What is the difference between urea 85 and 105

There is no such thing.

Current national standards related to urea.

GB 2440-2001 Urea 2002-01-01 implemented, instead of GB 2440-1991, GB T 13257-1991

GB T 2602-2002 Urea method for the determination of intermediate cresol content of phenolic products 2003-04-01 was implemented to replace GB T 2602-1981

GB T 2947-2002 Determination of free water content in urea and ammonium nitrate Karl Fischer method 2003-04-01 was implemented instead of GB T 2947-1982

Determination method of urea in swimming water of GB t 2001-01-01 was implemented.

GB 18560-2001 Occupational exposure limits for urea in the air in workshops 2002-05-01 implemented.

GB T 10476-2004 Urea high-pressure condenser technical conditions 2004-12-01 implementation, instead of GB 10476-1989

GB T 9843-2004 Urea high-pressure scrubber technical conditions 2004-12-01 implementation, instead of GB 9843-1988

GB T 9842-2004 Technical conditions for urea synthesis tower 2004-12-01 implementation, instead of GB 9842-1988

GB T 8622-2006 Determination of urease activity in soybean products for feed 2006-09-01 Implemented on 2006-09-01 instead of GB T 8622-1988

GB T 696-2008 chemical reagent urea (urea) 2008-11-01 implemented, instead of GB T 696-1994

Urea, also known as carbamide, is an organic compound composed of carbon, nitrogen, oxygen, and hydrogen, also known as urea, which is a white crystal. One of the simplest organic compounds. Diamide of carbonated with the molecular formula H2NCONH2 (Co(NH2)2) and molecular weight 60.

The main nitrogenous end product of protein metabolism in mammals and some fish. It is also the nitrogen fertilizer with the highest nitrogen content at present. As a neutral fertilizer, urea is suitable for a wide range of soils and plants.

It is easy to preserve, easy to use, and has little damage to the soil, and is a chemical nitrogen fertilizer that is currently used in large quantities. Ammonia and carbon dioxide are used in industry to synthesize urea under certain conditions.

1. The focal length is different.

2. The aperture is different.

3,15-85 for APS series Canon SLR cameras24-105 for both APS series Canon SLR cameras and full-frame cameras4,** and weight are not the same.

5. The lens combination structure is also different.

24-105 is a red circle, the picture quality is better, it is worth buying, and the upper full set continues to be used; 15-85 can only be used on the C frame, the equivalent focal length 24 wide angle is basically not used a few times (you can use splicing to solve the wide angle problem), the non-constant aperture is not cool to use, how to choose you should know, right?

The price is about the same, not wordy.

The biggest difference is that 24-105 is a full head that can be used in the future, and 15-85 is the opposite.

24-105 Half width is missing, 15-85 width will be larger.

24-105 Red circle.

The 15 85 is one of the best lenses in half.

The 24 105 is a full set of entry shots.

The 24-105 optical quality and workmanship are better than the 15-85, and the f4 constant aperture is still much more useful than the aperture.

If you use the full pair, it depends on whether you use the full pair or truncate it, which is not well received.

Urea is also known as carbodiamine, carbaamide, urea. It is an organic compound composed of carbon, nitrogen, oxygen, and hydrogen, also known as urea (homonym with urine). Its chemical formula is Con2H4, (NH2)2CO or CN2H4O, and the international generic drug name is Carbamide.

The appearance is white crystals or powder. It is a product of animal protein metabolism and is commonly used as a nitrogen fertilizer for plants. Urea is synthesized in the liver and is a nitrogenous metabolite excreted by mammals.

This metabolic process is called the urea cycle. Urea is the first organic compound obtained by the artificial synthesis of inorganic substances. The vitalism has since been overthrown.

Urea can also be classified as a nitrogen fertilizer with a nitrogen content of 46% or more.

To put it simply, it is a kind of fertilizer applied to vegetables and fruits to promote the growth of branches and leaves, which is equal to one of the nutrients required by similar people.

Allantoin is a complex of urea, but the use is very different, the former can be used directly or as an additive, it can promote cell growth, speed up wound healing, widely used in medical treatment; Urea is the main way of biological metabolism and excretion of nitrogen-containing wastes, which is toxic and mainly used for agricultural organic nitrogen fertilizer.

Urea is weakly alkaline and is close to neutral in aqueous solution.

Chemical properties of urea:

It can react with acids to form salts. There is hydrolysis. At high temperatures, condensation reactions can be carried out to produce biuret, triuret and cyanuric acid.

Heated to 160 degrees to decompose, ammonia gas is produced and becomes isocyanic acid at the same time. Because it contains this substance in human urine, it is named urea. The nitrogen content of urea (N) is 46%, which is the highest nitrogen content among solid nitrogen fertilizers.

Urea can be hydrolyzed to produce ammonia and carbon dioxide under the action of acids, alkalis and enzymes (acids and alkalis need to be heated). Urea is easily soluble in water, 105 grams can be dissolved in 100 ml of water at 20, and the aqueous solution is neutral. There are two types of urea products.

Crystalline urea is white needle-like or prismatic crystal, strong hygroscopicity, agglomerates after moisture absorption, and the moisture absorption rate is 12 times faster than that of granular urea. [2] Granular urea is a translucent particle with a particle size of 1 2 mm, which has a smooth appearance and significantly improved hygroscopicity. At 20 o'clock, the critical moisture absorption point is 80% of the relative humidity, but at 30 o'clock, the critical moisture absorption point drops, so urea should be avoided in the humid climate of midsummer.

When hydrophobic substances such as paraffin wax are added to urea production, its hygroscopicity is greatly reduced.

Preparation method of urea:

Method 1: Ammonium carbamate is synthesized with carbon dioxide and ammonia at high temperature and high pressure, and after decomposition, absorption and conversion, crystallization, separation and drying.

Method 2: The preparation method is to mix the purified ammonia and carbon dioxide massage Erbi into the synthesis tower, the pressure in the tower is MPA, the temperature is 180 200, the residence time of the reaction material is 25 40min, the urea solution containing excess ammonia and ammonium carbamate is obtained, and the urea solution after separating ammonia and ammonium carbamate is evaporated to the above after reducing pressure and cooling, and then granulated in the granulation tower to obtain the finished urea product.

Method 3: Urea is the final product of protein metabolism in mammals. In 1922, the industrial production of urea from ammonia and carbon dioxide was realized in Germany. Ammonia reacts with carbon dioxide to form carbamate amine, which is then dehydrated to produce urea.

Industrial method: production method: liquid ammonia and carbon dioxide are used as raw materials in industry, and urea is directly synthesized under high temperature and high pressure conditions, and the chemical reaction is as follows

2nh3+co2→nh2coonh4→co(nh2)2+h2o

Hello: In the environment of normal temperature and pressure, urea is neutral; The aqueous solution of urea is weakly alkaline.

Urea, also known as carbamide, is a white crystal. One of the simplest organic compounds. Diamide of carbonic acid with the molecular formula H2NCONH2(CO(NH2)2) and the chemical formula:

Co(NH2)2, relative molecular weight, CO(NH2)2 colorless or white needle-like or rod-like crystals, industrial or agricultural products are white slightly reddish solid particles, odorless and tasteless. The nitrogen content is about. Density.

Melting point. Soluble in water and alcohol, insoluble in ether and chloroform. It is weakly alkaline.

The torque of the transmission is not the same, one is 1050Nm, the other is 850Nm, the transmission speed ratio, gear, shell size, and total length are all different!

50mm is equivalent to the angle of view of the human eye, the larger the number (such as ), the telescope effect, the smaller the angle of view, if you want to play with it, 18-85 or 18-138 is enough.

The longer the focal length, the closer the distant scene will be. You can use 85 or less for people and 85 or more for scenery.

55mm, 105mm, 135mm, etc. are the focal length of the lens. The smaller the number, the closer it is to a wide angle. The higher the number, the closer it is to a long focal length.

Generally, taking pictures mainly depends on what we shoot. If the lens does not change, it is in focus. If the lens is variable, it is a zoom lens.

If we are traveling to shoot a landscape, it is best to choose a zoom lens 28 to 280. If you are professional, prepare a few more shots. The 55-280 telephoto lens can shoot people or objects 100 meters away, and the 55mm medium lens is dedicated to shooting people and objects in front of you, and you can also shoot landscapes.

The 18-55 wide-angle lens or macro lens is dedicated to taking panoramic views of tall buildings in front of you or close-ups of flowers.

As a neutral fertilizer, urea is suitable for a wide range of soils and plants. It is easy to preserve, easy to use, has little damage to the soil, and is a chemical nitrogen fertilizer with a large amount of use. Ammonia and carbon dioxide are used in industry to synthesize urea under certain conditions.

CO(NH2)2 urea is a common name for carbon amide, also known as urea, which is a peramide of carbonated acid with the structural formula H2N-Co-NH2

Co(NH2)2C and O are double-bonded and the two HN2s are connected to C.