Solubility curves
A solubility curve is a graph of solubility, measured in g/100 g water, against temperature in °C. Solubility curves for more than one substance are often drawn on the same graph, allowing comparisons between substances.
Question
Use the graph above to calculate the mass of sodium nitrate, NaNO3, solid that forms when a A solution in which the maximum mass of a solid is dissolved at a particular temperature. of sodium nitrate, containing 50 g of water, is cooled from 50°C to 10°C.
From the graph, 50°C the solubility of NaNO3 is 115 g/100 g of water. At 10°C it is 80 g/100 g of water.
At 50°C, the mass of NaNO3 that will saturate 50 g of water is:
\( \frac {80}{2} = 57.5 g~per~50 g~water \)
At 10°C, the mass of NaNO3 that will saturate 10 g of water is:
\( \frac {115}{2} = 40 g~per~50 g~water \)
Mass of solid which deposits is 57.5 - 40 = 17.5 g