Given a mass, how much mass of this solid will dissolve in w

In summary, the question asks for the mass of Fe(OH)3 that will dissolve in 3.84 L of water, given a Ksp of 2.8E-39. Using the Ksp equation and solving for x, the concentration of Fe(OH)3 is found to be 1.009E-10 mol/L. Multiplying this by the volume of water yields a total of 4.14E-8 grams, which is the mass of Fe(OH)3 that will dissolve. The original mass given in the question is not used in the calculation.
  • #1
Revengeance
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Homework Statement


If 0.025 g of Fe(OH)3 is added to 3.84 L of water, what mass will dissolve? Ksp is 2.8E-39.

Homework Equations


Ksp = [x][x]
n= m/M

The Attempt at a Solution


I believe in this question that the starting mass is deemed irrelevant (although now i am starting to believe that is required to do something)

So, Fe(OH)3 = Fe + 3OH, this means that our Ksp equation will be

(x)(3x)^3 = 2.8E-39
So we can simplify to 27x^4 = 2.8E-39, solve for x to get the concentration, which will yield 1.009E-10 mol/L.Now multiply by volume:
1.009E-10 mol/L * 3.84 L = 3.875E-10 mol * 106.8670 g/mol = 4.14E-8 grams. This is what i am getting and this incorrect. Can someone explain why, and also can someone explain if we have to use the starting mass somehow.
 
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  • #2
Think about concentration of OH-.
 
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  • #3
Borek said:
Think about concentration of OH-.
ok so with the mass of the Fe(OH)3 we are given we can find the moles of it and turn it into concentration, is this what you are referring to?
 
  • #4
Revengeance said:
ok so with the mass of the Fe(OH)3 we are given we can find the moles of it and turn it into concentration, is this what you are referring to?

Yes, just remember to use the mass that you calculated from Ksp, not the original one given in the question.
 

FAQ: Given a mass, how much mass of this solid will dissolve in w

1. What is the definition of solubility?

The solubility of a substance is the maximum amount of that substance that can dissolve in a given amount of solvent at a specific temperature and pressure.

2. How is solubility determined experimentally?

Solubility is determined by adding a known mass of a solid to a fixed volume of solvent and measuring the amount of solid that dissolves. The solubility is then calculated by dividing the mass of the dissolved solid by the mass of the original solid and multiplying by 100.

3. Why does temperature affect the solubility of a substance?

The solubility of a substance generally increases with increasing temperature. This is because at higher temperatures, the molecules of the solvent have more kinetic energy, allowing them to move around more freely and interact with the molecules of the solute, making it easier for the solute to dissolve.

4. What factors can affect the solubility of a substance?

The solubility of a substance can be affected by temperature, pressure, and the chemical nature of the solute and solvent. For example, polar substances tend to be more soluble in polar solvents, while nonpolar substances are more soluble in nonpolar solvents.

5. How can the solubility of a substance be used in practical applications?

The knowledge of a substance's solubility can be used in various industries, such as pharmaceuticals, agriculture, and manufacturing. For example, in pharmaceuticals, the solubility of a drug can affect its effectiveness and absorption in the body. In agriculture, the solubility of fertilizers can affect their availability to plants. In manufacturing, the solubility of materials can impact the efficiency of production processes.

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