You will need
- The table of solubility of acids, salts, bases
Acid is complex substances that consist of atoms of hydrogen and acidstion of residues, for example, hydrochloric (HCl), sulfuric (H2SO4), nitric (HNO3).
The Foundation is a complex substances that consist of atoms of metals and of hydroxyl groups. Water soluble bases are called alkalis. These include such compounds as sodium hydroxide (NaOH), calcium hydroxide (Ca(OH)2), potassium hydroxide (KOH), and others. Their solubility can be determined according to the table, as it is reference material, which along with the table of D. I. Mendeleev required on all types of control, including the exam in chemistry (in each CIMA).
The interaction of acids with alkalis is otherwise known as neutralization reaction, so as to produce salt and water. The salt may be formed as the middle, and sour. Also similar to the interaction of substances can be attributed to the exchange reaction because of the acids and alkalis are exchanged between its constituent parts.
Example No. 1. Write the reaction equation of interaction of hydrochloric acidwith sodium hydroxide. In this reaction an atom of hydrogen in hydrochloric acid (HCl) changes places with the sodium atom in the alkali - sodium hydroxide (NaOH). The result is a salt – sodium chloride (NaCl) and water (H2O). Thus, the alkali neutralized the acid. In this reaction equation arrange the coefficients is not necessary, as the number of atoms of each element that is included as original substances and reaction products, is the same. HCl + NaOH = NaCl + Н2ОАналогично, without the coefficients will look like the equation, if for the reaction to take of nitric acid (HNO3) and potassium hydroxide (KOH).HNO3 + KOH = KNO3 + H2O
Example No. 2. Write the reaction equation of interaction of sulfuric acid, (H2SO4) with calcium hydroxide (Ca(OH)2). In this reaction equation 2 hydrogen atoms of sulfuric acid, (H2SO4) menyayutsya one calcium atom included in alkali – calcium hydroxide (Ca(OH)2). Asáaáresult, the formed salt is calcium sulfate (CaSO4) and water (H2O). Arrange the necessary factors by the method of substitution, increasing the number of water molecules to 2.H2SO4 + Ca(OH)2 = CaSO4 + 2H2O
Example No. 3. Write the reaction equation of interaction of sulfuric acid, (H2SO4) with sodium hydroxide (NaOH). If a job is not specifically set forth the conditions of the reaction, it is assumed that salt will be formed only average - in this case sodium sulfate (Na2SO4).H2SO4 + 2NaOH = Na2SO4 + 2Н2ООднако if the condition says that the reaction occurs with an excess of acids (or concentrated), in this case, a salt acid – hydrosulfate sodium (nahso4 solution)H2SO4 + NaOH = nahso4 solution + 2H2O
In the arrangement of the coefficients remember that the number of atoms of each element of the original substances must be the same number of atoms of the elements in the reaction products.
Advice 2 : How to determine base of salt
Salt – a chemical substance consisting of a cation, i.e. a positively charged ion, and the negatively charged metal anion acid residue. Many types of salts: normal, acidic, basic, double, mixed, hydrate, complex. It depends on the compositions of the cation and anion. How to determine base of salt?
Suppose you have four identical containers with hot solutions. You know it – solutions lithium carbonate, sodium carbonate, potassium carbonate and barium carbonate. Your task is to determine which salt is contained in each tank.
Think of the physical and chemical properties of compounds of these metals. Lithium, sodium, potassium – the alkali metals the first group, their properties are very similar, the activity increases from lithium to potassium. Barium – alkaline earth metal of the second group. Its carbonate salt is highly soluble in hot water but poorly soluble in cold. Stop! That's the first opportunity to determine which container contains barium carbonate.
Cool capacity, such as by placing them in the vessel with ice. Three of the solution will remain transparent, and the fourth will quickly turbid, will begin to precipitate a white precipitate. Here in it and there is the salt of barium. Put the container in the direction.
You can quickly determine barium carbonate. Alternately cast a little of the solution into another container with a solution of any sulphate salt (e.g. sodium sulphate). Only ions of barium, contacting the sulfate-ions, instantly form a dense white precipitate.
So, barium carbonate you have identified. But how do you distinguish salts three alkali metals? It is quite simple to make, you'll need a porcelain Cup for evaporation and a spirit lamp.
Pour a small amount of each solution into a separate porcelain Cup and evaporate the water on the flame of a spirit lamp. Formed small crystals. Put them in the flame of a spirit lamp or a Bunsen burner – with steel tweezers or porcelain spoon. Your task is to notice the color of the outbreak of the "tongue" of flame. If it is a salt of lithium the color will be bright red. The sodium will color the flame a rich yellow color, and potassium in the Magenta-purple. By the way, if likewise experienced a salt of barium flame color should have been green.
A famous chemist in his youth, about the same exposed greedy landlady. He sprinkled the remains of half-eaten meals lithium chloride – a substance is completely harmless in small quantities. The next day at lunch a piece of meat served in the dishes were burned in front of the spectroscope and the residents of the guest house saw a bright red strip. The hostess prepared the meal from yesterday's leftovers.