How to prepare a 750mL stock solution with a 0.40 M Na2S2O3.
What concn do you want the stock solution?
mols you want = M x L = ?
Then 0.40M x mL = 750 x concn.
Note: The above is the correct solution to the problem posted; however, I suspect what you meant was how to prepare 750 mL of a stock solution OF (not with) 0.40M Na2S2O3.
Yes, I should have typed of, how would I go into more detail of the procedure to make this stock solution? In other words, calculating the of each chemical needed, how much sodium and thiosulfate would need to be added. Thanks again, DrBob222.
You want to prepare 750 mL of a 0.4M Na2S2O3 solution.
You want how many mols? That's M x L = 0.40 M x 0.750 L = 0.30 mols.
mols Na2S2O3 = grams Na2S2O3/molar mass
g = mols x molar mass = 0.3 x molar mass Na2S2O3.
Weigh out that many grams Na2S2O3, place into a 750 mL volumetric flask, add distilled water, swirl until all of the solute is dissolved, make to the mark with distilled water.
To prepare a 750 mL stock solution with a concentration of 0.40 M Na2S2O3, you need to follow a few steps:
Step 1: Determine the amount of Na2S2O3 required. The concentration (0.40 M) is given, which means there are 0.40 moles of Na2S2O3 in 1 liter of solution. We want to prepare a 750 mL (0.75 L) stock solution, so we need to calculate the number of moles of Na2S2O3 needed.
Moles of Na2S2O3 = Concentration (M) × Volume (L)
Moles of Na2S2O3 = 0.40 M × 0.75 L
Moles of Na2S2O3 = 0.30 mol
Step 2: Convert moles to grams. To convert moles of Na2S2O3 to grams, you need to know its molar mass (grams per mole). The molar mass of Na2S2O3 is calculated by adding up the atomic masses of its constituent elements.
Molar mass of Na2S2O3 = (2 × Atomic mass of Na) + Atomic mass of S + (3 × Atomic mass of O)
Using the atomic masses from the periodic table, we can calculate the molar mass:
Molar mass of Na2S2O3 = (2 × 22.99 g/mol) + 32.06 g/mol + (3 × 16.00 g/mol)
Molar mass of Na2S2O3 = 158.11 g/mol
Next, we can calculate the mass of Na2S2O3 needed:
Mass of Na2S2O3 = Moles of Na2S2O3 × Molar mass of Na2S2O3
Mass of Na2S2O3 = 0.30 mol × 158.11 g/mol
Mass of Na2S2O3 = 47.43 g
Step 3: Add Na2S2O3 and solvent. Measure out and add 47.43 grams of Na2S2O3 to a container. Then, add enough solvent, such as water, to make a total volume of 750 mL. Stir the mixture until the Na2S2O3 is completely dissolved.
That's it! You have prepared a 750 mL stock solution with a concentration of 0.40 M Na2S2O3.