To calculate the concentration of Na2S2O3 in the reaction solutions, you need to determine the amount of Na2S2O3 in moles and divide it by the total volume of the reaction solution.
Step 1: Convert the volume of Na2S2O3 used in each flask to moles.
Since each flask contains 2.50 mL of Na2S2O3, and there are 6 flasks, the total volume of Na2S2O3 used is 2.50 mL/flask x 6 flasks = 15 mL.
Step 2: Convert the volume of Na2S2O3 to moles.
To do this, you need to know the molar concentration (also known as molarity) of Na2S2O3, expressed in moles per liter (mol/L).
Let's assume the molar concentration of Na2S2O3 in your experiment was 0.1 mol/L.
Therefore, the amount of Na2S2O3 in moles can be calculated using the formula:
moles = concentration (mol/L) x volume (L)
moles = 0.1 mol/L x 0.015 L (since 15 mL is equal to 0.015 L)
moles = 0.0015 mol of Na2S2O3
Step 3: Calculate the concentration of Na2S2O3 in the reaction solutions.
To determine the concentration, divide the moles of Na2S2O3 by the total volume of the reaction solution.
Let's assume the total volume of the reaction solution is 250 mL (0.250 L).
concentration = moles/volume
concentration = 0.0015 mol/0.250 L
concentration = 0.006 mol/L or 6 mmol/L (millimoles per liter)
Therefore, the concentration of Na2S2O3 in the reaction solutions is 6 mmol/L.