You and you're lab partner are making the 5.0% salt solution needed in this experiment. Why will this procedure not work?

Question

Your lab partner, who is fond of cutting corners, suggests that you can calculate the density quicker than the procedure in the lab. He/She places a beaker on the scale and tares it. Now he/she adds salt until the scale reads 1.58g. Next, without taring the scale, a volumetric pipet is used to add 30.00 mL of water. Your partner says the density of the solution is simply the total mass the scale now says, divided by volume, which is 30.00 mL.

Answer 1

The proposed solution of the lab partner assumes that the final volume of solution is 30.00 mls. This will not be the case because the mass of the salt will contribute to the final volume. If calculating the density, one must consider the final volume of solution, not the volume of solvent added.