A student is asked to make label for a solution of 1M sodium hydroxide. Analyze the chemical label they prepared (shown below) for its completeness:

1M NaOH (in H2O)

Caution: Corrosive

Date: 04/01/2021 Prepared by: Jessie Doe

Question

A student is asked to make label for a solution of 1M sodium hydroxide.  Analyze the chemical label they prepared (shown below) for its completeness:

1M NaOH (in H2O)

Caution: Corrosive

Date: 04/01/2021 Prepared by: Jessie Doe

BlackTom AI · Accepted Answer

First, I’m going to restate the scenario and the answer options so we can evaluate them clearly.
Question: A student is asked to make a label for a solution of 1M sodium hydroxide. Analyze the chemical label they prepared (shown below) for its completeness:

1M NaOH (in H2O)

Caution: Corrosive

Date: 04/01/2021 Prepared by: Jessie Doe

Answer options:
- The label is complete, nothing is missing.
- The label is not complete, hazards are not listed.
- The label is not complete, the full chemical name is not included.
- The label is not complete, CAS # should be listed.
- The label is not complete, the date prepared is not listed.

Now, let’s assess each option one by one.

Option 1: The label is complete, nothing is missing.
- Why this is likely incorrect: Safety labeling standards typically require more information for a chemical solution than what is shown. Even though hazards are noted as Corrosive, more details may be expected (such as specific hazard statements or precautionary statements). Also, common labeling practice often includes a CAS number and sometimes the full chemical name. This option asserts nothing is missing, which conflicts with standard lab labeling practices.

Option 2: The label is not complete, hazards are not listed.
- Why this is questionable: The label does indicate a hazard: Corrosive. That line provides at least a basic hazard note. However, some systems require explicit hazard statements or pictograms, and the word Corrosive alone may be considered a hazard descriptor. Depending on the standard being followed, this could be seen as insufficient, but the option claims hazards are not listed at all, which is not true since a corrosion warning is present. Therefore this option exaggerates the deficiency.

Option 3: The label is not complete, the full chemical name is not included.
- Why this might be considered: Sodium hydroxide is commonly written as NaOH; the full chemical name could be stated as sodium hydroxide vs. NaOH, depending on labeling rules. Some labeling standards prefer the full chemical name in addition to the formula. However, in many contexts, the chemical name is acceptable and the formula is standard; this alone may not render the label incomplete unless a specific naming requirement is in place.

Option 4: The label is not complete, CAS # should be listed.
- Why this is a strong candidate: The CAS (Chemical Abstracts Service) number uniquely identifies sodium hydroxide (the CAS is 1310-73-2 for NaOH). Including the CAS number is a common requirement for chemical labels in many safety guidelines and helps with unambiguous identification, especially in mixtures or solutions. The provided label lacks the CAS number, which is a plausible missing element.

Option 5: The label is not complete, the date prepared is not listed.
- Why this is unlikely to be the primary deficiency: The label does include a Date: 04/01/2021, which indicates when it was prepared. Therefore, claiming that the date prepared is missing is factually incorrect based on the information shown. This option misstates the content of the label.

Bringing it together, we evaluate what is most plausibly considered the missing element according to standard chemical labeling practices. While there is a date and a hazard descriptor, the absence of a CAS number is a common and specific missing identifier that many safety protocols require. The other items (full name vs. formula, hazard statements, or completeness of hazards in general) may vary by standard, but CAS number is a concrete, widely mandated piece of information.

Putting it concisely: The label’s missing CAS number is the concrete deficiency that aligns with common labeling requirements, whereas the date is present, the hazard is at least noted as corrosive, and the naming issue is less uniformly mandated. Therefore, option 4 identifies a definite missing item that is typically required for completeness, while option 5 misreads the date, and option 2 incorrectly suggests hazards aren’t listed at all. The question’s given correct answer matches the emphasis on CAS #.

CHEM100A_SP25_LST CHEM 100A: LAB SAFETY EXAM - Spring 2025

A student is asked to make label for a solution of 1M sodium hydroxide. Analyze the chemical label they prepared (shown below) for its completeness: 1M NaOH (in H2O) Caution: Corrosive Date: 04/01/2021 Prepared by: Jessie Doe

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