## It is known that the mass fraction of nitrogen in the solid mixture of NH4NO3 and KH2PO4 is 28%, so the mass fraction of KH2PO4 in the mixture is () A. 20% B. 25% C. 85% D. 80%

If the mass of the mixture is m, then the mass of NH4NO3 is X. according to the fact that the mass of N element in NH4NO3 is equal to the mass of N element in the mixture,

Then M × 28%═X × fourteen × two

fourteen × 2+1 × 4+16 × three × 100%

Solution x

M═0.8

Then the mass fraction of NH4NO3 in the mixture is X

M × 100%═80%，

The mass fraction of KH2PO4 is 1-80% - 20%,

So choose a

### It is known that the mass fraction of nitrogen in the solid mixture of NH4NO3 and KH2PO4 is 28%, so the mass fraction of KH2PO4 in the mixture is () A. 20% B. 25% C. 85% D. 80%

If the mass of the mixture is m, then the mass of NH4NO3 is X. according to the fact that the mass of N element in NH4NO3 is equal to the mass of N element in the mixture,

Then M × 28%═X × fourteen × two

fourteen × 2+1 × 4+16 × three × 100%

Solution x

M═0.8

Then the mass fraction of NH4NO3 in the mixture is X

M × 100%═80%，

The mass fraction of KH2PO4 is 1-80% - 20%,

So choose a

### It is known that the mass fraction of nitrogen in the solid mixture of NH4NO3 and KH2PO4 is 28%, so the mass fraction of KH2PO4 in the mixture is () A. 20% B. 25% C. 85% D. 80%

If the mass of the mixture is m, then the mass of NH4NO3 is X. according to the fact that the mass of N element in NH4NO3 is equal to the mass of N element in the mixture,

Then M × 28%═X × fourteen × two

fourteen × 2+1 × 4+16 × three × 100%

Solution x

M═0.8

Then the mass fraction of NH4NO3 in the mixture is X

M × 100%═80%，

The mass fraction of KH2PO4 is 1-80% - 20%,

So choose a

Then M × 28%═X × fourteen × two

fourteen × 2+1 × 4+16 × three × 100%

Solution x

M═0.8

Then the mass fraction of NH4NO3 in the mixture is X

M × 100%═80%，

The mass fraction of KH2PO4 is 1-80% - 20%,

So choose a

### Find the mass fraction of elements in the mixture The solid mixture of sodium carbonate and sodium sulfate is 13.1g in total. After sufficient barium chloride solution is added, it is fully reacted. It is measured that 22.2g white solid is generated after the reaction, and the mass fraction of sodium element in the original mixture is calculated

Let the mass of sodium element in the original mixture be X

Na2CO3+BaCl2=BaCO3↓+2NaCl

106 197

Na2SO4+BaCl2=BaSO4↓+2NaCl

152 233

It is easy to know that the mass difference of the solid before and after the reaction is the difference between the mass of Ba and Na

∴m(Ba)-m(Na)=22.2g-13.1g=9.1g

Ba~2Na

137 46

137/m(Ba)=46/x

m(Ba)-x=9.1g

x=4.6g

The mass fraction of sodium in the original mixture Na% = 4.6g/13.1g ×% ≈35.11%

Answer: the mass fraction of sodium in the original mixture is 35.11%

### It is known that the solubility of KNO3 is 31.6 g at 20 ℃. What are the solute and solvent in a KNO3 solution with a mass fraction of 10% of 100g solute? I don't quite understand this question

In KNO3 solution with mass fraction of 100g solute of 10%, the solute is 100g * 10% = 10g, and the solvent is 100g-10g = 90g

90g * 31.6g / 100g = 28.44g > 10g, so it is the unsaturated solution of KNO3 at 20 ℃