

NaOH + HCl \u003d NaCl + H 2 O

This is due to the absence of any external signs of a reaction. A transparent colorless solution of hydrochloric acid, when mixed with a colorless hydroxide solution, forms the same transparent solution:

But on the other hand, water can be distinguished from an aqueous solution of alkali, for example, using a solution of magnesium chloride - a white precipitate forms in this reaction:

2NaOH + MgCl 2 = Mg(OH) 2 ↓+ 2NaCl

2) Substances can also be distinguished from each other if they both react with the added reagent, but do so in different ways.

For example, a solution of sodium carbonate can be distinguished from a solution of silver nitrate using a solution of hydrochloric acid.

hydrochloric acid reacts with sodium carbonate to release a colorless, odorless gas - carbon dioxide (CO 2):

2HCl + Na 2 CO 3 \u003d 2NaCl + H 2 O + CO 2

and with silver nitrate to form a white cheesy precipitate AgCl

HCl + AgNO 3 \u003d HNO 3 + AgCl ↓

The tables below show different options for detecting specific ions:

Qualitative reactions to cations

Cation	Reagent	Sign of reaction
Ba 2+	SO 4 2-	Ba 2+ + SO 4 2- \u003d BaSO 4 ↓
Cu2+		1) Precipitation of blue color: Cu 2+ + 2OH - \u003d Cu (OH) 2 ↓ 2) Precipitation of black color: Cu 2+ + S 2- \u003d CuS ↓
Pb 2+	S2-	Precipitation of black color: Pb 2+ + S 2- = PbS↓
Ag+	Cl-	Precipitation of a white precipitate, insoluble in HNO 3, but soluble in ammonia NH 3 H 2 O: Ag + + Cl − → AgCl↓
Fe2+	2) Potassium hexacyanoferrate (III) (red blood salt) K 3	1) Precipitation of a white precipitate that turns green in air: Fe 2+ + 2OH - \u003d Fe (OH) 2 ↓ 2) Precipitation of a blue precipitate (turnbull blue): K + + Fe 2+ + 3- = KFe↓
Fe3+	2) Potassium hexacyanoferrate (II) (yellow blood salt) K 4 3) Rhodanide ion SCN −	1) Precipitation of brown color: Fe 3+ + 3OH - \u003d Fe (OH) 3 ↓ 2) Precipitation of a blue precipitate (Prussian blue): K + + Fe 3+ + 4- = KFe↓ 3) The appearance of intense red (blood red) staining: Fe 3+ + 3SCN - = Fe(SCN) 3
Al 3+	Alkali (hydroxide amphoteric properties)	Precipitation of a white precipitate of aluminum hydroxide when a small amount of alkali is added: OH - + Al 3+ \u003d Al (OH) 3 and its dissolution upon further addition: Al(OH) 3 + NaOH = Na
NH4+	OH − , heating	Emission of gas with a pungent odor: NH 4 + + OH - \u003d NH 3 + H 2 O Blue wet litmus paper
H+ (acid environment)	Indicators: − litmus − methyl orange	Red staining

Qualitative reactions to anions

Anion	Impact or reagent	Reaction sign. Reaction equation
SO 4 2-	Ba 2+	Precipitation of a white precipitate, insoluble in acids: Ba 2+ + SO 4 2- \u003d BaSO 4 ↓
NO 3 -	1) Add H 2 SO 4 (conc.) and Cu, heat 2) A mixture of H 2 SO 4 + FeSO 4	1) Formation of a blue solution containing Cu 2+ ions, brown gas evolution (NO 2) 2) The appearance of the color of nitroso-iron sulfate (II) 2+. Violet to brown color (brown ring reaction)
PO 4 3-	Ag+	Precipitation of a light yellow precipitate in a neutral medium: 3Ag + + PO 4 3- = Ag 3 PO 4 ↓
CrO 4 2-	Ba 2+	Precipitation of a yellow precipitate, insoluble in acetic acid, but soluble in HCl: Ba 2+ + CrO 4 2- = BaCrO 4 ↓
S2-	Pb 2+	Black precipitation: Pb 2+ + S 2- = PbS↓
CO 3 2-		1) Precipitation of a white precipitate, soluble in acids: Ca 2+ + CO 3 2- \u003d CaCO 3 ↓ 2) Emission of a colorless gas ("boiling"), causing the lime water to become cloudy: CO 3 2- + 2H + = CO 2 + H 2 O
CO2	Lime water Ca(OH) 2	Precipitation of a white precipitate and its dissolution upon further passage of CO 2: Ca(OH) 2 + CO 2 = CaCO 3 ↓ + H 2 O CaCO 3 + CO 2 + H 2 O \u003d Ca (HCO 3) 2
SO 3 2-	H+	SO 2 gas evolution with a characteristic pungent odor (SO 2): 2H + + SO 3 2- \u003d H 2 O + SO 2
F-	Ca2+	Precipitation of a white precipitate: Ca 2+ + 2F - = CaF 2 ↓
Cl-	Ag+	Precipitation of a white cheesy precipitate, insoluble in HNO 3 but soluble in NH 3 H 2 O (conc.): Ag + + Cl - = AgCl↓ AgCl + 2(NH 3 H 2 O) =) Related publications “What is useful yarrow? Yarrow comes across everywhere, but not everyone knows how much health this seemingly inconspicuous plant carries. It cures many diseases... Tips and tricks on how to cure cervical erosion without cauterization The main advantage of the treatment of erosion by means of alternative medicine is the natural basis of the prepared medicines. They carefully...