Junior Chemistry Water electrolysis, chemical equations for water electrolysis

a When water electrolyzes to produce hydrogen and oxygen, it is the conversion of electrical energy into chemical energy, while refrigeration is caused by the freezing of water and the absorption of heat.

c The composition of the refrigerant is still ice and water, and its chemical composition is water molecules, so the chemical properties are the same.

Pure liquid water is filled with strong alkalis (such as sodium hydroxide or potassium hydroxide) or strong acids (such as sulfuric acid) to increase electrical conductivity at concentrations of 5% to 10%, the higher the concentration, the faster the electrolysis, otherwise hydrogen and oxygen will not be generated after the electricity is applied.

It should be noted that although the addition of table salt (mainly sodium chloride) can also increase electrical conductivity, the products are sodium hydroxide, hydrogen and chlorine!! Stay safe!!

Water and ice are not the same.

Ice is solid and does not ionize out h+ and 0h-

So electrolytic ice will not have hydrogen and oxygen.

If LZ chooses A, then why not C?

Water electrolysis is angry, but ice is not

For electrolysis, the reactant condition is water instead of ice.

Since it is a refrigerant, it is naturally a mixture, and the main ingredients are water and ice, okay?

a.Water electrolysis breaks down into hydrogen and oxygen. Ice can't. b.According to the chemical reaction, the type of elements remains unchanged before and after the chemical reaction, and hydrogen and oxygen are pollution-free. c.The refrigerant is a mixture of ice and water, so it has different chemical properties from water.

I guess it's because ice and water are different! Ice is pure, water has to be distilled! But you still have to ask the teacher!

Electrolysis of water produces hydrogen and oxygen, but I have never heard of electrolytic ice.

Electrolysis of waterChemical equations：2h2o=2h2↑+o2↑。

Electrolyzed water refers to the water generated after the tap water is filtered, sterilized, adsorbed and purified to meet the standard, and after the electrolysis of the filial piety fiber with diaphragm.

There are two types. One is alkaline electrolyzed water with health care functions for drinking; Qiaolu.

The other is acidic electrolyzed water for external use with disinfection and sterilization effects.

Alkaline electrolyzed water is also known as alkaline ionized water, anion water, and alkaline calcium ionized water.

Electrolyzed water is currently recognized as the safest and most advanced water in the world's advanced countries, and it is also the only water that fully complies with the World Health Organization.

Erection of the six standards of good water".

The chemical equation for electrolytic water is: 2H2O===2H2 +O2 (energized). It means that hydrogen and oxygen are produced when water is electrified. Electrolyzed water generally refers to the product produced by the electrolysis of water containing salts (such as sodium chloride).

The chemical equation for electrolysis of water is: 2H2O==2H2 +O2. (Note: Under the condition of energizing), hydrogen is precipitated from the negative electrode, and oxygen is precipitated from the positive electrode, and the volume ratio of hydrogen to oxygen is 2:1.

Extended Information - Chemical Equations

A chemical equation, also known as a chemical reaction equation, is a formula that uses a chemical formula to express the chemical reaction of a substance. Chemical equations reflect objective facts. Therefore, there are two principles to be observed in writing chemical equations:

First, the imitation of the group posture must be based on objective facts; The second is to abide by the law of conservation of mass.

The chemical equation not only indicates the reactants, products, and reaction conditions. At the same time, the stoichiometric number represents the quantitative relationship between the reactants and the product substances, and the mass relationship between the substances can also be expressed through the relative molecular mass or relative atomic mass, that is, the mass ratio between the substances. For gas reactants and products, the volume ratio can also be obtained directly from the stoichiometric number.

Reaction conditions

Thermochemical equations or Sunwrite reaction conditions. The general ones are marked with δ above the equal sign. The trim factor can also be a fraction or a fraction of each other.

The reaction that can be carried out at room temperature and pressure does not need to write the conditions; However, if there are specific conditions for the experiments in the questions, they are always marked with specific conditions.

When a single condition is reflected, the condition is always written above; If there are two or more conditions, what cannot be written above is written below; When there is both a catalyst and other reaction conditions, the catalyst is always written on it. It is a reversible reaction and is always indicated by a double arrow.

Arrows and equal signs

In the literature in the professional field, the arrow "" " is used to connect reactants and products in the equations of both inorganic and organic reactions. However, in the teaching of middle schools in most provinces and cities, it is still recommended to use equal signs when writing the equations of inorganic chemical reactions according to the textbooks, so as to better represent the meaning of "generation" and "conservation of mass" in the reaction.

In 2013, the equations of inorganic reactions in middle school were all connected by equal signs, and the organic reactions were all connected by arrows, and all reversible reactions were represented by reversible symbols.

Water electrolysis. Phenomenon: There are bubbles in the test tube, and the gas ratio produced by the test tube connected to the positive electrode (oxygen) and negative electrode (hydrogen) of the power supply is 1:2 (memorize the formula: hydrogen dioxygen one, positive oxygen and yin hydrogen).

However, in general, the volume ratio of hydrogen to oxygen is generally greater than 2:1 for two reasons

1.Solubility of hydrogen and oxygen.

Hydrogen is insoluble in water, oxygen is not soluble in water (1L of water is 30ml of oxygen) but a small part of oxygen is soluble in water, with a ratio greater than 2:1

2.Electrode oxidation consumes a portion of oxygen.

Conclusion: Water is composed of two elements, hydrogen and oxygen, and the molecular formula of water can be inferred from the ratio of gases produced.

The water electrolysis experiment is an experiment in which an electric current is passed into water to split water into hydrogen and oxygen. The principle is based on the chemical reaction of electric decomposition.

In a water electrolysis experiment, two electrodes (usually platinum or stainless steel) are inserted into the water, one connected to the positive electrode (anode) and the other electrode connected to the negative electrode (cathode). When an electric current is passed through water, the following two reactions occur

1.At the anode (cathode): the oxide ions (oh-) in the water accept electrons, an oxidation reaction occurs, and oxygen (O2) is generated in the standby brigade

2h2o(l) o2(g) +4h+(aq) +4e-

2.At the cathode (negative electrode): hydrogen ions (H+) in water release electrons and a reduction reaction takes place to generate hydrogen gas (H2).

4h+(aq) +4e- 2h2(g)

Through these two reactions, water molecules are broken down into oxygen and hydrogen, with oxygen produced at the anode and hydrogen at the cathode.

It should be noted that the water used in the electrolyzed water experiment must be pure water to avoid the interference of impurities in imitation of simple stools. In addition, the hydrogen and oxygen produced by the water electrolysis experiment are flammable, and safety measures need to be taken to avoid the risk of fire or **.

Around 2000, when I was in the first year of junior high school, chemistry talked about the preparation of oxygen, and I thought that electrolysis of water would have hydrogen and oxygen, so I tried it myself, and I did water electrolysis experiments myself, and I also learned the knowledge of some electrode reactions, which used DC6V (DC means DC) and DC280V voltage at that time.

Precautions]:

To use DC voltage;

If it exceeds 60V, it is not safe, please take precautions, including but not limited to: insulating gloves, goggles, earplugs, anti-arc face screen, arc protective clothing, anti-arc gloves;

The power supply needs to have a fuse and a switch that can trip;

To use relatively clean water, purified water is recommended;

It is recommended to use a graphite electrode (use a dry battery positive carbon rod to keep it clean).

Schematic diagram] <>

Process] I got a wide-mouth canned bottle, filled half a bottle of tap water, started with 6V, and directly stripped 1cm of copper wire as an electrode, and the result was that there were almost no bubbles on the positive electrode, and the hydrogen bubbles on the negative electrode were also very small (below the estimated bubble diameter), and it could not even be called bubbles, it was a very small bubble; Soon (less than half an hour) the water turned blue, the copper wire of the positive electrode was broken, and there was a precipitate at the bottom of the bottle, and the water with the precipitate was boiled, and the precipitate turned black. Then I tried to use aluminum wire as an electrode, which was also aluminum hydroxide; Iron has also tried the same, first green and then reddish-brown flocculents. In the end, the battery cell and carbon rod were used, and there were bubbles at the positive electrode, oxygen.

Because the bubbles are too small and too few, I adjust the voltage, and the maximum can only be adjusted to 9V, and the bubbles have increased, which is not obvious. So I used 4 diodes and a 400V 10UF capacitor to make a bridge rectifier filter circuit, and the measured voltage of the multimeter was about DC280V (never short circuit or touch it by hand!!). After carefully energizing, the bubbles on the positive and negative carbon rods bubbled up a lot, just like when the water was just boiling, and the effect was very good, and the effect I wanted was achieved.

After observing for a few minutes, the power is cut off and things are packed. As a rural baby, I didn't know who to share the joy and questions in my heart at that time, and later told my father Jane, who had studied high school, that he couldn't explain some phenomena and principles clearly. Later, I saw a "Formula Theorem for Middle School Students", which was slightly mentioned in the electrolytic reaction part of chemistry, which was a partial solution.

At that time, DC6V was used to electrolyze salt water, and the smell of chlorine (be careful, chlorine is harmful to the human body), I can't forget it for a long time, and the bottle is full of pale green chlorine.

Summary] The recommended voltage is 24 or 48V (the voltage is too low to see obvious bubbles), and the current is about 1A. Pure water has a large resistance, and the current is very small when it actually bubbles. In fact, the dry battery is thrown into the water, and it also has this reaction, but the bubbles are too small to see.

Batteries need to be disposed of properly and should not be thrown into drinking water or soil, otherwise harmful substances will enter the soil or drinking water and harm future generations.

The chemical equation for electrolysis of water: 2H2O=2H2 Stool Plexus+O2.

Electrolyzed water refers to the water generated after tap water is filtered, sterilized, adsorbed to make it purified to meet the standard, and electrolyzed by a diaphragm.

There are two types. One is alkaline electrolyzed water with health care functions for drinking;

The other is an acidic electric defense for external use with disinfection and sterilization effects.

Alkaline electrolyzed water is also known as alkaline ionized water, anion water, and alkaline calcium ionized water.

Electrolyzed water is currently recognized as the safest and most advanced water in the world's advanced countries, and it is also the only water that fully meets the "Six Standards of Good Water" of the World Sanitation Zaozao Sakura Organization.

The chemical equation for water electrolysis: 2H2O = energized = 2H2 (gas) + O2 (gas).

2h o energized world slip vertical =

o₂↑+2h₂↑

Direct current is used to electrolyze water, and sodium hydroxide can be added to the water to enhance the conductivity of water.

Water can be decomposed into hydrogen and oxygen under the action of direct current. When electric sparks pass through hydrogen and oxygen mixed with gas, they are synthesized into water. Both experiments show that water is composed of two elements, hydrogen and oxygen, and from the experimental results, it can also be known that their volume ratio is 2 1.

As early as 1800 wWilliam Nicholson had produced oxygen and hydrogen from electrolysis of water, but it was not industrialized until 1913.

Composition and products of water electrolysis

A single electrolyzer for water electrolysis consists of a tank, anode, cathode, and separator. The tank material is mostly steel, the anode is nickel-plated steel plate, the cathode is carbon steel plate, and the separator material is polypropylene, porous nickel plate, potassium titanate fiber, etc. Water electrolysis uses alkaline aqueous solution as the electrolyte, and after direct current, hydrogen is precipitated at the cathode and oxygen is precipitated at the anode.

Hydrogen and oxygen, separated by a diaphragm, are separately drained with catheters.

The hydrogen produced by electrolysis is mainly used for the synthesis of ammonia, hardening grease, synthetic hydrochloric acid, etc. The by-product oxygen is mainly used in hydrogen and oxygen blowpipes, oxy-acetylene blowpipes, steelmaking, etc. The use of hydrogen and oxygen at the same time can reduce the production cost of water electrolysis.

The above content refers to Encyclopedia - Water Electrolysis.