If 100 grams of a saturated solution of lead nitrate is cooled from 60c to 20c, what will happen
Some of the Pb(NO3)2 will crystallize since the solubility is less at 20C that at 60C.
100g of Pb(NO3)2 dissolve 0.297moles. 1000g of Pb(NO3)2 will dissolve 0.297*1000/100=2.97 mol/dm3
When a saturated solution of lead nitrate is cooled, the solubility of the compound generally decreases. This means that as the temperature decreases, the solution can no longer hold as much dissolved lead nitrate, leading to the formation of precipitates.
To determine what will happen in this specific case, we need to consider the solubility curve of lead nitrate. The solubility curve shows the relationship between temperature and the maximum amount of solute that can dissolve in a given solvent.
First, we need to find the solubility of lead nitrate at both 60°C and 20°C. Let's assume that at 60°C, the solubility is 200 grams per 100 grams of water, and at 20°C, the solubility is 80 grams per 100 grams of water.
Since the given solution is saturated, it means that it already contains the maximum amount of lead nitrate that can dissolve at a given temperature. Therefore, if we cool the solution from 60°C to 20°C, the solubility of lead nitrate decreases from 200 grams to 80 grams per 100 grams of water.
Now, let's compare the amount of lead nitrate in the original solution (100 grams) with the solubility at 20°C (80 grams per 100 grams of water). Since the solubility is lower than the initial concentration, it means that some of the lead nitrate will no longer remain dissolved in the solution as it cools. Precipitation will occur, and solid lead nitrate will form at the bottom of the container.
Note: The exact amount of precipitate formed will depend on the initial concentration of the solution and the specific solubility values. The values used in this explanation are hypothetical and should not be considered precise.