 # Relationship between mass fraction For example, the solubility of a solution increases with the increase of temperature, and its mass fraction is p, so its mass fraction decreases after the increase of temperature. I know this. Isn't the mass fraction of solute divided by the mass of solution? Then, when the temperature rises, only the solubility, solute mass and solution mass have not changed (assuming that water does not evaporate), isn't its mass fraction unchanged? How did it get smaller? This friend on the second floor doesn't understand what I mean. Let's mention the specific topic. If you want to change the mass fraction of potassium nitrate saturated solution at a certain temperature, reducing the temperature is also a way. Once the temperature is reduced, the solubility of potassium nitrate solution increases, but no new solute is added, but the maximum solubility of the solution changes. Isn't this process that the solute quality and solution quality haven't changed? How did the mass fraction change? It's not what the friend on the second floor said

## Relationship between mass fraction For example, the solubility of a solution increases with the increase of temperature, and its mass fraction is p, so its mass fraction decreases after the increase of temperature. I know this. Isn't the mass fraction of solute divided by the mass of solution? Then, when the temperature rises, only the solubility, solute mass and solution mass have not changed (assuming that water does not evaporate), isn't its mass fraction unchanged? How did it get smaller? This friend on the second floor doesn't understand what I mean. Let's mention the specific topic. If you want to change the mass fraction of potassium nitrate saturated solution at a certain temperature, reducing the temperature is also a way. Once the temperature is reduced, the solubility of potassium nitrate solution increases, but no new solute is added, but the maximum solubility of the solution changes. Isn't this process that the solute quality and solution quality haven't changed? How did the mass fraction change? It's not what the friend on the second floor said

Obviously, you don't understand the concept of solubility. (solubility, the mass dissolved when a solid substance reaches saturation in 100g solvent at a certain temperature) the solubility increases, that is, the solute mass increases, the solution mass also increases, and obviously the mass fraction decreases. For example, the solubility of a substance at 10 degrees is 2

### At a certain temperature, the solubility of a substance is a g, and the mass fraction of solute in the saturated solution is B%, then the size relationship between a and B is?

a>b
Using the data substitution method,
Suppose the solubility is 10 grams
Then the mass fraction of solute in saturated solution = 10 / 110 = 9.1%
Of course, other data can also be substituted, and the results are the same
It can even carry out mathematical reasoning, which is not necessary

### Why is it that the higher the solubility, the greater the mass fraction of the solute in the saturated solution

According to the calculation formula, mass fraction = = s / (s + 100)
From the above formula, the higher the solubility (s), the greater the mass fraction of the solute in the saturated solution

a

### When the solubility of a solute is s g at a certain temperature, the mass fraction of solute in saturated solution at that temperature () A. Greater than S% B. Equal to S% C. Less than S% D. Unable to judge

Solubility is the saturated solution of S. according to the concept of solubility, s is the mass of solute dissolved when saturation is reached in 100g solvent. Assuming that the solute mass fraction of saturated solution is a%, it means that 100g saturated solution contains Ag solute, that is, some solvents in this solution are less than 100g, the more solvents are at the same temperature, the more solutes are dissolved, so the value of S is greater than the value of A
So choose C

### When the mass fraction of solute in KNO3 saturated solution is 20% at a certain temperature, the solubility of KNO3 at this temperature is 25g

At this temperature, the solubility of KNO 3 is XG
x/(x+100) = 20%
The solution is x = 25g
Answer: the solubility of KNO3 at this temperature is 25g
If you do it yourself, please give points