An unsaturated solution is made by completely dissolving 20.0 grams of NaNO3 in 100.0 grams of water at 20.0°C. (the gram formula mass=85.0 grams per mole)

Determine the minimum mass of NaNO3 that must be added to this unsaturated solution to make a saturated solution at 20.0°C.

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To determine the minimum mass of NaNO3 needed to make the unsaturated solution saturated, we need to consider the solubility of NaNO3 at 20.0°C. The solubility of NaNO3 refers to the maximum amount of NaNO3 that can dissolve in a given amount of solvent at a specific temperature.

From the information provided, the solution at hand is unsaturated, which means it can still dissolve more solute. So, to make it saturated, we need to add an additional amount of NaNO3 until no more can dissolve.

Here's how you can find the minimum mass of NaNO3 needed to saturate the solution:

1. Look up the solubility of NaNO3 at 20.0°C.
- The solubility of NaNO3 is typically given in units like grams per 100 grams of water, grams per liter of water, or moles per liter of water. Make sure the units match the information given in the question.

2. Calculate the amount of NaNO3 already in the unsaturated solution.
- The question states that 20.0 grams of NaNO3 were dissolved in 100.0 grams of water. Convert the grams of NaNO3 to moles using the molar mass (gram formula mass) of NaNO3.

3. Determine the amount of additional NaNO3 needed to reach saturation.
- Subtract the amount of NaNO3 already in the solution from the solubility value obtained in step 1. This will give you the amount of NaNO3 needed to reach saturation.

Remember to convert between grams and moles as necessary using the molar mass of NaNO3 (85.0 grams per mole).

Calculating the molar mass of NaNO3:
Na: 22.99 g/mol
N: 14.01 g/mol
O: 16.00 g/mol
3O: 3 × 16.00 g/mol = 48.00 g/mol
Total: 22.99 g/mol + 14.01 g/mol + 48.00 g/mol = 84.00 g/mol

Once you have the solubility value and the amount of NaNO3 already in the solution, you can perform the calculations to find the minimum mass of NaNO3 needed to make the solution saturated.

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