Answer :
Molarity is a measure of the concentration of a solute in a solution. It is defined as the number of moles of solute dissolved per liter of solution and is represented by the symbol "M". the colleague would need approximately 0.558 liters (or 558 milliliters) of the 3.0 M stock solution of NaCl to obtain 97.9 grams of NaCl.
To calculate the volume of the stock solution needed, we can use the relationship between moles, concentration, and volume. First, we need to determine the number of moles of NaCl in 97.9 grams.
[tex]\[\text{{Number of moles}} = \frac{{\text{{Mass}}}}{{\text{{Molar mass}}}} = \frac{{97.9 \, \text{{g}}}}{{58.44 \, \text{{g/mol}}}} \approx 1.675 \, \text{{mol}}\][/tex]
The equation for molarity is:
[tex]\[ \text{Molarity} = \frac{\text{Moles}}{\text{Volume}} \][/tex]
[tex]\[ \text{Volume} = \frac{\text{Moles}}{\text{Molarity}} = \frac{1.675 \, \text{mol}}{3.0 \, \text{mol/L}} \approx 0.558 \, \text{L} \][/tex]
Therefore, the colleague would need approximately 0.558 liters (or 558 milliliters) of the 3.0 M stock solution of NaCl to obtain 97.9 grams of NaCl.
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