Question

a chemistry student is given 650. ml of a clear aqueous solution at 28.°c. he is told an unknown amount of a certain compound x is dissolved in the solution. the student allows the solution to cool to 18.°c. at that point, the student sees that a precipitate has formed. he transfers the liquid to a clean new beaker and throws away the precipitate. the student then evaporates the water from the liquid in the new beaker under vacuum. it weighs 0.13 kg. using only the information above, can you calculate the solubility of x in water at 18.°c? yes no if you said yes, calculate it. be sure your answer has a unit symbol and the right number of significant digits.

Explanation:

Step1: Convert units

Convert the mass of the solute from kilograms to grams: \(0.13\space kg\times1000 = 130\space g\).
Assume the density of water is \(1\space g/mL\), so the mass of water is \(650\space g\) (since \(m=
ho V\) and \(
ho = 1\space g/mL\), \(V = 650\space mL\)).

Step2: Calculate solubility

Solubility is defined as the mass of solute per \(100\space g\) of water.
Let \(S\) be the solubility. Using the formula \(S=\frac{\text{mass of solute}}{\text{mass of water}}\times100\).
Substitute the values: \(S=\frac{130\space g}{650\space g}\times 100\).

Answer:

\(20\space g\) per \(100\space g\) water.