posted by Jennifer on .
An experiment in your laboratory requires 500 mL of a .0200 M solution of Na2CO3. You are given solid Na2CO3, distilled water and a 500 mL volumetric flask Describe how to prepare the required solution showing all calculations and describing each step appropriately.
It is important that you know HOW to prepare a solution.
You want how many moles? That is M x L = 0.02 x 0.500 = ? moles. How many grams is that. grams = moles x molar mass.
That's the easy part. Here is the tricky part. Weigh the grams calculated above exactly, transfer quantitatively to the 500 mL volumetric flask, add a LITTLE water, swirl until ALL of the salt is dissolved, then make to the makr with DI or distilled water. Shake and mix thoroughly. Two important points in my description.
1. You do NOT add the salt to 500 mL H2O because then the solution will be more than (some solutes) or less than(some solutes) when the solute goes into solution.
2. You add the salt to the flask, add some water and swirl until all of the salt is dissolved. See #1 for why.