Determine the expected volume of titrant needed to reach the endpoint if Patrick used the stockthiosulfate solution.

To determine the expected volume of titrant needed to reach the endpoint if Patrick used the stockthiosulfate solution, you can follow these steps:

1. Determine the concentration of the stockthiosulfate solution. This information should be provided in the experiment or can be calculated if you know the amount of solute and the volume of the solution.

2. Calculate the number of moles of the analyte (the substance being titrated) that you have in your sample. This can be done by multiplying the concentration of the analyte by the volume of the sample.

3. Determine the stoichiometry of the reaction between the analyte and the titrant. This information should be provided in the experiment or can be found in a chemical equation.

4. Use the stoichiometry to determine the number of moles of titrant needed to react completely with the analyte. This can be done by using the mole ratio between the analyte and the titrant.

5. Finally, divide the number of moles of titrant needed by the concentration of the stockthiosulfate solution to calculate the volume of titrant needed to reach the endpoint.

It is important to note that these steps are general guidelines and may vary depending on the specific experiment or titration being performed.