Advice 1: How to define strong and weak electrolytes

Electrolytes are substances, alloys of substances or fluids that have the ability to electrolytically conduct a galvanic current. To determine which electrolytes a substance, applying the theory of electrolytic dissociation.
How to define strong and weak electrolytes
The essence of this theory is that the melting (dissolving in water) almost all electrolytes are decomposed into ions which are positively or negatively charged (which is called electrolytic dissociation). Under the influence of the electric current is negative (anions "-") move to the anode ( + ) and positively charged (cation,+) to move to the cathode (-). Electrolytic dissociation is a reversible process (the reverse process is called "polaryzacja").
Degree (a) electrolytic dissociation is dependent on the nature of the electrolyte, solvent, and concentration. It is the ratio of the number of molecules (n) that fell apart into ions to the total number introduced into the solution of molecules (N). Get: a = n / n
Therefore, strong electrolytes - substances, disintegrating completely into ions when dissolved in water. For strong electrolytes, as a rule, are substances with ionic bonds or silnoroslye: this salt is very soluble, strong acid (HCl, HI, HBr, HClO4, HNO3, H2SO4) and strong bases (KOH, NaOH, RbOH, Ba(OH)2, CsOH, Sr(OH)2, LiOH, Ca(OH)2). In a strong electrolyte is a substance dissolved in it, is mostly in the form of ions (anions and cations); molecules that medicationabana - almost none.
Weak electrolytes - substances which dissociate into ions only partly. Weak electrolytes together with ions in a solution containing molecules medicationabana. Weak electrolytes do not give to the solution high concentrations of ions.

To weak include:
- organic acids (almost all) (C2H5COOH, CH3COOH, etc.);
some of the inorganic acids (H2S, H2CO3, etc.);
- almost all of the salt, slightly soluble in water, ammonium hydroxide, as well as all grounds (Ca3(PO4)2; Cu(OH)2; Al(OH)3; NH4OH);
- water.

They practically do not conduct electricity or conduct, but bad.
Although pure water conducts electricity very poorly, she still has measurable electrical conductivity and explain the fact that water is slightly dissociated into hydroxide ions and hydrogen ions.
Useful advice
Most electrolytes – substances aggressive, so when handling them be very careful and observe safety rules.

Advice 2: How to determine a strong base

Strong base - an inorganic chemical compound formed the hydroxyl group -HE and alkaline (group I elements of the periodic system: Li, K, Na, RB, Cs) or alkaline earth metal (elements in group II Ba, Ca). Written as formula LiOH, KOH, NaOH, RbOH, CsOH, CA(Oh) co₂, VA(HE) and co₂.
How to determine a strong base
You will need
  • varicella Cup
  • burner
  • indicators
  • the metal rod
  • NRO
Strong bases exhibit chemical properties that are typical of all hydroxides. The presence of alkali in the solution is determined by a colour change of the indicator. To the test with the test solution, add methylorange, lower phenolphthalein or litmus test. Methylorange gives a yellow color, phenolphthalein purple and litmus paper turns blue. The stronger the base is, the more intensely colored indicator.
If you want to know what alkali is present, then conduct a qualitative analysis of the solutions. The most common strong bases – hydroxides of lithium, potassium, sodium, barium and calcium. Bases react with acids (neutralization) to form salt and water. It is possible to distinguish CA(Oh) co₂, VA(IT) co₂ and LiOH. When interacting with phosphoric acid formed insoluble precipitates. Other hydroxides precipitation will not, because all salts are soluble K and Na.
3 CA(Oh) co₂ + 2 NRA --→ Ca₃(PO₄)co₂↓+ 6 NO

3 VA(IT) co₂ +2 NRA --→ V(PO₄)co₂↓+ 6 NO

3 LiOH + NO --→ Li₃РО₄↓ + 3 NO
Strain them and dry. Make dried precipitation in the flame. By a colour change of the flame color to determine the ions of lithium, calcium and barium. Accordingly, you define where a hydroxide. Lithium salts color the flame of the burner in Carmine-red color. Barium salts – green, and calcium salts in crimson.
The remaining alkali to form a soluble orthophosphate.

3 NaOH + NO--→ Na₃РО₄ + 3 NO

3 KOH + NO--→ CRO + 3 NO

You must evaporate the water to dry residue. The evaporated salt on a metal rod alternately enter into the flame. Where is the sodium salt, the flame will turn a bright yellow color, and orthophosphate of the potassium – pink-purple. Thus, having a minimal set of equipment and reagents you have identified all the data you a strong Foundation.

Advice 3: How to identify strong electrolytes

Electrolyte – a substance that in the solid state is an insulator, i.e. does not conduct electric current, however, in dissolved or molten form becomes a conductor. Why is such an abrupt change in properties? The fact that the molecules of an electrolyte in solutions or melts dissociate into positively charged and negatively charged ions, whereby these substances in such aggregate as is capable of conducting an electric current. Electrolytic properties of most salts, acids, bases.
How to identify strong electrolytes
All electrolytes are equal in strength, that is, are good conductors of electricity? No, because many substances in solutions or melts dissociate only to a small extent. Therefore, electrolytes are classified into strong, medium and weak forces.
What substances are strong electrolytes? Such substances in solutions or melts which are subjected to dissociation almost 100% of molecules regardless of the concentration of the solution. In the list of strong electrolytes includes the absolute most soluble alkalis, salts and some acids such as hydrochloric, bromide, iodide, nitrogen, etc.
What a difference electrolytes the average force? The fact that they dissociate to a much lesser extent (in the ions decay from 3% to 30% of the molecules). Classical representatives of such electrolyte – sulfuric and phosphoric acid.
And the behavior in solutions or melts of weak electrolytes? First, they dissociate to a very small extent (not more than 3% of the total number of molecules), and secondly, their dissociation is the worse and slower, the higher the concentration of the solution. Such electrolytes include, for example, ammonia (ammonium hydroxide), most organic and inorganic acids (including hydrofluoric – HF) and of course we are all familiar is water. Since only a very small fraction of its molecules splits into hydrogen ions and hydroxyl ions.
Remember that the degree of dissociation and, accordingly, the strength of the electrolyte are dependent on many factors: the nature of the electrolyte, solvent, temperature. Therefore, the division is somewhat arbitrary. It's one and the same substance may, under different circumstances, to be both a strong electrolyte and weak. To assess the strength of the electrolyte was introduced with a special value is the dissociation constant determined on the basis of the law of mass action. But it is applicable only to weak electrolytes strong electrolytes the law of mass action do not obey.

Advice 4: 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?
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.
Useful advice
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.
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