Final answer:
It is generally false that a NaOH solution does not need re-standardization if used from a previous week, as NaOH can absorb CO2 from air, altering concentration. Verification of stability is essential, and precise experimental methods must be followed for accurate titration calculations.
Step-by-step explanation:
The statement that for an experiment, you will use the NaOH solution from last week's experiment 8, and thus will not need to re-standardize this base solution, depends on the stability of the NaOH solution over time. Generally, the answer would be false because NaOH solutions can absorb carbon dioxide from the air, which can affect the concentration as it forms sodium bicarbonate.
However, if the NaOH solution were properly stored to prevent CO2 absorption and the concentration is confirmed to be stable, then it might not require re-standardization. Laboratory protocol usually requires re-standardization of solutions after a certain period to ensure accuracy.
For example, if 25.00 mL of HCl solution with a concentration of 0.1234 M is neutralized by 23.45 mL of NaOH, calculating the molarity of the NaOH solution can be done using the stoichiometry of the neutralization reaction. This calculation is essential for accurate titrations.
Precise mass measurement and correct dissolution practices are crucial to achieve an accurate concentration of NaOH in solution.