Final answer:
Acid and ice are added to the triphenylmethanol ion in the fume hood to neutralize the solution, drive the reaction, and manage the release of heat and toxic fumes safely.
Step-by-step explanation:
It is important to add acid and ice to the intermediate (triphenylmethanol ion) in a fume hood because acids can release toxic gases and the reaction can also generate heat. The addition of acid to the reaction serves to neutralize the solution to meet environmental standards and to drive the reaction forward by increasing the concentration of H3O+ ions, which in turn catalyzes the formation of the triphenylmethanol ion. The presence of toxic fumes necessitates the use of a fume hood for safety, and ice is often used to control the reaction temperature, preventing overheating that could lead to dangerous conditions or decomposition of the desired product.
When concentrated sulfuric acid is used, it is important to add it to water rather than vice versa, as this can release a significant heat of solution, and adding water to acid can cause dangerous splattering. Moreover, acidic solutions can corrode metals and impact the stress corrosion process. Hence, the fume hood provides a controlled environment to manage these potential hazards safely.