KNO3 is an important chemical product. The following are the main steps of a patented KNO3 preparation method: (1) In reaction I, CaSO4 and NH4HCO3

(1) In reaction Ⅰ, the ratio of the amounts of CaSO4 and NH4HCO3 is 1:2. From the flow question, we can know that CaCO3, (NH4) 2SO4 and CO2 are generated. From the conservation of mass, we can know that the equation of the reaction is CaSO4+2NH4HCO3=CaCO3↓+(NH4)2SO4+H2O+CO2↑,

So the answer is: CaSO4+2NH4HCO3=CaCO3↓+(NH4)2SO4+H2O+CO2↑;

< p>(2) (NH4)2SO4 is added to KCl under dry and heated conditions to generate easily decomposed ammonium chloride. When heated, ammonium chloride decomposes to generate hydrogen chloride and ammonia. When the temperature decreases, ammonium chloride is generated again. , in this way, ammonium chloride can be separated and potassium sulfate can be obtained, and the reaction rate can be accelerated; the method of separating CaSO4 from the mixture obtained in reaction IV is to filter while it is hot. The purpose of filtering while it is hot is to prevent KNO3 from crystallizing and improve the concentration of KNO3. Yield,

So the answer is: separate NH4Cl and K2SO4 to speed up the chemical reaction rate; prevent KNO3 from crystallizing and increase the yield of KNO3;

(3) Check the K2SO4 obtained from reaction II Whether it is mixed with KCl, potassium sulfate should be completely converted into barium sulfate precipitate when barium nitrate is added first, so as not to interfere with the test of chloride ions, and then silver nitrate is added to test potassium chloride. The operation method is to add Ba (NO3) 2 solution until it no longer Precipitation occurs, let it stand, and add AgNO3 solution dropwise to the upper supernatant. If there is precipitation, it means that K2SO4 is mixed with KCl.

So the answer is: add Ba(NO3)2 solution until no more precipitation occurs. Precipitate, let it stand, and add AgNO3 solution dropwise to the upper supernatant. If there is precipitation, it means that K2SO4 is mixed with KCl;

(4) In the entire process, the recyclable substances except (NH4) In addition to 2SO4, there are CaSO4 and KNO3, so the answer is: CaSO4, KNO3;

(5) B is a three-atom molecule. B reacts with O2 to produce 1 volume of gas A and 2 volumes of reddish-brown gas C. C should be NO2, and the yellow-green gas should be Cl2.

Then B contains N elements and Cl elements. The reaction equation should be 2B+O2=Cl2+2NO2. It can be seen that the molecular formula of B is NOCl, < /p>

So the answer is: NOCl.