1)20 mL of a saturated of potassium nitrae at 50oC. Approximately, what mass of solid will precipiatae from the solution?

2)At 80oC, what mass of sodium dissolves in 1.0L of water

3.What minimum temperature is required to dissolve 24 g of potassium nitrate in 40 g of water? is cooled to 20oC.

okay, thank you, but i don't understand number two

I don't either. Unless the idea is that Na will react with H2O to form NaOH and you have a table or graph that tells you the solubility of NaOH. If you have that I can help further.

At 80oC, what mass of sodium chloride dissolves in 1.0L of water

sorry, i made a mistake

To answer these questions, we need to use the concept of solubility. Solubility is the maximum amount of solute that can dissolve in a given amount of solvent at a specific temperature.

1) To determine the mass of solid that will precipitate from the solution, we need to find the solubility of potassium nitrate at 50°C. We can use a solubility table or reference to find this information. Let's assume that the solubility of potassium nitrate at 50°C is 150 g/L.

Since we have 20 mL (which is equal to 0.02 L) of the solution, we can calculate the mass of solid that will precipitate using the solubility:

Mass of solid = Solubility × Volume of solution
Mass of solid = 150 g/L × 0.02 L
Mass of solid = 3 grams

Therefore, approximately 3 grams of solid will precipitate from the solution.

2) To determine the mass of sodium that dissolves in 1.0L of water at 80°C, we need to find the solubility of sodium at that temperature. Let's assume that the solubility of sodium at 80°C is 50 g/L.

Using the solubility, we can calculate the mass of sodium that dissolves:

Mass of sodium = Solubility × Volume of water
Mass of sodium = 50 g/L × 1.0 L
Mass of sodium = 50 grams

Therefore, approximately 50 grams of sodium will dissolve in 1.0L of water at 80°C.

3) To find the minimum temperature required to dissolve 24 g of potassium nitrate in 40 g of water, we need to know the solubility of potassium nitrate in water. Assume that the solubility of potassium nitrate at 20°C is 30 g/100 g of water.

Using the solubility, we can calculate the mass of potassium nitrate that can dissolve in 40 g of water:

Maximum mass of potassium nitrate = Solubility × Mass of water
Maximum mass of potassium nitrate = 30 g/100 g × 40 g
Maximum mass of potassium nitrate = 12 grams

Since we have 24 g of potassium nitrate, which is higher than the maximum mass that can dissolve, we need to increase the temperature. We need to find the minimum temperature at which 24 g can dissolve in 40 g of water.

Using the concept of solubility, we can set up a proportional relationship using the mass of solute and the temperature:

[mass1 / mass2] = [solubility1 / solubility2]

(24 g / 40 g) = (solubility at 20°C / solubility at the minimum temperature)

Solving for the minimum temperature:

(solubility at 20°C / 30 g/100 g) = (24 g / 40 g)
solubility at 20°C = 30 g/100 g
24 g = (40 g / 100 g) × solubility at the minimum temperature
(40 g / 100 g) = 24 g / solubility at the minimum temperature
solubility at the minimum temperature = (24 g × 100 g) / 40 g
solubility at the minimum temperature = 60 g/100 g
solubility at the minimum temperature = 0.6 g/1 g

So, the minimum temperature required to dissolve 24 g of potassium nitrate in 40 g of water is 0.6°C.

Surely you have a table or a graph in your text or notes. I don't have solubilities of every salt memorized.