AlexBr 07-02-2010 09:30
There are two blades from our blacksmiths, shx 15 (bearing), I want to etch them with hydrochloric acid, I heard about the interesting results of this process.
They brought me acid, they said it was concentrated.
Now the question is how can I bring it up to 5-10% as needed for etching. Those. should I pour water there or into water and how much if the acid is 100 ml?
I understand the question is a loser, but I finished school and college a long time ago, and I don’t want to learn from my mistakes.
serber 07-02-2010 10:09
Only acid in water! In 1 liter of water 100 ml of HCl, we get a 10% solution
chief 07-02-2010 10:19
quote: Originally posted by serber:
Only acid in water! In 1 liter of water 100 ml of HCl, we get a 10% solution
We won’t get 10%!
Concentrated hydrochloric acid is not sulfuric acid; by definition it cannot be 100 percent, because hydrogen chloride is a gas.
Concentrated HCl - about 35-38 percent. Therefore, it is necessary to dilute approximately three times, and not ten times. If you need to be precise - by density:
http://ru.wikipedia.org/wiki/Hydrochloric acid
hunter1957 07-02-2010 10:29
The maximum achievable concentration of hydrochloric acid is 38-39%; then do the math yourself to get 5% acid. Regarding steel etching there is such a thing that concentrated acids passivate the steel surface and the oxide film prevents further etching.
pereira71 07-02-2010 11:41
Hello!
Now I’ll try to post a table with which you can calculate the percentage dilution of acids. Thanks to our Estonian colleagues.
Damn, it doesn't work...
If possible, let me send it to someone for soap, and you can attach it. Excel file.
Nestor74 07-02-2010 12:55
pereira71
so put it somewhere on any file hosting service, and here it is, using cntrl-C cntrl-V, and that’s fine.
Kerogen 07-02-2010 13:32
quote: Originally posted by AleksBr:
Now the question is how can I bring it up to 5-10% as needed for etching. Those. should I pour water there or into water and how much if the acid is 100 ml?
Dilution calculator
pereira71 07-02-2010 13:54
While I was calving it was already done)))
Thanks Kerogen!
07-02-2010 16:28
Dilute 3-4 times, you will get what you need. What about
quote: Only acid in water!
I beg to differ, SALT can be stirred in any way you like. And SULFURIC acid is really only added to the water in a thin stream while stirring, and certainly in a container that will not crack due to strong heating of the mixture.
And to prepare solutions of other concentrations, I advise you to use the rule of the cross, look here for example
1.2679; G crit 51.4°C, p crit 8.258 MPa, d crit 0.42 g/cm 3 ; -92.31 kJ/, DH pl 1.9924 kJ/ (-114.22°C), DH isp 16.1421 kJ/ (-8.05°C); 186.79 J/(mol K); (Pa): 133.32 10 -6 (-200.7 °C), 2.775 10 3 (-130.15 °C), 10.0 10 4 (-85.1 °C), 74, 0 10 4 (-40°C), 24.95 10 5 (O °C), 76.9 10 5 (50 °C); level of temperature dependence logp(kPa) = -905.53/T+ 1.75lgT- -500.77·10 -5 T+3.78229 (160-260 K); coefficient 0.00787; g 23 mN/cm (-155°C); r 0.29 10 7 Ohm m (-85°C), 0.59 10 7 (-114.22°C). See also table. 1.
R-value of HC1 at 25 °C and 0.1 MPa (mol %): in pentane - 0.47, hexane - 1.12, heptane - 1.47, octane - 1.63. The P-rhythm of HC1 in alkyl and aryl halides is low, for example. 0.07 / for C 4 H 9 C1. The pH value in the range from -20 to 60° C decreases in the series dichloroethane-tri-chloroethane-tetrachloroethane-trichlorethylene. The pH value at 10°C in a series is approximately 1/, in carbon ethers it is 0.6/, in carbonic compounds it is 0.2/. Stable R 2 O · HCl are formed. The P-rhythm of HC1 in obeys and is for KCl 2.51·10 -4 (800°С), 1.75·10 -4 / (900°С), for NaCl 1.90·10 -4 / (900° WITH).
Salt room. HCl in water is highly exothermic. process, for endless dilution. water solution D H 0 HCl -69.9 kJ/, Cl -- 167.080 kJ/; HC1 is completely ionized. The pH value of HC1 depends on the temperature (Table 2) and the partial HC1 in the gas mixture. Density of salt decomposition. and h at 20 °C are presented in table. 3 and 4. As the temperature increases, h hydrochloric acid decreases, for example: for 23.05% hydrochloric acid at 25 °C h 1364 mPa s, at 35 °C 1.170 mPa s hydrochloric acid containing h per 1 HC1, is [kJ/(kg K)]: 3.136 (n = 10), 3.580 (n = 20), 3.902 (n = 50), 4.036 (n = 100), 4.061 (n = 200).
HCl forms c (Table 5). In the HCl-water system there are three eutectics. points: - 74.7 °C (23.0% by weight HCl); -73.0°C (26.5% HCl); -87.5°C (24.8% HC1, metastable phase). Known HCl nH 2 O, where n = 8. 6 (mp. -40 ° C), 4. 3 (mp. -24.4 ° C), 2 (mp. -17.7 °C) and 1 (mp -15.35°C). crystallizes from 10% hydrochloric acid at -20, from 15% at -30, from 20% at -60 and from 24% at -80°C. The P-value of halides decreases with increasing HCl in hydrochloric acid, which is used for their.
Chemical properties. Pure dry HCl begins to dissociate above 1500°C and is chemically passive. Mn. , C, S, P do not interact. even with liquid HCl. C, reacts above 650 °C, with Si, Ge and B-c present. AlCl 3, with transition metals - at 300 °C and above. It is oxidized by O 2 and HNO 3 to Cl 2, with SO 3 it gives C1SO 3 H. About the solutions with org. connections see .
WITH Olina is chemically very active. Dissolves with the release of H 2 everything that has a negative. ,with me. and forms, releases free. who are you from people like , etc.
Receipt. In the HCl industry, the following is obtained. methods - sulfate, synthetic. and from exhaust gases (by-products) of a number of processes. The first two methods lose their meaning. Thus, in the USA in 1965 the share of waste hydrochloric acid was 77.6% of the total production volume, and in 1982 - 94%.
The production of hydrochloric acid (reactive, obtained by the sulfate method, synthetic, waste gas) is to obtain HCl from the last. his . Depending on the method of heat removal (reaches 72.8 kJ/), processes are divided into isothermal, adiabatic. and combined.
The sulfate method is based on interaction. NaCl with conc. H 2 SO 4 at 500-550 ° C. Reaction contain from 50-65% HCl (muffle) to 5% HCl (reactor with). It is proposed to replace H 2 SO 4 with a mixture of SO 2 and O 2 (process temperature approx. 540 °C, cat. Fe 2 O 3).
The direct synthesis of HCl is based on a chain reaction: H 2 + Cl 2 2HCl + 184.7 kJ K p is calculated by the equation: logK p = 9554/T- 0.5331g T+ 2.42.
The reaction is initiated by light, moisture, solid porous (, porous Pt) and certain minerals. in-you ( , ). Synthesis is carried out with an excess of H 2 (5-10%) in combustion chambers made of steel and refractory bricks. Naib. modern material that prevents HCl contamination - graphite, impregnated phenol-formal. resins. To prevent explosiveness, mix directly in the burner flame. To the top. the combustion chamber area is installed to cool the reaction. up to 150-160°C. Power modern graphite reaches 65 tons/day (in terms of 35% salt). In case of H2 deficiency, dil. is used. process modifications; for example, pass a mixture of Cl 2 and water through a layer of porous hot water:
2Cl 2 + 2H 2 O + C: 4HCl + CO 2 + 288.9 kJ
The temperature of the process (1000-1600 °C) depends on the type and presence of impurities in it, which are (for example, Fe 2 O 3). It is promising to use a mixture of CO with:
CO + H 2 O + Cl 2: 2HCl + CO 2
More than 90% of hydrochloric acid in developed countries is obtained from waste HCl, formed during the dehydrochlorination of org. compounds, chlororg. waste, obtaining non-chlorinated potash. etc. Abgases contain various. quantity of HC1, inert impurities (N 2, H 2, CH 4), poorly soluble in org. substances (,), water-soluble substances (acetic acid), acidic impurities (Cl 2, HF, O 2) and. Application of isothermal advisable when the content of HC1 in exhaust gases is low (but when the content of inert impurities is less than 40%). Naib. Film ones are promising, making it possible to extract from 65 to 85% HCl from the initial exhaust gas.
Naib. Adiabatic schemes are widely used. . Abgases are introduced into the lower part, and (or diluted salt) - countercurrent to the upper one. The salt water is heated to temperature due to the heat of HCl. The change in temperature and HCl is shown in Fig. 1. The temperature is determined by the temperature corresponding to the temperature (max. boiling point of the azeotropic mixture - approx. 110°C).
In Fig. 2 shows a typical adiabatic circuit. HCl from exhaust gases formed during (eg, production). HCl is absorbed in 1, and the residues are poorly soluble in org. the substances are separated from the after in apparatus 2, further purified in the tail column 4 and separators 3, 5 and commercial salt is obtained.
Rice. 1. T-p distribution diagram (curve 1) and
Instructions
Take a test tube that supposedly contains hydrochloric acid (HCl). Add a little to this container solution silver nitrate (AgNO3). Proceed with caution and avoid contact with skin. Silver nitrate can leave black marks on the skin, which can only be removed after a few days, and salt exposure on the skin acids may cause severe burns.
Watch what happens to the resulting solution. If the color and consistency of the contents of the test tube remain unchanged, this will mean that the substances have not reacted. In this case, it will be possible to conclude with confidence that the substance being tested was not .
If a white precipitate appears in the test tube, the consistency of which resembles cottage cheese or curdled milk, this will indicate that the substances have reacted. The visible result of this reaction was the formation of silver chloride (AgCl). It is the presence of this white cheesy sediment that will be direct evidence that initially there was indeed hydrochloric acid in your test tube, and not any other acid.
Pour some of the test liquid into a separate container and drop in a little lapis solution. In this case, a “curdy” white precipitate of insoluble silver chloride will instantly form. That is, there is definitely a chloride ion in the molecule of the substance. But maybe it’s not, after all, but a solution of some kind of chlorine-containing salt? For example, sodium chloride?
Remember another property of acids. Strong acids(and hydrochloric acid is certainly one of them) can displace weak acids from them. Place a little soda powder - Na2CO3 - in a flask or beaker and slowly add the liquid to be tested. If there is a hissing sound immediately and the powder literally “boils”, there will be no doubt left - it is hydrochloric acid.
Why? Because this reaction is: 2HCl + Na2CO3 = 2NaCl + H2CO3. Carbonic acid is formed, which is so weak that it instantly decomposes into water and carbon dioxide. It was his bubbles that caused this “boiling and hissing.”
Receipt. Hydrochloric acid is produced by dissolving hydrogen chloride in water.
Pay attention to the device shown in the figure on the left. It is used to produce hydrochloric acid. During the process of obtaining hydrochloric acid, monitor gas outlet pipe, it should be near the water level, and not immersed in it. If this is not monitored, then due to the high solubility of hydrogen chloride, water will enter the test tube with sulfuric acid and an explosion may occur.
In industry, hydrochloric acid is usually produced by burning hydrogen in chlorine and dissolving the reaction product in water.
Physical properties. By dissolving hydrogen chloride in water, you can even obtain a 40% solution of hydrochloric acid with a density of 1.19 g/cm 3 . However, commercially available concentrated hydrochloric acid contains about 0.37 parts by weight, or about 37% hydrogen chloride. The density of this solution is approximately 1.19 g/cm 3 . When an acid is diluted, the density of its solution decreases.
Concentrated hydrochloric acid is an invaluable solution, smoking strongly in humid air, which has a pungent odor due to the release of hydrogen chloride.
Chemical properties. Hydrochloric acid has a number of general properties that are characteristic of most acids. In addition, it has some specific properties.
Properties of HCL common to other acids: 1) Change in color of indicators 2) interaction with metals 2HCL + Zn → ZnCL 2 + H 2 3) Interaction with basic and amphoteric oxides: 2HCL + CaO → CaCl 2 + H 2 O; 2HCL + ZnO → ZnHCL 2 + H 2 O 4) Interaction with bases: 2HCL + Cu (OH) 2 → CuCl 2 + 2H 2 O 5) Interaction with salts: 2HCL + CaCO 3 → H 2 O + CO 2 + CaCL 2
Specific properties of HCL: 1) Interaction with silver nitrate (silver nitrate is a reagent for hydrochloric acid and its salts); a precipitate will form white, which does not dissolve in water or acids: HCL + AgNO3 → AgCL↓ + HNO 3 2) Interaction with oxidizing agents (MnO 2, KMnO, KCLO 3, etc.): 6HCL + KCLO 3 → KCL +3H 2 O + 3CL 2
Application. A huge amount of hydrochloric acid is consumed to remove iron oxides before coating products made from this metal with other metals (tin, chromium, nickel). In order for hydrochloric acid to react only with oxides, but not with the metal, special substances called inhibitors are added to it. Inhibitors– substances that slow down reactions.
Hydrochloric acid is used to produce various chlorides. It is used to produce chlorine. Very often, a solution of hydrochloric acid is prescribed to patients with low acidity of gastric juice. Hydrochloric acid is found in everyone's body; it is part of the gastric juice, which is necessary for digestion.
IN Food Industry hydrochloric acid is used only in the form of a solution. It is used to regulate acidity during production citric acid, gelatin or fructose (E 507).
Do not forget that hydrochloric acid is dangerous for the skin. It poses an even greater danger to the eyes. When affecting a person, it can cause tooth decay, irritation of mucous membranes, and suffocation.
In addition, hydrochloric acid is actively used in electroplating and hydrometallurgy (removal of scale, rust, leather treatment, chemical reagents, as a rock solvent in oil production, in the production of rubbers, monosodium glutamate, soda, Cl 2). Hydrochloric acid is used for the regeneration of Cl 2 in organic synthesis (for the production of vinyl chloride, alkyl chlorides, etc.) It can be used as a catalyst in the production of diphenylolpropane, benzene alkylation.
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In water it is called hydrochloric acid ( HCl).
Physical properties of hydrochloric acid
Under ordinary conditions, hydrochloric acid is a clear, colorless liquid with a strong, unpleasant odor.
Concentrated hydrochloric acid contains 37% hydrogen chloride. This acid “smoke” in air. Hydrogen chloride is released from it, which, with water vapor in the air, forms a “fog” consisting of small droplets of hydrochloric acid. Hydrochloric acid is slightly heavier than water ( specific gravity 37% hydrochloric acid is 1.19).
In school laboratories they use for the most part dilute hydrochloric acid.
Chemical properties of hydrochloric acid
Hydrochloric acid solution has a sour taste. Litmus in this solution is red, but phenolphthalein remains colorless.
Substances whose color changes due to the action of alkalis and acids are called indicators.
Litmus, phenolphthalein - indicators for acids and alkalis. Using indicators, you can determine whether there is an acid or alkali in a solution.
Hydrochloric acid reacts with many metals. The interaction of hydrochloric acid with sodium occurs especially rapidly. This can be easily verified by experiment, which can be carried out in the device.
Concentrated hydrochloric acid is poured into a test tube to approximately 1/4 of its volume, secured in a stand and a small piece of sodium (the size of a pea) is dropped into it. Hydrogen is released from the test tube, which can be set on fire, and small crystals of table salt settle to the bottom of the test tube.
From this experiment it follows that sodium displaces hydrogen from the acid and combines with the rest of its molecule:
2Na + 2HCl = 2NaCl + H2?
When hydrochloric acid acts on zinc, hydrogen is released, and the substance zinc chloride ZnCl 2 remains in the solution.
Since zinc is divalent, each zinc atom replaces two hydrogen atoms in two molecules of hydrochloric acid:
Zn + 2HCl = ZnCl 2 + H 2?
Hydrochloric acid also acts on iron, aluminum and many other metals.
As a result of these reactions, hydrogen is released, and chloride metals remain in solutions: ferric chloride FeCl 2, aluminum chloride AlCl 3, etc.
These metal chlorides are products of the replacement of hydrogen in hydrochloric acid with metals.
Complex substances that can be considered as products of the substitution of a metal for the hydrogen of an acid are called salts.
Metal chlorides are salts of hydrochloric acid.
Neutralization reaction (equation)
Very important chemical property hydrochloric acid is its interaction with bases. Let us first consider its interaction with alkalis, for example with caustic soda.
For this purpose, pour a small amount of diluted sodium hydroxide solution into a glass glass and add a few drops of litmus solution to it.
The liquid will turn blue. Then we will pour in small portions into the same glass a solution of hydrochloric acid from a graduated tube (burette) until the color of the liquid in the glass turns purple. The violet color of litmus indicates that the solution contains neither acid nor alkali.
This solution is called neutral. After boiling the water out of it, there will be salt NaCl. Based on this experience, we can conclude that when solutions of sodium hydroxide and hydrochloric acid are combined, water and sodium chloride are obtained. Water molecules are formed from the combination of hydrogen atoms (from acid molecules) with hydroxyl groups (from alkali molecules). Molecules sodium chloride formed from sodium atoms (from alkali molecules) and chlorine atoms - acid residues. The equation for this reaction can be written as follows:
Na |OH + H| Cl = NaCl + H2O
Other alkalis also react with hydrochloric acid - caustic potassium, caustic calcium.
Let's get acquainted with how hydrochloric acid reacts with insoluble bases, for example, copper oxide hydrate. For this purpose, we will place a certain amount of this base in a glass and carefully pour hydrochloric acid into it until the copper oxide hydrate is completely dissolved.
After evaporation of the blue solution thus obtained, crystals of copper chloride CuCl 2 are obtained. Based on this, we can write the following equation:
And in this case, a reaction similar to the interaction of this acid with alkalis occurred: hydrogen atoms from acid molecules combined with hydroxyl groups from base molecules, and water molecules were formed. Copper atoms combined with chlorine atoms (residues from acid molecules) and formed salt molecules - copper chloride.
Hydrochloric acid reacts in the same way with other insoluble bases, for example with iron oxide hydrate:
Fe(OH) 3 + 3HCl = 3H 2 O + FeCl 3
The reaction of an acid with a base to produce salt and water is called neutralization.
Hydrochloric acid is found in small quantities in gastric juice humans and animals and plays an important role in digestion.
Hydrochloric acid is used to neutralize alkalis and produce chloride salts. It also finds application in the production of certain plastics and medicines.
Application of hydrochloric acid
Hydrochloric acid is widely used in the national economy, and you will often encounter it when studying chemistry.
Large quantities of hydrochloric acid are used to pickle steel. Nickel-plated, galvanized, tin-plated (tin-plated), and chrome-plated products are widely used in everyday life. To coat steel products and sheet iron with a layer of protective metal, you must first remove the film of iron oxides from the surface, otherwise the metal will not stick to it. Removal of oxides is achieved by etching the product with hydrochloric or sulfuric acid. The disadvantage of etching is that the acid reacts not only with the oxide, but also with the metal. To avoid this, a small amount of inhibitor is added to the acid. Inhibitors are substances that slow down an unwanted reaction. Inhibited hydrochloric acid can be stored in steel containers and transported in steel tanks.
A solution of hydrochloric acid can also be bought at a pharmacy. Doctors prescribe a diluted solution to patients with low acidity gastric juice.
