Physical nature

The urea is easily dissolved in water, and 105 grams is dissolved in 100 ml of water at 20 ° C. The aqueous solution is neutral. There are two kinds of urea products. Crystal urea is white or bonded crystal, with strong hygroscopicity. After moisture absorption, the moisture absorption speed is 12 times faster than granular urea. [1] granular urea is a translucent particle with a particle size of 1 to 2 mm. The appearance is bright and the hygroscopicity has improved significantly. At 20 ° C, the critical humidity point is 80%relative humidity, but at 30 ° C, the critical humidification point is reduced to 72.5%. Therefore, urea should be avoided under the humid climate in summer. The hydrophobic substance such as paraffin is added to the production of urea, and its hygroscopicity has been greatly reduced.

Chemistry

Urea can generate salt with acid. Hydrolysis. Convergence can be performed at high temperatures to generate two -crickets, tannal and triocyanic acid. Heating to 160 ° C decomposes, producing ammonia gas also becomes different cyanocyanic acid. Because this substance is contained in human urine, it is named for urea. Urea contains 46%of nitrogen (n), which is the highest nitrogen content in solid nitrogen fertilizers.

Urea can hydrolyze ammonia and carbon dioxide in the action of acid, alkali, and enzymes.

If the heat is unstable, heating to 150 ~ 160 ℃ will shrink the two crickets. Copper sulfate and dichotoma are purple, which can be used to identify urea. [1] If it is quickly heated, the decarcation and the triumotrophic acid cyanocyanic acid is gathered into a six -dollar cycle. [Mechanism: First ammonia to generate isocyanic acid (hn = c = o), repeatedly gather. .

The effect of acetyl chlorine or acetic anhydride can generate acetylcin and acetyl.

Under the action of ethanol sodium, a propylene glycodic acid (also known as Barbaric acid, because it has a certain acidity) under the action of sodium ethanol.

Under the action of alkaline catalysts such as ammonia water, it can react with formaldehyde and shrink into a rigiddehyde resin.

Activation with hydraulic pheasant.