When dissolving a solid or a liquid, remember to add the chemical to water, rather than vice versa, especially when diluting concentrated acids.
When the solute is a solid, first dissolve the solid in a vessel other than the volumetric flask (a beaker or Erlenmeyer flask). Occasionally, a solid will not dissolve readily and the mixture must be heated to aid dissolution.
NEVER heat a solution in a volumetric flask.
After the solid dissolves, pour the solution into the volumetric flask and use the solvent to rinse all of the solution from the vessel into the flask (a "quantitative transfer"). However, if the solid is known to be very soluble, it may be added directly to the flask.
The student in the video believes that he prepared a 0.5236 M NaCl solution. Is the actual molarity higher or lower than 0.5236 M? Why?
Answer
The actual molarity of the NaCl solution is lower than 0.5236 M. The student first attempted to dissolve the NaCl in a separate vessel, which is the correct procedure; however, he did not dissolve all of the NaCl, so the entire quantity of solute was not transferred to the volumetric flask. Since the number of moles transferred was less than anticipated, the actual molarity of the solution is lower than expected.
The student in the video believes that he prepared a 0.5236 M NaCl solution. Is the actual molarity higher or lower than 0.5236 M? Why?