What is an example practice problem involving a solvent?

Question

Noah Aldrich · Accepted Answer

Why can the solute(s) that are miscible or soluble in the solvent of choice be circled or selected? NONPOLAR
1. Solvent: #"C"_6"H"_14# (n-hexane)
Solutes: #"C"_3"H"_8# (n-propane), #"NaCl"# (sodium chloride), #"CH"_3"CH"_2"OH"# (ethanol) POLAR PROTIC
2. Solvent: #"H"_2"O"# (water)
Solutes: #"C"_4"H"_10# (n-butane), #"LiI"# (lithium iodide), #"CH"_3"CH"_2"OH"# (ethanol) POLAR APROTIC
3. Solvent: #"H"_3"C"("C"="O")"CH"_3# (acetone)
Solutes: #"C"_5"H"_12# (n-pentane), #"H"_2"O"# (water), #"CH"_3"CH"_2"OH"# (ethanol)

Kai Bowman · Answer

undefined An example practice problem involving a solvent could be:

Calculate the mass of solvent needed to prepare a 500 mL solution of 0.25 M sodium chloride (NaCl). The density of the solvent is 1.00 g/mL.

Solution:
1. Determine the number of moles of NaCl needed:
   $ \text{Molarity (M)} = \frac{\text{moles of solute}}{\text{volume of solution (L)}} $
   $ 0.25 \, \text{M} = \frac{\text{moles of NaCl}}{0.500 \, \text{L}} $
   $ \text{moles of NaCl} = 0.25 \, \text{M} \times 0.500 \, \text{L} = 0.125 \, \text{moles} $

2. Calculate the mass of NaCl needed:
   $ \text{mass of NaCl} = \text{moles of NaCl} \times \text{molar mass of NaCl} $
   $ \text{mass of NaCl} = 0.125 \, \text{moles} \times 58.44 \, \text{g/mol} = 7.305 \, \text{g} $

3. Determine the mass of the solvent:
   $ \text{mass of solvent} = \text{volume of solution} \times \text{density of solvent} $
   $ \text{mass of solvent} = 500 \, \text{mL} \times 1.00 \, \text{g/mL} = 500 \, \text{g} $

Therefore, the mass of solvent needed to prepare the solution is 500 grams.