How do you determine the percent composition by mass of a 100 g K2SO4 solution containing a 20-g solute. What is the mole percent composition of the solute, assuming that the solution consists of 100 g water and 20 g of K2S04?

For percent composition of K2S04, I got 44.9 % K, 18.4 % S, and 36.7 % O, but I'm not sure if that's right. I have no idea how to determine the mole percent composition, though. If anyone can help me with this problem, I'll truly appreciate it!

For mole composition, you would convert each to moles and then determine the percent of each to the total.

Thank you for the help : ) I just have 2 questions:

Was the percent composition for K2SO4 that I calculated correct? Also, would I convert the 20 g of K2SO4 to moles, and then find the individual moles of each element in that compound? Thanks again for the help!

For percent composition K, S, and O, your numbers are correct; however, I don't think that is the answer to the question. As I read the question, you have 20 g K2SO4 in 100 g solution. The question is what is the percent K2SO4. That is 20%.

To determine the percent composition by mass of a substance within a solution, you need to know the mass of the solute (the substance being dissolved) and the total mass of the solution. In this case, you are given that the solute (K2SO4) has a mass of 20 g and the total solution has a mass of 100 g.

To find the percent composition by mass of each element in K2SO4, first find the molar mass of K2SO4 (potassium sulfate). The molar mass can be calculated by adding up the atomic masses of all the atoms in the molecule. In this case, the molar mass of K2SO4 is:

2(K) + 1(S) + 4(O) = 39.10 g/mol + 32.07 g/mol + (4 * 16.00 g/mol) = 174.27 g/mol

Now we can calculate the percent composition of each element in K2SO4:

Percent Composition of K (Potassium):
(2 * 39.10 g/mol) / 174.27 g/mol * 100 = 44.9 %

Percent Composition of S (Sulfur):
(32.07 g/mol) / 174.27 g/mol * 100 = 18.4 %

Percent Composition of O (Oxygen):
(4 * 16.00 g/mol) / 174.27 g/mol * 100 = 36.7 %

So, your percent composition seems correct: 44.9% K, 18.4% S, and 36.7% O in K2SO4.

To determine the mole percent composition, you need to convert the mass of each element to moles. Then calculate the mole percent of each element by dividing its mol quantity by the total moles and multiplying by 100.

First, calculate the number of moles of K2SO4 by dividing the mass by its molar mass:

Moles of K2SO4 = 20 g / 174.27 g/mol = 0.1145 mol

The total moles in the solution can be calculated by dividing the mass of water (100 g) by its molar mass (18.015 g/mol). This gives:

Moles of Water = 100 g / 18.015 g/mol = 5.55 mol

Now, we can calculate the mole percent composition for each element:

Mole Percent Composition of K (Potassium):
(2 * 0.1145 mol) / (0.1145 mol + 5.55 mol) * 100 = 2.02 %

Mole Percent Composition of S (Sulfur):
(1 * 0.1145 mol) / (0.1145 mol + 5.55 mol) * 100 = 2.04 %

Mole Percent Composition of O (Oxygen):
(4 * 0.1145 mol) / (0.1145 mol + 5.55 mol) * 100 = 7.94 %

So, the mole percent composition of the solute (K2SO4) in the solution is approximately 2.02% K, 2.04% S, and 7.94% O.

I hope this explanation helps you understand how to determine both percent composition by mass and mole percent composition!