Answer:
Question is incomplete i have added full question at the end of this answer because im not able to add it in ask for detail section.
Answer:
1. Contaminate (Because NaOH is a base while H2SO4 is an acid. If student mix both this will result in chemical reaction.)
2. Contaminate (Because returning regents are used already id used regents put back in the bottle it will contaminate the fresh reagents.)
3. Contaminate (Using same spatula without sanitation results in mixing of one reagent into other regents which results in failure of experiments.)
4. Does Not Contaminate (It does not have any effect on the reagent because solid reagents are weighted that can be cleaned off when poured into reaction flask.)
5. Does Not Contaminate (Because washing flask after each experiment will wash off the left reagents present in flask.)
6. Contaminate (This will result in contamination because potassium iodide (KI) solution will be mixed with waste)
FULL QUESTION
Maintaining the integrity of the stock reagents is a constant concern in the lab environment. Read the following situations and decide if each represents a valid contamination concern.
1. A student uses a pipet designated for the NaOH solution to pipet the H2SO4 solution.
2. Several students have left-over reagents after the completion of an experiment and decide to return the excess reagents to their original containers.
3. Only one spatula is available to measure out several different white powders.
4.Rather than wasting multiple weigh boats, a student decides to wash and dry a single weigh boat in-between uses.
5. A group of students must use the same 500 mL volumetric flask to make solutions. Between each use they wash and dry the flask.
6. At the end of the day, the waste bottle is so full that a student decides to dump his waste into an almost empty bottle of stock KI solution.
