190 grams of potassium iodide is placed in 100 cm3 at 60 degrees Celsius. the solution is cooled to 30 degrees Celsius. how many grams will settle out?
Find the Ksp of KI at 30C.
Ksp = [K{+}]*[I{-}]
That will determine the mole concentration of dissolved KI. Multiply by volume (in L) and molecular mass to determine the mass. Subtract that from the mass of supersaturated KI to determine the mass of precipitate.
We need the solubility of KI at 60 C and at 30 C in order to help you. I expect you have that info either in the problem or in a table. Supply that info for us to help.
To calculate how many grams of potassium iodide will settle out when the solution is cooled, we need to determine its solubility at different temperatures. Solubility is the maximum amount of a substance that can dissolve in a particular solvent at a given temperature.
1. Find the solubility of potassium iodide at 60 degrees Celsius:
You can search for a solubility chart or table that provides the solubility of potassium iodide at different temperatures. For example, let's say the solubility of potassium iodide at 60 degrees Celsius is 150 grams per 100 cm^3 (this value is for illustration purposes only).
2. Calculate the maximum amount of potassium iodide that can dissolve at 60 degrees Celsius:
Since the solution initially contains 100 cm^3 of liquid, and the solubility at 60 degrees Celsius is 150 grams per 100 cm^3, we can set up a proportion to find the amount of potassium iodide that will dissolve in 100 cm^3 of the solution:
- 150 grams of KI / 100 cm^3 of solution = x grams of KI / 100 cm^3 of solution
By cross-multiplying, we get:
- 150x = 100 * 190
- x = (100 * 190) / 150
- x = 126.67 grams
Therefore, at 60 degrees Celsius, 126.67 grams of potassium iodide will dissolve in 100 cm^3 of the solution.
3. Find the solubility of potassium iodide at 30 degrees Celsius:
Following the same process as before, let's say the solubility of potassium iodide at 30 degrees Celsius is 100 grams per 100 cm^3 (again, this value is for illustration purposes only).
4. Calculate the maximum amount of potassium iodide that can dissolve at 30 degrees Celsius:
With the same initial volume of 100 cm^3 of liquid, and the solubility at 30 degrees Celsius of 100 grams per 100 cm^3, we use the proportion:
- 100 grams of KI / 100 cm^3 of solution = x grams of KI / 100 cm^3 of solution
Solving for x, we find:
- 100x = 100 * 190
- x = (100 * 190) / 100
- x = 190 grams
At 30 degrees Celsius, 190 grams of potassium iodide will dissolve in 100 cm^3 of the solution.
5. Calculate the grams of potassium iodide that will settle out when the solution is cooled:
The amount that settles out is the difference between what dissolved at 60 degrees Celsius and what can remain dissolved at 30 degrees Celsius.
- Grams that will settle out = Grams dissolved at 60°C - Grams that will dissolve at 30°C
- Grams that will settle out = 126.67 grams - 190 grams
- Grams that will settle out = -63.33 grams
Since the result is negative, it means that all the potassium iodide will remain dissolved in the solution even after cooling. No potassium iodide will settle out.
Please note that the solubility values used in this explanation are for illustration purposes and may not accurately reflect the actual values for potassium iodide at the given temperatures.