How to determine the conductivity of an electrolyte

A small amount of NaOH solids was added to each of the following solutions, and the smallest change in the conductivity of the solution was ( ).

a. Water is more variable because water is a weak electrolyte.

Strong electrolytes are added.

, the ion concentration varies greatly.

b. Hydrochloric acid is correct. When a small amount of caustic soda is added, it reacts with a small amount of hydrochloric acid, but sodium chloride is formed.

The part of the hydrochloric acid equivalent to the reaction is replaced with sodium chloride, so there is almost no change in ion concentration.

c. Acetic acid solution.

The answer is explained in the same way as a

D. NaCl solution.

In this way, the ion concentration in the solution directly increases the sodium hydroxide added.

The ion concentration increases and changes greatly.

So the least change above is b.

The strength of the conductivity is related to the concentration of the ion and the amount of charge carried by the ion, the greater the ion concentration, the stronger the conductivity, and the more charge the ion carries at the same concentration, the stronger the conductivity.

For example, 1mol per liter of hydrochloric acid is compared with sulfuric acid, which has a strong conductivity. Because there is a lot of charge.

Please understand it in a timely manner!! Good luck with your progress!!

d The conductivity is related to the ion concentration and the number of charges carried by the ions, and the conductivity does not change much, indicating that the ion concentration changes little.

If the volume is the same, the sulfuric acid is more conductive because the concentration of hydrogen ions is larger.

It is not possible to compare without stating the volume.

d Strong electrolyte solutions have the most ions.

The strength of the conductivity of a solution depends on the concentration of freely moving anions and cations in the solution and the amount of charge it carries. In this question, both anions and cations have only one charge, and the main consideration is the change in concentration.

a. Great changes. The ion concentration in pure water is very small, and sodium hydroxide is the electrolyte, which produces more ions after being added, and the conductivity is significantly enhanced.

b. Basically unchanged. HCl=H++Cl-, after adding NaOH solid, HCl+NaOH=NaCl+H2O, the amount of HCl consumed in the reaction is equal to the amount of sodium chloride generated, and the number of ionized ions from 1molHCl and 1molHCl is equal (NaCl=Na++Cl-), so the ion concentration is basically unchanged, and the conductivity is basically unchanged.

c. Great changes. Acetic acid is a weak electrolyte, the ionized ion concentration in the solution is small, after adding sodium hydroxide, the sodium acetate generated by the reaction is a strong electrolyte, the ion concentration increases more, and the conductivity is enhanced.

d. Slightly enhanced. A small amount of sodium hydroxide is added to the sodium chloride solution, and the two do not react, but the ions ionized by sodium hydroxide increase the ion concentration of the solution and enhance the conductivity.

In the end, the least changed is B

The amount of material used in light cannot be compared with the concentration of ions in the solution, so it is difficult to compare.

To determine whether a substance can conduct electricity, it is necessary to see whether the substance has freely moving ions in the molten state and whether there are ions in the solution state. Solid matter conducts electricity due to the presence of freely moving electrons like metallic elementals. Liquid conductivity is due to the presence of ions, such as sodium hydroxide solution or molten sodium hydroxide, and the electrolyte generally does not conduct electricity in the solid state, but conducts electricity in the molten state or in solution.

Metals are the most common type of conductors, such as aluminum, iron, copper, silver, etc., and most of the metals are conductors. The valence electrons in the outermost shell of a metal atom easily break free from the nucleus's beam.

To determine whether a substance can conduct electricity, it is actually to see if there is a freely moving charge (electron or ion) in the substance.

1. Metal. The outer electrons of a metal atom are affected by the nucleus.

The force of attraction is relatively small, and there is a potential difference.

, electrons can move directionally, so they are conductors.

All metals such as gold, silver, copper, iron, and alloys fall into this category.

2. Some covalent molecules, their atoms form covalent bonds.

Unsaturated, there are also remaining electrons that can move in a large range, and this substance will also become a conductor under certain conditions.

Graphite is typical, each carbon atom forms three bonds with other carbon atoms, leaving one free electron, which can move freely in the entire molecular plane (large bonds), so graphite conducts electricity in the direction of the molecular plane, but does not conduct electricity in the direction perpendicular to the molecular plane. There are also many semiconductors with this property.

3. Electrolyte solution.

The non-electrolyte solution does not conduct electricity, but in the electrolyte solution, the electrolyte ionizes positive and negative ions, which move directionally under the action of the electric potential difference, so they are conductors.

For example, salt water is a good conductor.

4. Liquid state (molten state.

ionic compounds.

In solid ionic compounds, both positive and negative ions are confined to the crystal lattice, and at most they do a small range of thermal movement, but cannot move in a large area, so they do not conduct electricity. However, when they are in the liquid state, the ions are free from the lattice bondage and can move directionally due to the potential difference, so they are conductors.

For example, solid salt does not conduct electricity, but salt in the molten state is a conductor.

5. Plasma.

When the original non-conductive substance, under the influence of high temperature, high voltage, strong radiation, etc., the outer electrons break free from the bondage, and the state of "positive ions + electrons" will be formed, similar to metal, this state is called plasma, because its electrons are excited by energy, so it is also conductive.

For example, air generally does not conduct electricity, but the air at high altitudes is controlled by the solar wind.

high-energy particle beams) to form a plasma, which becomes a conductor (the Earth's magnetic field can deflect the solar wind, but the polar regions have the weakest deflection of the solar wind, and the aurora is the photon emitted when the plasma returns to its ground state). Or under high pressure, the air is broken down (the suction of the positive electrode to the electrons and the suction of the negative electrode to the nucleus or positive ions are too great, and the two are torn apart and separated), so they are also conductive, and lightning is formed by the high pressure breaking through the air.

The substance is connected to a circuit, and the conductivity of the substance is judged by measuring the current in the circuit.

If it is elemental, the metal is a conductor, and the vicinity of the junction between metal and non-metal is a conductor.

Through the analysis of the structure of matter, it is seen whether there is a free-moving charge in the substance. For example, solid sodium chloride does not conduct electricity, because although there is a large number of charges, these charges cannot move freely, so they do not conduct electricity, and in the solution, they ionize freely to form sodium hydrate ions and chloride hydration ions, so they can conduct electricity.

This question needs to know what material you want to ask? If it is a metal, no need to ask, all of them are electrically conductive, which is determined by its structure, there are a large number of free electrons inside the metal, such as gold, silver, copper, iron, tin, auagcufesn, etc., of course, there are also some inert metals such as platinum pt, in addition, non-metallic carbon graphite c can also conduct electricity, inert metals themselves do not participate in the gain and loss of electrons, conductivity is no problem, in addition to a large number of electrolyte solutions can also conduct electricity, such as cuSO4 in copper-zinc galvanic batteries, ZNSO4 solutions can also conduct electricity.

Whether a substance can conduct electricity or not, you should first need to see what material it is made of, so that you should be able to know whether the substance can conduct electricity.

First of all, determine what kind of material the substance is, and judge whether it can conduct electricity according to whether the material is metal or non-metal.

You can do a slight rubbing, and put another hair to try to conduct electricity.

The method of determining the electrolyte is the compound that can conduct electricity in an aqueous solution or in the molten state, called an electrolyte.

Both electrolytes and non-electrolytes refer to chemical compounds (the premise of judgment) and are pure substances, with the difference that they can conduct electricity in an aqueous solution or in a melted state.

The premise of the conduction of a compound is that the cations and cations ionized by itself are simply rotten rather than the cations ionized after the reaction. Ammonia is not an electrolyte, but it can conduct electricity in water. The reason is that it reacts with water to form ammonia, which is an electrolyte.

Non-electrolyte: Compounds that do not conduct electricity in both aqueous solution and in the molten state are called non-electrolytes. Such as: sucrose, alcohol, etc.

Common Substance Categories:

1. Common electrolytes:

Acids: H2SO4, HCl, HNO3, H2SO3, H2CO3.

Bases: NaOH, NH3·H2O, Ca(OH)2.

Salts: NaCl, Kno3, BaSO4, AGCL.

Metal oxides: Cuo, CaO, MGO, Na2O.

Metal hydrides: NAH, CAH2.

Water: H2O.

2. Common non-electrolytes:

Non-metallic oxides: SO2, SO3, CO2.

Some non-metallic hydrides: NH3, PH3, ASH3.

Most of the organic matter is leaked: sucrose, alcohol, CH4.